# How to decide on 15a or 20a breakers???



## timothy300858 (Mar 10, 2014)

All of my receptacles are 15a and all the GFi's are 20a that Im using.... I had the lower level roughed in by a friend who is an electrician....He does have the lighting on separate circuits than the receptacles which im assuming is the same idea I should use for the upper level. That is where I get confused.. How do I decide what size breakers...


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## mpoulton (Jul 23, 2009)

Some circuits are required to be 20A (at least two in the kitchen, and at least one in the bathroom and laundry). All others can be either 15 or 20A. A duplex receptacle (an outlet that you can plug two cords into, like normal) is TWO receptacles, so you can use a single 15A duplex receptacle on a 20A circuit, whether GFCI or not. A 15A GFCI can be used on a 20A circuit - it's rated 15A per outlet, 20A total. There is little or no need for 20A receptacles in a home, because hardly anyone has any appliances that use the special 20A plug (one prong horizontal). Any circuit using #14 wire cannot use a 20A breaker (unless it's a very special circuit which you're not dealing with). Any circuit with #12 wire can use a 20A breaker, or could use a 15A but there's no good reason to do that.


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## timothy300858 (Mar 10, 2014)

Okay, then that leads to my next question.. Im using nothing but 12# wire for everything... Does that mean I need to change all my breakers to 20a???


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## mpoulton (Jul 23, 2009)

timothy300858 said:


> Okay, then that leads to my next question.. Im using nothing but 12# wire for everything... Does that mean I need to change all my breakers to 20a???


People have been over this repeatedly in your other threads. I don't know how to be any clearer without just quoting a bunch of NEC provisions. Wire is sized to the load. Breakers protect wire, so they are sized to the wire - and also the load. Some circuits MUST be 20A, like the required laundry and kitchen circuits. The assumed load is 20A, so the wire is required to be #12 and the breaker is required to be 20A. Other circuits can be 15A or 20A, and if you choose to make them 20A then you must use #12 wire. Otherwise you could use 15A breakers. There is no good reason to use a 15A breaker on #12 wire though, except in unusual circumstances that don't apply here.


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## dgfit (Jun 5, 2013)

The size of the breaker really depends on the size of the wire. The maximum amps #14 wire can safely carry is 15 amps and the maximum that #12 can safely carry is 20 amps. So choose a breaker accordingly.

To be code compliant, you need to install the required circuits (including properly sized wire and breaker, and receptacle) called for by code. For example, you need at least 2 20 GFCI amp circuits used for small appliances with outlets placed at maximum specified distances. You will also install one 20 amp circuit for the laundry room. There are also requirements for the bathroom. In addition, there are requirements for interconnected smoke alarms as well as outdoor outlets. Some circuits require GFCI breakers and some require AFCI breakers. There are requirements for numbers of lighting circuits per square footage. There are many more - suggest you read some of the links you were provided on other threads.

I recommend you adhere to the codes and get the work inspected to help ensure safety, and avoid having your insurance company deny claims due to unpermitted work.


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## timothy300858 (Mar 10, 2014)

I understand what you are saying and I understand others have given answers about the same subject. So if there is no good reason to use 15a breakers on 12# wire, then why didn't you just say .. yes, change all your breakers to 20a seeing that Im using 12# wire only???? Am I missing something here???


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## dgfit (Jun 5, 2013)

You don't want more than 15 amps flowing on a #14 wire, and you don't want more than 20 amps flowing on #12 wire. A 15 amp breaker will prevent 20 amps from flowing on #12 wire.

But that is all a different question as to which you should use. If you want to be code compliant, then you need things like 2 20 amp GFCI circuits for kitchen counters. That would mean those circuits need to have 20 amp breakers, #12 wire, and 20 amp outlets protected by GFCI.


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## beenthere (Oct 11, 2008)

I think people may be missing that you already have 15 amp breakers in your panel. And its not like you don't have any breakers and are just deciding what size to buy.


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## dgfit (Jun 5, 2013)

timothy300858 said:


> I understand what you are saying and I understand others have given answers about the same subject. So if there is no good reason to use 15a breakers on 12# wire, then why didn't you just say .. yes, change all your breakers to 20a seeing that Im using 12# wire only???? Am I missing something here???


There are times when it makes sense to use 15 amp breakers on #12 wire. For example, when the circuit is long enough such that the voltage drops enough over the length of the wire, then you want to use bigger wire, but not necessarily allow more current to flow. There are online calculators to compute this. This is not based on a code requirement, but is considered to be good design. It rarely comes into play in average sized homes.

In addition, the code requires conductors to be derated in certain circumstances. In one example - if the wires are in a hot attic, you have to reduce the maximum amps that flow on the wire. In this instance, you might need to use #12 wire in order to meet the needs of the circuit while still only allowing a max of 15 amps via a 15 amp breaker. This a code requirement to ensure safety.

There are many many considerations such as these that electricians are required to know in order to be licensed. DIYers can do it too - like me - but I have learned the value of listening to what is said here and do a LOT of studying.


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## timothy300858 (Mar 10, 2014)

I have a 20 breaker panel and all the spots are full.. Right now I have 3 breakers that aren't in use along with 4 breakers that the upstairs are wired up with... So I will technically have 7 breakers that will be for the upstairs level ... If I have to have an additional smaller breaker box added for more, that is def a possibility. One of the issues I have with all this is people keep bringing up 14# wire.. Im NOT using anything but 12# romex wire... I could care less about any info for 14#, Im sorry.... All I wanna make sure is that Im using the correct size breaker for certain things... I understand for the kitchen, bathrooms and laundry, I need 20a breakers....


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## dgfit (Jun 5, 2013)

timothy300858 said:


> I have a 20 breaker panel and all the spots are full.. Right now I have 3 breakers that aren't in use along with 4 breakers that the upstairs are wired up with... So I will technically have 7 breakers that will be for the upstairs level ... If I have to have an additional smaller breaker box added for more, that is def a possibility. One of the issues I have with all this is people keep bringing up 14# wire.. Im NOT using anything but 12# romex wire... I could care less about any info for 14#, Im sorry.... All I wanna make sure is that Im using the correct size breaker for certain things... I understand for the kitchen, bathrooms and laundry, I need 20a breakers....


