# Panel Replacement/Upgrade 400 Amp



## AndrewF (Dec 29, 2008)

I pulled a permit a few months ago to do a panel swap (200amp) and replacement the ground mount meter base with a wall mount.

I haven't started the project yet for several reasons, but now that winter has arrived, I figure it is a good winter project.

The current panel is a push-o-matic panel and is a disaster. It buzzes and hums when things like the microwave or other appliances are on.

I contacted the local electric utility and asked about upgrading to 400 amp service. They said it would be no problem from a plant perspective. Everyone I have talked to suggested to upgrade to 400 amp service since the cost to do so now is minimal compared to me deciding to do it later.

Background
Main panel (200 amp)
Sub-panel (100 amp) new in basement

I built a 40'x68' barn/workshop and will be running 60-100 amp service to it in the spring.

Can I install a 400 amp dual tap meter socket and then split two 200 amp feeds to two 200 amp panels in the garage without having any exterior shutoffs? These two panels would be on the opposite wall of the meter and require runs less than 8'.

One panel would have all the existing wiring the old one does. The second panel would have the 100 sub-panel and the 100 amp panel to the barn. (Note the 100 amp sub-panel sees max loads of 80 amps when the backup electric heat is on)


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## Gigs (Oct 26, 2008)

I'm not sure how you sleep at night with that thing in your house.


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## Speedy Petey (Feb 1, 2004)

Sounds like a fine idea. What you are referring to is a 320/400 amp service. 
Rated at 400 amps, but 320 amp continuous. The meter pan is actually a 320A meter pan and the POCO uses a regular plug-in meter.


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## AndrewF (Dec 29, 2008)

Here is a photo of the panel location in the garage. The old panel is on the right, the future new panel is on the left.

My thought is instead of moving all the circuits from the panel on the right to the panel on the left, is to just put a new panel in the location of the old and leave the panel on the left for the sub-panel to the basement (100 amp) and 100 amp to the barn.

What I want to avoid is having a bunch of clutter on the outside wall of the garage outside of the conduit to bring the underground service up to the meter box and then the two 200 amp feeds to the new panels.


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## InPhase277 (Feb 9, 2008)

I too would upgrade. Your plan seems ok, but check back in with questions. I personally like to have disconnects on the outside of the structure, but short back-to-back runs are fine.

Also, I want to say, you guys are really hard on old services! With a little TLC and some clean up and torquing, alot of old service panels can be made like new.


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## AndrewF (Dec 29, 2008)

InPhase277 said:


> Also, I want to say, you guys are really hard on old services! With a little TLC and some clean up and torquing, alot of old service panels can be made like new.


Well, what started this all was my plan to put 100 amp service into my workshop and having to put 100 amp sub-panel in the basement for the 20KW backup heat. This push-o-matic panel is full, was overstuffed and it would cost around $100 for a 100 amp breaker alone.

The pedestal being ground mounted since 1977 and they have a tendency to rust out and collapse and with it missing the glass front plate to keep little hands and arms out of it...were a few of the reasons I decided to do a panel swap...from there the project just kept growing.

One of the things I hope to get rid of is that when the 5 ton heat pump kicks on, the house lights dont all dim! That annoys me.


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## nap (Dec 4, 2007)

> Can I install a 400 amp dual tap meter socket and then split two 200 amp feeds to two 200 amp panels in the garage without having any exterior shutoffs? These two panels would be on the opposite wall of the meter and require runs less than 8'.


IF the panels are next to each other, this is legal. If they are not right next to each other (like you cannot have to take a step to reach the second panel), you will have to have a main disconnect somewhere.


Each panel has to have a main breaker in this type of install.

Now, you may run into a problem with the distance inside the building. It seems every inspector has his own allowances. Check with him before actually installing.

Oh, and you will have to get rid of that bench in front of the panels. You have to have 3 ft clear space in front of a panel and 30 inches or the width of the panel(s) (whichever is ggreater) side to side.


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## InPhase277 (Feb 9, 2008)

Andrew, I agree you should upgrade your service. My comment on old services was about how every question about an old service automatically turns into a "Rip it out" thread, but sometimes that isn't practical or affordable for some. There are often options other than "rip it out".



AndrewF said:


> One of the things I hope to get rid of is that when the 5 ton heat pump kicks on, the house lights dont all dim! That annoys me.


Bad news! You may not solve this by upgrading! This is usually due to voltage drop on the utility's conductors. So unless the power company runs extra large conductors to your new service (not likely), you will still have some dimming when the heat pump kicks in.


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## Speedy Petey (Feb 1, 2004)

InPhase277 said:


> Bad news! You may not solve this by upgrading! This is usually due to voltage drop on the utility's conductors. So unless the power company runs extra large conductors to your new service (not likely), you will still have some dimming when the heat pump kicks in.


Ah yes. It is a very common misconception that a service upgrade will cure ailments such as that and also breakers tripping. It can be very hard trying to explain to a customer that the service size has no bearing on those things.
Sure, things like splitting up a double tapped breaker will help, but a service is not a cure-all for electrical problems in the house.


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## AndrewF (Dec 29, 2008)

I have a dedicated transformer for my house, buried extremely close to the house (IMHO). The transformer is fed 7500 volts from the main line from the road. The distance from the transformer to my meter will be approximately 60 feet. I had the electric companies engineer come out and make sure the transformer would support 400 amp service, it will. They will run new cable from the transformer to my meter socket, even if I only do 200 amp service. I can't find my notes, but I believe he said they'd run 000.

I had thought about running larger wire to the outdoor unit as well and instead of running it off of the garage panel (~90' run) to run it off of the 100 amp sub-panel in the basement, which would be a 40' run.


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## jamiedolan (Sep 2, 2008)

AndrewF said:


> I have a dedicated transformer for my house, buried extremely close to the house (IMHO). The transformer is fed 7500 volts from the main line from the road. The distance from the transformer to my meter will be approximately 60 feet. I had the electric companies engineer come out and make sure the transformer would support 400 amp service, it will. They will run new cable from the transformer to my meter socket, even if I only do 200 amp service. I can't find my notes, but I believe he said they'd run 000.
> 
> I had thought about running larger wire to the outdoor unit as well and instead of running it off of the garage panel (~90' run) to run it off of the 100 amp sub-panel in the basement, which would be a 40' run.


3/0 in AL I am sure, which would be the same as 2/0 copper (I think that's the right conversion). Which really sounds a bit undersized to me for 200A for a 60' run. Service cables from the power co are sized differently and the NEC does not apply to them. So I don't know all the details.

What I do know if that often the connection from the transformer to your house is the connection that is to blame for voltage drop and is the reason behind much of the light flicker type problems. If it where my house, I'd be mounting a pedstal meter with a disconnect (so the service is fused right away) right there in the yard as close to that transformer as they would allow it. I hate seeing unfused cable, and most inspectors won't allow it to be run very far anyway, it's just too dangerous if someone ever hits it. 

Then I would run 3/0 THHN (I would think about 4/0 if it was affordable to compensate for voltage drop) into the house in conduit from that pedstal meter / disconnect setup for 200A service.

Just some thoughts from me. I am sure Inphase or one of the other guys will correct me or add to this if I am mistaken on any of it.

Jamie


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## AndrewF (Dec 29, 2008)

The county wont permit a pedestal meter like I have now, they want me to replace it, so does the electric company.


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## jamiedolan (Sep 2, 2008)

AndrewF said:


> The county wont permit a pedestal meter like I have now, they want me to replace it, so does the electric company.


Ok, How about on the corner of the house that looks to be about 10' away from the transformer. Either on the side by the door or on the other side by where the gutter is? Is that only about 10'?

If you want the best chance possible of getting rid of or minimizing the light flicker from high amp start ups, then you want to get as close the power co feed (that transformer) as possible. 

I can't tell exactly now from your first photo, but it kind of looks like you have expose cable run from your box up over your door then back down into your house, is that correct?

Jamie


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## AndrewF (Dec 29, 2008)

The existing panel and all wiring terminates in the garage, on the opposite side of the wall where i made the red meter marking in the photo. It would be cost prohibitive to move the panel anywhere else.

Any new wiring between the house and the garage has to go through conduit on the outside of the house as there is no other way (short of tearing walls apart) to get the feed to the basement.


Here are two more photos from a different angle.


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## Speedy Petey (Feb 1, 2004)

Why is there a giant onion on your roof???


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## jamiedolan (Sep 2, 2008)

AndrewF said:


> The existing panel and all wiring terminates in the garage, on the opposite side of the wall where i made the red meter marking in the photo. It would be cost prohibitive to move the panel anywhere else.
> 
> Any new wiring between the house and the garage has to go through conduit on the outside of the house as there is no other way (short of tearing walls apart) to get the feed to the basement.
> 
> ...