Use 20 amp breakers with your #12 wire and 20 amp receptacles for those circuits required by code to be 20 amp circuits. 
For circuits with #12 wire that are not required to be 20 amp circuits, then you can use either 15 amp breakers or 20 amp breakers. 
Use AFCI breakers wherever they are required.


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## timothy300858 (Mar 10, 2014)

If that was an honest to god response and there is no bull**** behind it, I can honestly say thank you... That is basically all I have been looking for... I was under the impression there is a disadvantage to using 15a breakers... I think I have enough info from the links that have been posted here to know what needs 20a circuits...


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## dgfit (Jun 5, 2013)

timothy300858 said:


> If that was an honest to god response and there is no bull**** behind it, I can honestly say thank you... That is basically all I have been looking for... I was under the impression there is a disadvantage to using 15a breakers... I think I have enough info from the links that have been posted here to know what needs 20a circuits...


I have no interest in bull****ting you. I am interested in your safety and want to share what I have learned.

There is a disadvantage to using 15 amp breakers on #12 wire but it's not related to safety or code requirements. It's simply that if you are using #12 wire, you can put more outlets on a circuit that has a 20 amp breaker than if it has 15 amp breakers. But that may not matter now if the wire is already run and the breakers are already installed.


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## timothy300858 (Mar 10, 2014)

Well I appreciate that very much. Im still learning as I go along. I totally understand what you mean now about the difference between the two size breakers. As far as I can tell, there isn't an abnormal amount of receptacles that are on a certain circuit so would it help if I actually counted how many per circuit and if its minimal, I can change the breaker down to a 15a if its not already??? I cant do anything about the wiring downstairs except change out breakers.. But the upper level I haven't even gotten that far yet so that is something I can control.. Make sense??


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## Jim Port (Sep 21, 2007)

The disadvantage to using a 15 amp breaker with the #12 is that you are wasting 1/3 of the capacity of the wiring that is already installed. This has been repeated several times in multiple threads. The answer is not going to change.

If your friend really is an electrician they should be telling you the same thing.


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## timothy300858 (Mar 10, 2014)

Im going to leave that one alone... I think I am on the right path now so thank you...


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## Jim Port (Sep 21, 2007)

I think we heard the same thing in one of your other threads.


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## dgfit (Jun 5, 2013)

timothy300858 said:


> Well I appreciate that very much. Im still learning as I go along. I totally understand what you mean now about the difference between the two size breakers. As far as I can tell, there isn't an abnormal amount of receptacles that are on a certain circuit so would it help if I actually counted how many per circuit and if its minimal, I can change the breaker down to a 15a if its not already??? I cant do anything about the wiring downstairs except change out breakers.. But the upper level I haven't even gotten that far yet so that is something I can control.. Make sense??


It's not about the number of outlets - you can replace a 20 amp breaker with a 15 amp breaker if the total wattage of the devices plugged into the outlets is 1440 or less. Personally, I would not do this for all the reasons already stated. I would always use 20 amp breakers on #12 wire for all the reasons stated.


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## ddawg16 (Aug 15, 2011)

If you wanted.....you could use 10 AWG with a 10 Breaker....

Ok.....sarcasm aside....

I had one residential sparky tell me that he only uses 12 AWG wire....the cost savings to him is not worth keeping 12 and 14 on his truck.


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## dgfit (Jun 5, 2013)

Fwiw, I am using #12 for all plugs and #14 for all lighting. It is a LOT easier to run #14 through walls and ceilings and there just is no need for #12 in lighting at least in my house. Especially given incandescent bulbs are on the way out.


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## timothy300858 (Mar 10, 2014)

I tried sending a private message to you dgfit... did it go through???


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## dgfit (Jun 5, 2013)

Yes, I just now saw it. Please don't be offended but I would prefer to post my thoughts in the open so that others can correct me if I say something wrong. I'm not a pro - I am a DIYer like you. With my projects so far, I have gained knowledge of the trades and a bit of experience and know that electrical is unique in that it can be made to work for a while, yet still be very unsafe and can later kill. I want to share what I have learned yet want to benefit from what others have to say. It's what makes it a forum 

I know some of these guys are "gruff" and I have my own share of frustrations in that regard. But I have learned the pros know what they are doing and that there are ways of asking questions in order to get the best answers. I really have only said the same things to you that others have said multiple times here but just in a different way. You want to be told very specifically what should be done, but that is rarely easy to do. There are really still many unanswered aspects in the answers I have given - such as where did the 1440 number come from and what are all of the circuits required by the code. I can't emphasize enough that you should read a couple of good books and study the code.

Regarding usage of #12 vs #14 - it's not clear to me if you already have the wire in place or not. If you already have #12 in place then just leave it and use 20 amp breakers. If you don't already have it in place, then my recommendation is to use #12 for outlets with 20 amp breakers and #14 for lighting with 15 amp breakers. But some of this is based on my personal opinions. For example, I have an upstairs and downstairs hall in the middle of my home. I want all the hall lights to be on its own circuit so that if the breaker trips the. I have light from adjoining rooms and vice versa. I am also running through plaster and lath in this 88 year old house and find 14 wire to be much easier to fish. I am running a crapload of 14/3 for 3 and 4 way switches and interconnected smoke alarms.

Regarding can lights - I have no knowledge or experience, but have come to understand that there are safety considerations related to heat. I think someone started to comment in one of these threads.


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## timothy300858 (Mar 10, 2014)

To answer your question, all of the wiring in the lower level in my house is installed and cannot be redone unless I wanna rip all the drywall down that I just put up... As far as the upstairs goes, the old wiring is still installed so when I get to the point of ripping all that out and re-wiring, I will use 14# with 15a breakers and 12# with 20a breakers like what is stated above... As far as using can lights, I will do research and see what comes about ... When it comes to the wiring that is already installed in the lower level, I guess I will change all the breakers to 20a because its all ran with 12# wire.... Atleast that is what Im taking from what you said...


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## dgfit (Jun 5, 2013)

That makes sense to me - one suggestion is search the threads here and also on ElectricianTalk for can lights - I'm sure you will find lots of hits.

So is this the home you expect to live in for a while or expect to sell in a few years? I know I have mentioned a couple of times - but think about what happens if you - or your descendants - go to sell the house and the prospective buyers see it has been rewired and research the permit. It could greatly reduce the value of your home and, legally, the inspector could require you to rip it all out.


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## timothy300858 (Mar 10, 2014)

I understand where you are coming from but Ive never said that I DIDNT have a permit.... And my original plan was to flip the house in 5 years after I purchased it but the way its going, everything will be brand new so I might just wait a bit... It all depends on what the market is like at the time...


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## Rochsolid (Aug 29, 2012)

You can run 12/2 for all your receptacle circuits in your home and use 15 amp breakers, but what the other guys have stated is that, you MUST have 20 amp circuits for kitchen receptacles etc. and this is just my opinion, you gain nothing by using 12/2. If it were my house I'd use 14/2, however with that said, what you have done (by using) 12/2 is perfectly acceptable


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## Syberia (Jan 24, 2014)

I would use 12/2 and 20 amp breakers for all receptacles other than lighting. The cost is minimal (less than $15 for a 250-foot spool of wire last time I checked) and it's never a bad thing to have the extra capacity.


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## sirsparksalot (Oct 16, 2010)

Syberia said:


> I would use 12/2 and 20 amp breakers for all receptacles other than lighting. The cost is minimal (less than $15 for a 250-foot spool of wire last time I checked) and it's never a bad thing to have the extra capacity.


You ain't checked in a while, have you?


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## timothy300858 (Mar 10, 2014)

haha I was thinking the same thing but didn't wanna say it


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## jbfan (Jul 1, 2004)

Syberia said:


> I would use 12/2 and 20 amp breakers for all receptacles other than lighting. The cost is minimal (less than $15 for a 250-foot spool of wire last time I checked) and it's never a bad thing to have the extra capacity.


Do you mean $15 difference between the roll of 14 and the roll of 12?

I haven't checked 14 in a while, but that seems short.


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## Syberia (Jan 24, 2014)

Ok, $22 difference according to homedepot.com. Either way, a small amount of money to avoid potential headaches with tripped breakers.


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## timothy300858 (Mar 10, 2014)

Well I went ahead and made all the breakers for the 12# 20a... And when it comes time to wire the upstairs, I decided to use 12# and 14#


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## dgfit (Jun 5, 2013)

(With 15 amp breakers on the #14 wire)


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## timothy300858 (Mar 10, 2014)

Yes sir!!!!


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## dgfit (Jun 5, 2013)

Have you thought about the interconnected smoke alarms?


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## timothy300858 (Mar 10, 2014)

Actually no... I only have one battery powered one just outside the bedrooms/bathroom upstairs and two of the same kind in the lower level ... I don't think Im gonna be interested in doing that.. But I don't know enough about it to be for sure... I did have one quick question... I noticed the original wiring that hasn't been replaced yet feeding the upstairs is 14/2 .. Should I change all those breakers to 15a??? If you can believe it, there is only 4 that feed the whole upstairs lol


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## dgfit (Jun 5, 2013)

timothy300858 said:


> Actually no... I only have one battery powered one just outside the bedrooms/bathroom upstairs and two of the same kind in the lower level ... I don't think Im gonna be interested in doing that.. But I don't know enough about it to be for sure... I did have one quick question... I noticed the original wiring that hasn't been replaced yet feeding the upstairs is 14/2 .. Should I change all those breakers to 15a??? If you can believe it, there is only 4 that feed the whole upstairs lol


Ok - I only mentioned because code requires the interconnected smokes.

Very important to have 15 amp breakers on #14 wire. That is a safety issue. A 20 amp breaker would allow more current to flow than #14 wire can safely handle.

I'm sure some of the pros would say 4 upstairs circuits is plenty depending on a few factors. If there are bathrooms then there are code required dedicated circuits. Personally, I designed my setup with the idea that my kids / grand kids could have a couple of hair dryers going at the same time


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## timothy300858 (Mar 10, 2014)

Well the way I see it, between the 1 for the bathroom and the 2 dedicated circuits to the kitchen, that only leaves 1 line for the rest ... Im no pro, but I don't think that will cut it. As far as the smoke detectors, Ive never seen any that weren't battery powered. But if they have to be wired in, I will look into it.


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## dgfit (Jun 5, 2013)

Yeah there are hard wired, interconnected smoke alarm requirements (still have battery backup) - one in each sleeping area, one outside sleeping area, one in each living area - basically just about everywhere except kitchens, bathrooms, furnace areas. The idea is if it's somewhere that generates false alarms then you are likely to disable it and therefore not safe. The interconnected are pretty cool really - all alarms sound if any alarm goes off. In my case - if a fire starts in the basement, the alarm in my bedroom will sound.

Some areas require the smoke alarms to be on dedicate circuits and some require them to be on a lighting circuit. The idea there is that if the breaker trips you will know it if lights are off.

You run 14/3 to connect the alarms - the third conductor carries the communication signal.


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## timothy300858 (Mar 10, 2014)

Well that's def something to look into... Its all news to me... But being more safe isn't a bad idea... Real quick.. If I run two circuits to the kitchen for the counter receps which I think with my counter space, I will have four.. I know I can run all four on those two.. But can I use one of them to also wire the fridge or does that need to be on its own? And can I use the other to wire a recep for the stove??? Meaning 2 20a circuits to the kitchen for 4 receps on counter and 2 in the walls??


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## timothy300858 (Mar 10, 2014)

I think I actually found my answer by searching here lol... I can run the fridge and stove off those two 20a circuits just for the kitchen or I can run a 15a circuit to each appliance which would make 4 circuits total to the kitchen... Correct????