You can leave the panel there. What I am suggesting is to install the meter and a disconnect at the end of the house, very close to the transformer. Then, just bury conduit over to the garage where it needs to go to the panel. 

Then the power co's feed is only a few feet from the transformer to the corner of the house.

Jamie


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## AndrewF (Dec 29, 2008)

jamiedolan said:


> You can leave the panel there. What I am suggesting is to install the meter and a disconnect at the end of the house, very close to the transformer. Then, just bury conduit over to the garage where it needs to go to the panel.
> 
> Then the power co's feed is only a few feet from the transformer to the corner of the house.
> 
> Jamie


I am not sure what this accomplishes other than me now having to absorb the cost from the corner of the house to the main panel in the garage.

As it stands now, the utility company is responsible for the cable from the transformer to the new meter and has already told me they would run new cable regardless of wether I go 200 amp or 400 amp.

It seems to me that if I go 400 amp, it forces(ensures) they run larger cable anyways and would minimize any voltage drops.


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## jamiedolan (Sep 2, 2008)

AndrewF said:


> I am not sure what this accomplishes other than me now having to absorb the cost from the corner of the house to the meter.
> 
> As it stands now, the utility company is responsible for the cable from the transformer to the new meter and has already told me they would run new cable regardless of weather I go 200 amp or 400 amp.
> 
> It seems to me that if I go 400 amp, it forces(ensures) they run larger cable anyways and would minimize any voltage drops.


The power co does as they wish. NEC does not apply. You can order and install the larger service, They may put in a new cable, but I highly doubt they going to put in a a cable large enough to handle the voltage drop.

Your right it is going to cost you a lot more to install as I suggested. It really comes down to how much you care about the voltage drop and the light flickering issue. 

Did they tell you they would size the cable differently for 400a service? 

Jamie


:jester::thumbup:*Post #1,000 on DIYCHATROOM.COM!!!!*:thumbup::jester:


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## chris75 (Aug 25, 2007)

Speedy Petey said:


> Why is there a giant onion on your roof???


Looks like a water tower in the background?


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## Speedy Petey (Feb 1, 2004)

chris75 said:


> Looks like a water tower in the background?


Well I like to see it as an onion. OK? :whistling2:


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## chris75 (Aug 25, 2007)

Speedy Petey said:


> Well I like to see it as an onion. OK? :whistling2:


 
 It is a funny picture.


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## AndrewF (Dec 29, 2008)

jamiedolan said:


> Did they tell you they would size the cable differently for 400a service?
> 
> Jamie


Yes, they did. I spoke to the chief engineer. He said he'd drop in new wire and would most likely go ahead and drop in cable big enough for 400 amp service so that i don't have to go through all of this again, but if I did upgrade to 400 amp they would definitely run big enough wire to service it.

My thought is that if I install 400 amp service, and they install bigger wire, and I only need peak 250 amps of service...I shouldn't necessarily have the voltage drop issue.

--------

Yes, it is a water tower across the street that looks like an "onion".


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## jamiedolan (Sep 2, 2008)

AndrewF said:


> Yes, they did. I spoke to the chief engineer. He said he'd drop in new wire and would most likely go ahead and drop in cable big enough for 400 amp service so that i don't have to go through all of this again, but if I did upgrade to 400 amp they would definitely run big enough wire to service it.
> 
> My thought is that if I install 400 amp service, and they install bigger wire, and I only need peak 250 amps of service...I shouldn't necessarily have the voltage drop issue.
> 
> ...


I understand, and In theory what you have planed sounds good in concept and may work out well...

As far as I know 400A service is normally protected at a max of 320A, so if you peak out at 250A of use, your still using around 80% of your service capacity.

Motors use such a huge amount of power at start up that you have to really go out of your way to size the conductors big enough that you don't get the dimming / flicker form a motor start up, especially from a load as big as a heat pump. 

Even really small voltage drops cause flickering / dimming in lighting, and we are able to see those really small changes.

If they put in a larger cable, it should help, but they don't care if your lights dim or flicker and are not likely to size ($$$ to run that large of a cable) to prevent the voltage drop.

If you really want to get rid of the flicker / dimming, putting the meter / a disconnect really close to the transformer is the answer (then running the necessary size cable, possibly a dedicated cable to the heat pump,,, again that is only if you really care about getting rid of the flicker). 

Running the large cable yourself would be expensive. So unless the light dimming really bothers you, then you mind as well let the power co run it to the garage, then you just have the short run in.