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## Jim Port (Sep 21, 2007)

Interconnected smokes have been required for over 20 years.


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## dgfit (Jun 5, 2013)

Need the pros to check me on this, but I believe you can put the fridge on one of the two circuits mentioned (called SABC circuits - Small Appliance Branch Circuits). But you cannot put the stove / range hood on either of those circuits. If you do decide not to put the fridge on one of the SABC, then it must be on a dedicated circuit.

Regarding number of receptacles on the SABC - there are spacing requirements which determine the number of receptacles. I think it's one every three feet, and one is required anywhere there is at least 12 inches of counter space. I am interleaving mine so that every other outlet is on a separate circuit.

I think the dishwasher / disposal are required to be separate but I'm not 100% certain.

I'm sure this is over designed, but I am doing 8 20 amp circuits:

2 SABC circuits
1 disposal
1 dishwasher
1 fridge
1 microwave
1 stove / range hood 
1 for non-SABC wall receptacles shared with dining room


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## dgfit (Jun 5, 2013)

timothy300858 said:


> I think I actually found my answer by searching here lol... I can run the fridge and stove off those two 20a circuits just for the kitchen or I can run a 15a circuit to each appliance which would make 4 circuits total to the kitchen... Correct????


I knew the fridge could, but wasn't sure about the stove. Of course this assuming its a gas stove only.


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## timothy300858 (Mar 10, 2014)

Well.. I can atleast say Im understanding more than I was yesterday... But seeing that I will have a total of 7 breakers to use for the upper level, it sounds like Im going to have to get a smaller box added to the one I have which is ok... I currently don't have a dishwasher or a garbage disposal and Im pretty sure I wont be adding a disposal. As far as the dishwasher goes, that isn't something I had planned on but I def could change my mind. To me it just sounds like a better idea to add a smaller box for more room.. Then I wont have to worry about whats hooked up with what ya know... I might be slow at this but Im willing to learn lol


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## timothy300858 (Mar 10, 2014)

I just wanna do it the correct and safer way... I will be able to do it either way I suppose...


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## Jim Port (Sep 21, 2007)

A gas stove can be on the SABC as can the refrigerator.

Countertop receptacles can be no more than 4' apart.


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## dgfit (Jun 5, 2013)

timothy300858 said:


> Well.. I can atleast say Im understanding more than I was yesterday... But seeing that I will have a total of 7 breakers to use for the upper level, it sounds like Im going to have to get a smaller box added to the one I have which is ok... I currently don't have a dishwasher or a garbage disposal and Im pretty sure I wont be adding a disposal. As far as the dishwasher goes, that isn't something I had planned on but I def could change my mind. To me it just sounds like a better idea to add a smaller box for more room.. Then I wont have to worry about whats hooked up with what ya know... I might be slow at this but Im willing to learn lol


That was my experience as well - once you start digging into it you find there are many many things to consider. There are a couple of black and decker books that are pretty good.

Very good to think about future needs. If you add another box it will be a subpanel. Certainly doable by a DIYer but getting into some much bigger safety issues. Lots of posts here about it, but if you do it yourself you will need to learn a lot. The grounding issues are very important, and the terminology used creates a lot of confusion with very similar sounding acronyms and terms that mean very different things in different contexts.


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## timothy300858 (Mar 10, 2014)

I had a bigger panel put in not to long after I purchased the home by a licensed electrican who did it for a side job... He has actually been really cool with me and told me it would be no prob adding a subpanel if I needed one.. We weren't sure at first I would need so many but he said same thing.. Its not too hard to do but why not let him do it ya know for a couple bucks...


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## dgfit (Jun 5, 2013)

timothy300858 said:


> I had a bigger panel put in not to long after I purchased the home by a licensed electrican who did it for a side job... He has actually been really cool with me and told me it would be no prob adding a subpanel if I needed one.. We weren't sure at first I would need so many but he said same thing.. Its not too hard to do but why not let him do it ya know for a couple bucks...


 Would be money well spent given he is licensed


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## dgfit (Jun 5, 2013)

Ok - now for a biggie - have you considered AFCI breakers? They are code required for some circuits.


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## timothy300858 (Mar 10, 2014)

I did read alittle about them today but nothing more than that... Im not quite sure if I totally understand the spots in the house that they would come in handy for... I know they are breakers used to trip whenever there is an arc in the line.. correct??


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## dgfit (Jun 5, 2013)

Well the code requires them in various circuits depending on the code cycle. NEC is published every 3 years and is adopted by local jurisdictions. My city defers to state, which is currently on the 2011 cycle. The 2014 cycle was just recently published. AFCI breakers have been around for a while and the rooms where they have required have increased to the point where 2014 requires them almost everywhere. Would need to research your specific area to know exactly what the requirements are.

I have not yet lived with AFCI breakers in my home, but I personally love the concept. They have a chip inside with programming that is intended to detect a normal arc from a dangerous arc. Evidentially, there has been a history of false trips that result in repeated (free) service calls to electicians. It seems the false trips are due to a few issues including early versions were just not as good, but also certain wiring methods have caused problems. The lesson I learned from this as a DIYer is to simply be as simple and straightforward with the wiring as possible. I am not using a MWBC (multi wire branch circuit) anywhere. Also will make sure the neutrals in all connections remain exclusively on the circuit and leg carrying the hot to which they are associated.

In addition, these breakers are expensive. Normal breakers are typically less than $10 each, but AFCI breakers are $35-40. In my case, one of my biggest expenses will be AFCI breakers. I am putting them in just about every lighting and outlet circuit that does not require GFCI.

The cost is hard for electricians to recoup and combined with the free service calls resulted in "hatred" by sparkles . Of course, this is all just my observations and opinions


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## dgfit (Jun 5, 2013)

One other thing to consider is that AFCI breakers not only detect arcs in the romex, but also in whatever is plugged in. So that lamp cord that gets crunched by the rocking chair that starts to arc. Keep in ind that arc is just like an electric pilot lite that is intended to start a fire.


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## timothy300858 (Mar 10, 2014)

Yeah , that is something I will have to do research on.... As far as the wiring goes, the only thing that I did differently is pigtailed the outlets.. I was told by my guy to do that so when one outlets (if) goes bad, the rest still are working... But I think when I wire in everything upstairs , Im just going to do the normal wiring thing... Your MWBC is a new term for me.. Ive never seen or heard it before.. Any examples?? I had to have my guy come back and wire in the 12/3 because I wasn't quit sure of the way it is supposed to be used.. Im still learning lol


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## dgfit (Jun 5, 2013)

An MWBC would have a 14/3 or 12/3 cable in the breaker panel with black hooked to one breaker and red hooked to another breaker and the white connected to the neutral bus. One typical use was for those two kitchen SABCs where one SABC is fed by the black, the other is fed by the red, and they share the neutral.

Whatever you do - if you have any of these then be extremely careful not to disconnect the neutral on that circuit anywhere or you could fry any equipment plugged into it!!! This goes for the breaker panel and any junction boxes. Leave that neutral intact. Also, if you do work on one of these, be sure to turn off both breakers (code now requires the breaker handles to be tied together but that was not always the case).

The principal behind how MWBC circuits work is rooted in how AC power distribution services work in general. If you note that the two conductors from the pole are connects to the two lugs in your panel, and then note that those lugs are connected to interleaving "fingers" to which the breakers attach. And then the neutral from the pole is attached to the neutral bus. So then a MWBC is effectively just a continuation of those conductors. In that setup, if you disconnect the neutral you have then turned those 120 volt outlets into 240 volt outlets - which will fry most anything plugged into them.


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## timothy300858 (Mar 10, 2014)

Well now Im kinda worried because Im pretty sure I have that in my panel.. We used 12/3 for a 3 way switch for lights and it was used into the bathroom to control the light/exhaust fan set up (I think)... Id have to go look to make sure...


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## dgfit (Jun 5, 2013)

Pig tailing is good too - in the little wiring I did prior to my self education, I never did it. But I am now with my rewire. One other item I researched - the NFPA did a study (related to AFCI breakers interestingly enough) that found the leading cause of electrical fires in properly installed systems is when a cable is hit by a hammer during install and years later causes a weak spot in the insullation. To me, this is one area where knowledge cannot make up for lack of experience. Sparkles who do this day in and day out know how to drive a wire staple without damaging a wire. I don't have that benefit, so instead, I bought myself a good NM cable stapler that uses insulate staples.


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## timothy300858 (Mar 10, 2014)

So I just looked and yep, it is wired like that 2 different times... Anything to worry about??? One line is ran for the bathroom like I said and the other feeds the lights and some outlets if I can read my writing lol..


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## dgfit (Jun 5, 2013)

timothy300858 said:


> Well now Im kinda worried because Im pretty sure I have that in my panel.. We used 12/3 for a 3 way switch for lights and it was used into the bathroom to control the light/exhaust fan set up (I think)... Id have to go look to make sure...


Having 14/3 or 12/3 for a 3 way switch does not indicate a MWBC. It would have to be in the panel. It's perfectly safe, but it's one of those things that cause the pros here to advise some to not tackle jobs themselves. Just so so many things to consider - and it can be dangerous. It's DIY able - but there is a lot to learn to do it safely.


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## timothy300858 (Mar 10, 2014)

I was just saying it was like that in the panel.. If that's what you meant.. I have a red and a black going into two separate breakers and the neutral and ground are together in the same spot.. I have that twice.. Maybe Im confused...


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## dgfit (Jun 5, 2013)

timothy300858 said:


> So I just looked and yep, it is wired like that 2 different times... Anything to worry about??? One line is ran for the bathroom like I said and the other feeds the lights and some outlets if I can read my writing lol..


If that's in the panel then yes it sounds like you have a MWBC and would like to hear from the pros about a MWBC used in a bathroom. Is that allowed?

Like I said - be very careful with the neutrals. Turn both breakers off when you do anything with either of those circuits.


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## dgfit (Jun 5, 2013)

timothy300858 said:


> I was just saying it was like that in the panel.. If that's what you meant.. I have a red and a black going into two separate breakers and the neutral and ground are together in the same spot.. I have that twice.. Maybe Im confused...


 (Our posts are crossing each other  ) Yep - the black, red, and white are part of a MWBC. Just be careful with the neutral in all parts of the circuit and make sure you turn off both breakers when working with that circuit. It's expected that the ground and neutral are connected - that is another whole discussion related to the grounding issues mentioned in my subpanel post.

Edit - corrected above to say black, red, white


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## timothy300858 (Mar 10, 2014)

Ill have to ask my guy also what he thinks of the situation.. Im assuming he wouldn't do anything that wouldn't be right or cause any trouble... Its either that or he knows I wouldn't do anything with it ... Im not a huge fan of poking around in the panel but I did change breakers.. Not to sound like a sissy but that's about as far as Ill go lol.... The only thing I can think of is , there is going to be two lights in the bathroom... The light above the sink is getting its power from the line from the bedroom lights .. and the 12/3 was used solely for the light/exhaust fan so I can have separate switches to turn them on/off... And the GFI is on its own circuit .. I do remember him bringing over a line for the light switch..


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## dgfit (Jun 5, 2013)

Well I should note that 240 circuits will also have wires going to two breakers - such as for a dryer, AC unit, electric stove, electric furnace or electric hot water heater. They are not MultiWireBranchCircuits because they feed a single device. But your bathroom circuits sound like MWBC.


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## dgfit (Jun 5, 2013)

timothy300858 said:


> Ill have to ask my guy also what he thinks of the situation.. Im assuming he wouldn't do anything that wouldn't be right or cause any trouble... Its either that or he knows I wouldn't do anything with it ... Im not a huge fan of poking around in the panel but I did change breakers.. Not to sound like a sissy but that's about as far as Ill go lol.... The only thing I can think of is , there is going to be two lights in the bathroom... The light above the sink is getting its power from the line from the bedroom lights .. and the 12/3 was used solely for the light/exhaust fan so I can have separate switches to turn them on/off... And the GFI is on its own circuit .. I do remember him bringing over a line for the light switch..