Jamie


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## chris75 (Aug 25, 2007)

AndrewF said:


> My thought is that if I install 400 amp service, and they install bigger wire, and I only need peak 250 amps of service...I shouldn't necessarily have the voltage drop issue.
> 
> --------


Do not count on it, Power Companies know what residential loads actually are, not like the NEC which is WAYYYYYYY overkill, so you will IMO still have lights dimming, but you can always invest in a hard start kit.


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## chris75 (Aug 25, 2007)

jamiedolan said:


> I understand, and In theory what you have planed sounds good in concept and may work out well...
> 
> As far as I know 400A service is normally protected at a max of 320A, so if you peak out at 250A of use, your still using around 80% of your service capacity.
> 
> ...


Jamie, I know you mean well and your care shows, but moving the unit, increasing wire size will accomplish nothing. just IMHO. Voltage drop is just a fact of life, why it bothers people I just dont understand.


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## Speedy Petey (Feb 1, 2004)

jamiedolan said:


> If you really want to get rid of the flicker / dimming, putting the meter / a disconnect really close to the transformer is the answer (then running the necessary size cable, possibly a dedicated cable to the heat pump,,, again that is only if you really care about getting rid of the flicker).
> 
> Running the large cable yourself would be expensive. So unless the light dimming really bothers you, then you mind as well let the power co run it to the garage, then you just have the short run in.


Jamie, I have to agree with Chris. What you are suggesting is no guarantee that there will be no dip or "flicker" in the incoming power or in the house at all.


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## jamiedolan (Sep 2, 2008)

Speedy Petey said:


> Jamie, I have to agree with Chris. What you are suggesting is no guarantee that there will be no dip or "flicker" in the incoming power or in the house at all.


I was of the understanding (perhaps misunderstanding) that the voltage drop that leads to these flickering problems is due to the limitations (resistance) on the service conductors between the transformer and the panel. 

I thought this was due to the service drop cables not being able to handle the draw that is present with the inrush of motor start ups, without having some voltage drop.

I must be confused with something.

Jamie


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## rgsgww (Jul 5, 2008)

The dip/flicker can be related to the transformer, sometimes, regardless of the size of service conductors, you will have dip/flickering. You could put bigger start caps on the motors, that may reduce the amount of dip.


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## Gigs (Oct 26, 2008)

He could try changing to CF lights, they seem to smooth over flickers a little better than incandescents which show you every dipped half wave (if you got the eye for it). Since incandescents are banned for general lighting, taking effect in 2014, he might as well.

I agree it's probably the transformer contributing to a large part of the drop.


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## rgsgww (Jul 5, 2008)

Gigs said:


> He could try changing to CF lights, they seem to smooth over flickers a little better than incandescents which show you every dipped half wave (if you got the eye for it). Since incandescents are banned for general lighting, taking effect in 2014, he might as well.
> 
> I agree it's probably the transformer contributing to a large part of the drop.



CFs sound like a good idea. Yeah, that transformer was probably designed for one 500-600 amp load. Unlike the ones powering several houses.


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## AndrewF (Dec 29, 2008)

That transformer is dedicated to my house alone. I live out in the country, no other houses are on it. Peak draw on the compressor IIRC is about 30 amps at startup.

I am going to check, its possible the gauge of the wire that feeds the heat pump now is not really large enough for the run, and may be contributing to the problem. It is approximately a 80' run from the panel to the heat pump.


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## rgsgww (Jul 5, 2008)

AndrewF said:


> That transformer is dedicated to my house alone. I live out in the country, no other houses are on it. Peak draw on the compressor IIRC is about 30 amps at startup.
> 
> I am going to check, its possible the gauge of the wire that feeds the heat pump now is not really large enough for the run, and may be contributing to the problem. It is approximately a 80' run from the panel to the heat pump.



Might be 10 awg. You could bump it up to 8 if you like, but probably wont make a difference.


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## jamiedolan (Sep 2, 2008)

AndrewF said:


> That transformer is dedicated to my house alone. I live out in the country, no other houses are on it. Peak draw on the compressor IIRC is about 30 amps at startup.


Motors can draw up to around 6 times there name plate rating in inrush current (at startup). 
A plain old 15A miter saw can draw around 90A of inrush.
Jamie


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## AndrewF (Dec 29, 2008)

My clamp on meter registered a peak surge of 134 amps at startup....running amps varies between 13-16 amps.