Again MWBC circuits have been common place - just require a bit more knowledge and experience to work with them. But they also cause problems for AFCI breakers.


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## timothy300858 (Mar 10, 2014)

But wouldn't an exhaust fan/light combo be considered a single device???


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## timothy300858 (Mar 10, 2014)

Well I was just looking in the panel and the one 12/3 that supplies the bathroom GFI also supplies the washer/dryer GFI's that are on the other side of that same wall... Well atleast I have one labeled washer/dryer and the other bathroom GFI... And there is 12/3 up for the exhaust fan/light in the bathroom obv going into the spot for the switch.. so that is possibly involved also... I had him rough everything in and all I had to do was hook up receptacles and switches... and obv light fixtures also....


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## dgfit (Jun 5, 2013)

timothy300858 said:


> But wouldn't an exhaust fan/light combo be considered a single device???


For that, I would have expected a 14/2 or 12/2 going to a single switch box with the black connected to two switches and then possible 14/3 or 12/3 going to the fan/light. But here is an area where I may not have enough experience to know all of the possibilities.

The real point is that if you measure voltages from one of the hots from the pole to the other hot from the pole you get 240 volts. So devices that require 240 volts will have two wires connected to two different breakers. Now if you measure from either of the hots to the neutral then you get 120'volts, which is what is needed by things like the light/fan. So as long as the neutral is intact, you have 120 volts. If you remove the neutral, then you get 240.

Sparkles like MWBC circuits because it means less cable and less labor. Rather than running two 12/2 wires for two different circuits with each having its own neutral, they can run one 12/3 cable and share the neutral.


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## timothy300858 (Mar 10, 2014)

dgfit said:


> For that, I would have expected a 14/2 or 12/2 going to a single switch box with the black connected to two switches and then possible 14/3 or 12/3 going to the fan/light. But here is an area where I may not have enough experience to know all of the possibilities.
> 
> The real point is that if you measure voltages from one of the hots from the pole to the other hot from the pole you get 240 volts. So devices that require 240 volts will have two wires connected to two different breakers. Now if you measure from either of the hots to the neutral then you get 120'volts, which is what is needed by things like the light/fan. So as long as the neutral is intact, you have 120 volts. If you remove the neutral, then you get 240.
> 
> Sparkles like MWBC circuits because it means less cable and less labor. Rather than running two 12/2 wires for two different circuits with each having its own neutral, they can run one 12/3 cable and share the neutral.


that last bit of your comment sounds familiar.. I remember my guy saying something like that lol


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## dgfit (Jun 5, 2013)

timothy300858 said:


> Well I was just looking in the panel and the one 12/3 that supplies the bathroom GFI also supplies the washer/dryer GFI's that are on the other side of that same wall... Well atleast I have one labeled washer/dryer and the other bathroom GFI... And there is 12/3 up for the exhaust fan/light in the bathroom obv going into the spot for the switch.. so that is possibly involved also... I had him rough everything in and all I had to do was hook up receptacles and switches... and obv light fixtures also....


 Right - so the 12/3 from the panel is a MWBC with one hot (black or red) feeding the outlets in the bathroom and the other hot feeding the outlets in the laundry room. I would assume that the hot feeding the bathroom is connected to two switches for the light and fan which is then connected to the light/fan with 12/3. This last 12/3 is not part of the MWBC because it is all fed from the same breaker.

Edit - replaced the last part to say "same breaker"


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## timothy300858 (Mar 10, 2014)

I honestly think that is how it is.. Are you sure you didn't do the rough in??? And like I said before, Im assuming he did all this knowing it was okay to do.. Meaning not putting my house in harms way... There is another one in the panel I have listed for lower level lights in the main living room and outlets in same room.. which also has a 3 way switch for those exact lights.... One switch is by the door going into the garage and the other cross the room... Im gonna go out on a limb and say I don't think I will have all that craziness for the upstairs... Who knows, I do have one 3 way that needs to get some power to lol


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## timothy300858 (Mar 10, 2014)

And if he has that 12/3 running to a switch for the exhaust fan/light, I guess Ill have to get a different switch then just a single up/down huh?? Something with a double switch... I don't even remember making that decision but ...I just took a look and I think I have it wired wrong for the switch that powers the light above the sink.. I have 2 blacks hooked in the switch and one goes with the 12/3... and he had it labeled light along with labeling the red for exhaust.... So I might have to undo the one black and use it for the double switch I mentioned earlier??? Or can I leave it plugged into the switch that controls the sink light and it will just turn on when I flip that switch??? Meaning there will only be a switch for the fan left??? By the way, there isn't anything installed but a cheap light bulb above the sink just for now...


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## dgfit (Jun 5, 2013)

timothy300858 said:


> I honestly think that is how it is.. Are you sure you didn't do the rough in??? And like I said before, Im assuming he did all this knowing it was okay to do.. Meaning not putting my house in harms way... There is another one in the panel I have listed for lower level lights in the main living room and outlets in same room.. which also has a 3 way switch for those exact lights.... One switch is by the door going into the garage and the other cross the room... Im gonna go out on a limb and say I don't think I will have all that craziness for the upstairs... Who knows, I do have one 3 way that needs to get some power to lol


No not me - just what I have learned in that 2-3 months of studying I mentioned reading a couple of books, studying the code and reading these posts 

It is ok and perfectly safe - just require knowledge and understanding to work with them. Personally, I am not concerned about running another cable so I'm not messing with MWBC circuits - also because I don't want to cause issues with AFCI breakers.

Please know that a MWBC circuit is not related at all to three way switches.


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## dgfit (Jun 5, 2013)

timothy300858 said:


> And if he has that 12/3 running to a switch for the exhaust fan/light, I guess Ill have to get a different switch then just a single up/down huh?? Something with a double switch... I don't even remember making that decision but ...I just took a look and I think I have it wired wrong for the switch that powers the light above the sink.. I have 2 blacks hooked in the switch and one goes with the 12/3... and he had it labeled light along with labeling the red for exhaust.... So I might have to undo the one black and use it for the double switch I mentioned earlier??? Or can I leave it plugged into the switch that controls the sink light and it will just turn on when I flip that switch??? Meaning there will only be a switch for the fan left??? By the way, there isn't anything installed but a cheap light bulb above the sink just for now...


We are gonna have to spend some time with this one - and I'm sorry but my wife is yawning and we are about turn I to pumpkins . Would it be possible for you to post some pics of the panel showing these circuits, and the outlet / switch wiring involved? That would help me out all of what you have described in context and we can pick it up again tomorrow?


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## timothy300858 (Mar 10, 2014)

If I knew how to post pics I def would.. But tomorrow will be just fine.. I will explain it alittle better then.. have a good night


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## iminaquagmire (Jul 10, 2010)

I'm having trouble following you on this too, but I think what you're explaining is a feed to the fan/light from the switch. Its just easier using a 12/3 wire rather than two separate 12/2's. One wire in the switch box is your constant hot. It gets pigtailed to two switches or a double. The other terminal on each switch gets connected to the red or black going to the fan/light.


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## timothy300858 (Mar 10, 2014)

Okay.. I have to put in two switches.. one controls the light above the sink and the other controls the exhaust fan/light in the ceiling.. In the gang box, have 2 blacks (one labeled light) and 1 red (labeled fan)... Right now I have both blacks hooked to the switch for the light above the sink (which I think Ive done it wrong). Shouldn't I have the red and black that are labeled going to a double switch for the fan/light in the ceiling and the single black going to the switch for the light above the sink??? Make sense yet? LOL


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## timothy300858 (Mar 10, 2014)

Did I confuse both of you guys last night???


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## dgfit (Jun 5, 2013)

Will take a look in a few hours (got my day job  )


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## dgfit (Jun 5, 2013)

timothy300858 said:


> Okay.. I have to put in two switches.. one controls the light above the sink and the other controls the exhaust fan/light in the ceiling.. In the gang box, have 2 blacks (one labeled light) and 1 red (labeled fan)... Right now I have both blacks hooked to the switch for the light above the sink (which I think Ive done it wrong). Shouldn't I have the red and black that are labeled going to a double switch for the fan/light in the ceiling and the single black going to the switch for the light above the sink??? Make sense yet? LOL


There is a thread in the forum support section that explains how to upload your photos.

Can you describe all wires you have in the box and where they come from / go to? I would expect:

1. Feed bringing power to the box (would be a bare ground, white neutral, and either a black or red hot)
2. Cable to fan/light (would expect black, red, white, ground)
3. Cable to sink light (would expect black, white, ground)

It sounds like right now, you have

one switch that controls both the sink light and fan light
one switch that controls the fan

Nothing wrong with that, but if it were me, I would rather have either what you describe:

One switch for the sink light
One switch for the fan light
One switch for the fan

Or this:

One switch for the sink light
One switch for the fan light and fan


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## timothy300858 (Mar 10, 2014)

Sorry for the delay... Im work 12's and I pretty much just sleep and work lol... Let me get back to you tomorrow after I get home and I will try my best to explain what I see.. Thanks


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## timothy300858 (Mar 10, 2014)

But I totally agree with you.. I would rather much have a switch for the sink light, switch for the fan and a switch of the light that is with the fan.. 2 technically 3 switches... What I was saying was I think I have it wired up right now as both lights would come on under one switch seeing that I have both blacks in the same switch and only one other hot being the RED one to power the exhaust fan...


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## dgfit (Jun 5, 2013)

Sounds good - take a look at that thread for uploading pics - would help a ton.


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## timothy300858 (Mar 10, 2014)

okay ... here we go... I was just down there looking at everything that's in the box... This is what I see... there are 4 sets coming into the box... One being 12/3 going up to the exhaust light/fan in the ceiling, 1 12/2 coming from the bedroom light switch and one 12/2 going to the light above the sink... As far as the 4th set, I cant tell where its coming from (drywalled in)... I see all the neutrals nutted together, there are two sets of blacks nutted together, and then there is a red and another single black that are usable... Right now, I have one switch hooked up which controls the light above the sink.. Now , my elelctrician guy has the red wire labeled (exhaust) and one of the blacks labeled (light which is from the 12/3)... In that one switch that is there, Im using 1 black from one of the groups and then the black labeled (light)... So that leaves a red and a single black that isn't nutted with any other ones... Those two lines are NOT from the same feed... I tried using that single black in the switch instead of the one labeled (light which is from the 12/3 ), and the light wouldn't work.... So Im back to the same thing.. two blacks into the switch and one red and a black still needing to be used... So do I use a double switch and use the red for one and the black for the other (ceiling light and exhaust fan) hots... Make any sense?? Im sure its confusing to ya now


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## UnclePhil (Mar 4, 2014)

timothy300858 said:


> Im sure its confusing to ya now


got that right....

I'm thinking... you should have a feed into that switch box and maybe a feed or two out...

those hots,neutrals and grounds would be spliced (not all together)..

from that hot you would have spliced pigtails to feed your switches how ever many there are.

Your switch legs out to your lights and fan..

the single light hot would go to a switch. neutral spliced to feed in out neutral.
the fan light (3 wire)... probably black to switch for fan, red to switch for
the light (or the other way around).that neutral to feed neutral in and out.
(they could be two switches, or an under over type switch)

other than that..

???


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## timothy300858 (Mar 10, 2014)

That is where I was getting confused... My thing is .. hows come I cant use the two hots from the 12/3 for the fan and light combo (over/under switch) and the single black hot for the sink light..... But when I changed the two blacks in the switch that is there, it wouldn't light... So im actually using a single black hot and the black from the 12/3 in the sink light switch.. So im assuming when I actually install the fan/light, both the lights will come on with that switch and then (red and black ) that's left will be used in the fan switch ...Im assuming the black hot for that switch is exactly that.. the hot supply and the red just runs the power up to the fan...