The cable is 6/2. ....which probably explains the sudden voltage drop for that length of wire and peak draw.

I think I will upgrade that cable and run it off of the 100 amp sub-panel I installed in the basement. I used #2 copper for that panel with a total run of around 60'. That would result in the run from the outdoor unit to the panel around 25'.


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## jamiedolan (Sep 2, 2008)

AndrewF said:


> My clamp on meter registered a peak surge of 134 amps at startup....running amps varies between 13-16 amps.
> 
> The cable is 6/2. ....which probably explains the sudden voltage drop.


What clamp meter do you have? Is it a RMS clamp meter rated to capture inrush current? I've been looking at getting one of the fluke RMS meters with inrush capture so I can see exactly what is happening on start ups of motor loads.

Jamie


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## jamiedolan (Sep 2, 2008)

Andrew, 

You may find this link intresting. 

http://www.mikeholt.com/technical.p...ed/10-7-99&type=u&title=Power Quality Article

At the bottom Mike Holt (very well respected in the industry) makes some comments about the situation such as:

"The light flicker is caused by excessive instantaneous voltage drop when the large high-efficiency scroll compressor started with an instantaneous inrush current of 240 amperes. By installing a hard-start, the flicker duration was shortened, but not removed. When the heat pump was connected to the service, the voltage drop to Panel A was reduced, but the lights in the house still flickered, just not as much."

He also states:

"*I’m not moving the utility transformer closer to my house*, I don’t mind the lights flickering when the heat pump starts, and most importantly my wife doesn’t care at all. She though that’s the way it’s suppose to be (or maybe I told her that)."

If you read that article, along with other stuff on the site Mike Holt has written, I think you will see what I was getting at when I was talking about have your meter / disconnect close to the transformer and having a separate run to very loads like the heat pump that have high inrush draw. 

Jamie


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## jbfan (Jul 1, 2004)

AndrewF said:


> My clamp on meter registered a peak surge of 134 amps at startup....running amps varies between 13-16 amps.
> 
> The cable is 6/2. ....which probably explains the sudden voltage drop for that length of wire and peak draw.
> 
> I think I will upgrade that cable and run it off of the 100 amp sub-panel I installed in the basement. I used #2 copper for that panel with a total run of around 60'. That would result in the run from the outdoor unit to the panel around 25'.


If you have 6/2 feeding the ac unit, you have done all you can do to try to prevent voltage drop.
Anything larger than that most likely will not fit the breaker, and the cost will shock you.

I would use the hard start kit.


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## rgsgww (Jul 5, 2008)

6 awg? Did cerrowire and southwire tell you what size wire to use?


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## AndrewF (Dec 29, 2008)

It was already there and the HVAC guy helping me said it was fine since the run load was only 15 amps. I suspected at the time it might be too small, but the breaker never tripped, so I let it go as I had other pressing projects to address.

I am going to proceed down the path and obtain a hard-start for my unit.


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## jbfan (Jul 1, 2004)

AndrewF said:


> It was already there and the HVAC guy helping me said it was fine since the run load was only 15 amps. I suspected at the time it might be too small, but the breaker never tripped, so I let it go as I had other pressing projects to address.
> 
> I am going to proceed down the path and obtain a hard-start for my unit.


# 6 wire is not too small, it is the other way around. That is a heafty wire to have a 15 amp load on it, not that there is anything wrong with usine the larger wire. You do not need to consider using a larger wire for the ac!


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## chris75 (Aug 25, 2007)

AndrewF said:


> It was already there and the HVAC guy helping me said it was fine since the run load was only 15 amps. I suspected at the time it might be too small, but the breaker never tripped, so I let it go as I had other pressing projects to address.
> 
> I am going to proceed down the path and obtain a hard-start for my unit.


If the unit had a nameplate of MAX. breaker 20 amps, I would have used #14 AWG myself. but thats just crazy talk. :laughing:


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## AndrewF (Dec 29, 2008)

jbfan said:


> # 6 wire is not too small, it is the other way around. That is a heafty wire to have a 15 amp load on it, not that there is anything wrong with usine the larger wire. You do not need to consider using a larger wire for the ac!


Really?

IIRC, the manufacture states it should be connected to a 50 amp disconnect by the HP.


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## chris75 (Aug 25, 2007)

AndrewF said:


> Really?
> 
> IIRC, the manufacture states it should be connected to a 50 amp disconnect by the HP.


Always go by the nameplate, then if you feel voltage drop is a concern then increase the wire size.


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