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## Jim Port (Sep 21, 2007)

Sure doesn't sound like your electrical guy is too sharp. Maybe they should ask the carpenter.


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## timothy300858 (Mar 10, 2014)

Sure doesn't sound like you don't have anything to say that is worth listening to.. Thanks but no thanks!!!


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## UnclePhil (Mar 4, 2014)

timothy300858 said:


> That is where I was getting confused... My thing is .. hows come I cant use the two hots from the 12/3 for the fan and light combo (over/under switch) and the single black hot for the sink light..... But when I changed the two blacks in the switch that is there, it wouldn't light... So im actually using a single black hot and the black from the 12/3 in the sink light switch.. So im assuming when I actually install the fan/light, both the lights will come on with that switch and then (red and black ) that's left will be used in the fan switch ...Im assuming the black hot for that switch is exactly that.. the hot supply and the red just runs the power up to the fan...


What happened to the electrician...

do you have a electricity 101 book..

not busting horns..just asking..


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## timothy300858 (Mar 10, 2014)

Well I think Im going to call him anyways because Im going to need a subpanel put in... I will see what he says with it.. Kinda sucks its all drywalled now.. Guess I should have installed a switch before closing it all up lol.. Ill figure it all out.. thanks.. any suggestions on a good book to just pick up for some helpful reading???


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## sirsparksalot (Oct 16, 2010)

Timothy,

You have a light above the sink, and you have an exhaust fan with light. You're using over/under switches.

So, you need to have the feed coming in somewhere. I assume it's one of the 2-wire cables. This 2-wire cable consists of the Hot and Neutral. The Hot in this cable is going to have to terminate on one side of the switch. 

_(I'm thinking there are 3 screws on the switch, yes?)_ Now, you have a 3-wire going to the exhaust fan/lite. The Black from this cable will terminate on the other side of the over/under switch. The Red will also terminate on the other side of the switch. I believe there's a tab on the load side of the switch which you will break off in order to separate the switches to their respective loads.

You have a 2-wire cable going to the light over the sink, correct? Then you will need to hit one side of a single-pole switch with this cable's Black wire, and the other side will have a pigtail from the Hot Black terminated on the other side of the switch.

As a test, find the feed cable (the one that shows 120v between its Black and White). Assuming the Neutrals are connected, take the Hot wire and connect it, one at a time, to each of the other Blacks, and then to the Red: this should turn your lights and fan on.

Make sense?

For testing purposes, take the


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## timothy300858 (Mar 10, 2014)

I think I understand everything you are talking about .. But one problem.. The sink light is the only thing that is even installed.. I guess I will revisit this when its time... Was just trying to get ahead of the game ... Thanks though


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## sirsparksalot (Oct 16, 2010)

OK, just the sink light for now.

You will need a feed into the switch box. This will be a 2-wire cable coming from a source (_panel?_). Then, you will need a 2-wire cable going to the light. The wiring is simple: take the White wires and wirenut them together. Take the Black from the source, and terminate on one side of a single-pole switch, take the Black that is going to the light, and terminate it on the other side of the switch. Simple; when the switch is closed, current goes to the light, when it is open, current stops.

How's that?


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## timothy300858 (Mar 10, 2014)

No offense, but Im way past knowing how to wire up a single switch... In case you haven't read my previous posts, my problem is much further than that... But Ive given up on most of you guys because Im better off.. thanks for the "supposed" help but Ill find it elsewhere.. Take care and have a great day!!!


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## iminaquagmire (Jul 10, 2010)

You don't seem like you're way past it. Myself and these other guys have spent a lot of time helping you and anytime you get advice the slightest bit astray from what you think you know or your "electrician" did, you belittle the very people who you've asked for help. You may think you aren't but you are. You've repeatedly asked the same questions, and I don't know if you're hoping for different answers or just not listening, but they've all been graciously answered. I'm glad you're farther away from me because I'd hate to have to come behind you at some point. I'm done with my "supposed" helping you because you're too hardheaded to listen.


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## diynewguy (Mar 26, 2014)

Actually, Ive read this whole thread and it sounds like to me that he's just someone looking for answers worded a different way... You guys are kind of rough with him which isn't fair to him either... But Im just a nobody diy'er who has his own issues..


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## sirsparksalot (Oct 16, 2010)

diynewguy said:


> Actually, Ive read this whole thread and it sounds like to me that he's just someone looking for answers worded a different way... You guys are kind of rough with him which isn't fair to him either... But Im just a nobody diy'er who has his own issues..


7 pages of wiring a bathroom light and fan/light, and he's still here. I'm done.


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## diynewguy (Mar 26, 2014)

Well all I can say is some people don't catch on to things as well as others... Im not taking anyone's side but I definitely think some of you were being kind of harsh. Just my opinion. He's a beginner like me obviously so maybe a little slack is needed


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## kwikfishron (Mar 11, 2010)

diynewguy said:


> Well all I can say is some people don't catch on to things as well as others... Im not taking anyone's side but I definitely think some of you were being kind of harsh. Just my opinion. He's a beginner like me obviously so maybe a little slack is needed


From our "Terms of Service"


> k) By using this site, you agree to maintain and use only one account. If you need to re-register for some reason, please contact a member of the Moderation Team. If you are found to have more than one user account, it will be evaluated by the Admins and will likely result in banning. As always, there are extreme exceptions that will be looked into at the Admins’ discretions.


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## buddy builder (Jul 26, 2009)

sir, none of the advice i saw given to you was bs. when you deal with electricity you need to be safe, not sorry. i have a basic knowledge of electricity and love to read all these threads and answers to them. i cannot spend ten minutes with these guys and not learn something every day. some of these guys have forgot more than i could ever hope to learn. one thing i feel i sense from your frustration is that you seem to be worried about the 15 amp breakers. these breakers are meant to protect you. don't be afraid of them. they are there for you and your family for your protection. in a nutshell, are you having trouble with any of these 15 amp breakers tripping? whatever your answer is will tell you which road to take.


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