# How to Know if you have a 20 amp circuit



## sitkasassy (May 11, 2011)

I am considering buying a commercial grade treadmill that has the following power requirements: 120 Volt/20 Amp Dedicated (NEMA 5-20 Receptacle) 

Is there anyway to quickly check to see if I have any 20 amp dedicated circuits. If I need installation I will call a professional--I just want to know what I have before I bring someone in.

Thanks for the feedback!


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## a7ecorsair (Jun 1, 2010)

sitkasassy said:


> I am considering buying a commercial grade treadmill that has the following power requirements: 120 Volt/20 Amp Dedicated (NEMA 5-20 Receptacle)
> 
> Is there anyway to quickly check to see if I have any 20 amp dedicated circuits. If I need installation I will call a professional--I just want to know what I have before I bring someone in.
> 
> Thanks for the feedback!


Unless there was some special requirement from the past, I doubt if you have a dedicated 20 amp receptacle and in most cases you won't even have 20 amp receptacles. A 120 v 20 amp receptacle will have one slot that looks like a sideways T. If it is a dedicated circuit it would be a single receptacle instead of a duplex.


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## nap (Dec 4, 2007)

to the most basic portion of your question of how do you know if you have a 20 amp circuit:

you look at the breakers in your breaker panel. If there is a "20" on the handle, it's a 20 amp circuit.

as to one being dedicated; almost guaranteed you do not have a dedicated 20 amp circuit. A dedicated circuit of any amperage rating would typically only be installed if needed. Unless the previous owner of the house just happened to need a dedicated 20 amp circuit in the same area you need one, there is not going to be one available for your use.


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## michaelcherr (Nov 10, 2010)

You probably don't have a dedicated circuit.
I make an electrcal map of every house I buy.
I get a friend with a tester in every plug, and flip breakers till it goes off.
If I blow a fuse, I look at my labels, or blueprint, and I instantly toggle the correct one.

Doing this exercise will let you know if any circuit is dedicated.
Other than refrigerator or specialty appliances like a welder, big tablesaw, treadmill, or window a/c, you don't have a dedicated circuit.

The cheap way to get a dedicated circuit is to find a 20amp circuit with nothing but a couple outlets on it and simply don't use the other outlets when you use the treadmill.


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## sirsparksalot (Oct 16, 2010)

a7ecorsair said:


> If it is a dedicated circuit it would be a single receptacle instead of a duplex.


Unless a handyman did the wiring, in which case it could be a duplex :wink:


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## SD515 (Aug 17, 2008)

sirsparksalot said:


> Unless a handyman did the wiring, in which case it could be a duplex :wink:


Then technically it wouldn't be a dedicated circuit.


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## brric (Mar 5, 2010)

a7ecorsair said:


> Unless there was some special requirement from the past, I doubt if you have a dedicated 20 amp receptacle and in most cases you won't even have 20 amp receptacles. A 120 v 20 amp receptacle will have one slot that looks like a sideways T. If it is a dedicated circuit it would be a single receptacle instead of a duplex.


Sorry, we install dedicated circuits all the time with duplex receptacles. For instance, refrigerators.


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## sirsparksalot (Oct 16, 2010)

brric said:


> Sorry, we install dedicated circuits all the time with duplex receptacles. For instance, refrigerators.


Then, unless the Duplex was split, this wouldn't count as a dedicated circuit, as defined by NEC 100:




> *Branch Circuit, Individual. *
> ​​​​A branch circuit that supplies only one utilization equipment.​


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## brric (Mar 5, 2010)

sirsparksalot said:


> Then, unless the Duplex was split, this wouldn't count as a dedicated circuit, as defined by NEC 100:


 How is a duplex receptacle, behind a refrigerator, suppling more than one utilization device?


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## secutanudu (Mar 15, 2009)

sitkasassy said:


> Is there anyway to quickly check to see if I have any 20 amp dedicated circuits.


I don't think you understand what a "dedicated circuit" is. All it means is that you have a breaker in your panel that ONLY controls one thing, in this case an outlet that your treadmill will plug into. Since the previous owner did not likely have a high-powered electrical device that required a 20A *dedicated* circuit, the chances of you having one that is available for use is very low.


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## joed (Mar 13, 2005)

A NEMA 5-20r has one slot that is sideways. If you don't have any receptacles like that then you don't have the circuit you need.


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## sirsparksalot (Oct 16, 2010)

brric said:


> How is a duplex receptacle, behind a refrigerator, suppling more than one utilization device?


You must know that the possibility exists for the duplex to be used to plug in a microwave, or anything else that the unlearned may desire.

A dedicated circuit, to me, is one which has a single receptacle.


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## brric (Mar 5, 2010)

sirsparksalot said:


> You must know that the possibility exists for the duplex to be used to plug in a microwave, or anything else that the unlearned may desire.
> 
> A dedicated circuit, to me, is one which has a single receptacle.


I believe your interpretation is wrong, but I understand your thinking.


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## The Deez (Jul 9, 2010)

sirsparksalot said:


> Unless a handyman did the wiring, in which case it could be a duplex :wink:


This isn't true, we install duplex recepticals on dedicated circuits all the time. Just because it's a duplex or a quad even doesn't mean it isn't a dedicated circuit.


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## nap (Dec 4, 2007)

does anybody have the NEC on their computer?

If so, please look for anything referring to a "dedicated circuit"


To my interpretation of the term and lacking any direction from the code otherwise, a dedicated circuit is one that is established for a specific use. I often suggest people provide a dedicated circuit to certain areas of a home such as where they will place an entertainment center. I suggest a double duplex or even 2 double duplexes be installed on that dedicated circuit. I know that every time I have installed a dedicated circuit for a fire alarm panel or the phone companies equipment, not only did they not care if there was more than a simplex recep, in the case of the phone company, they require either a duplex or even a double duplex.


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## Leah Frances (Jan 13, 2008)

Manufacturers love to require 'dedicated circuits'. *The NEC does not use the term.* The NEC talks about "Individual branch circuits" defined as "a branch circuit that supplies only one utilization equipment." In english: A circuit with ONLY ONE appliance plugged into it...ever. 

Some inspectors will require that individual branch circuits run to refrigerators have only a single receptacle. This is not specified in the NEC.

The NEC 210.21(B)(1) requires that *IF a single rec* is used then is must be rated not less than the individual branch circuit rating. 

So, with ONE rec on a 15Amp circuit you MUST use a 15 Amp rec. 
with ONE rec on a 20Amp circuit you MUST use a 20 Amp rec.

Putting a duplex rec on an 'Individual Branch circuit' does not invalidate it as an 'Individual Branch Circuit". Plugging more than one thing into that duplex rec does.


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## Leah Frances (Jan 13, 2008)

In my opinion: Manufacturers require so-called 'dedicated circuits' to limit their potential liability when people improperly use high-draw items. Also, in theory, to potentially limit their warranty coverage (BTW, I've never had that problem).... "Oh, your treadmill broke? Did you have it on a 'dedicated circuit'? No. Then we won't warranty it"


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## nap (Dec 4, 2007)

Leah Frances said:


> Manufacturers love to require 'dedicated circuits'. *The NEC does not use the term.* The NEC talks about "Individual branch circuits" defined as "a branch circuit that supplies only one utilization equipment." In english: A circuit with ONLY ONE appliance plugged into it...ever.
> 
> Some inspectors will require that individual branch circuits run to refrigerators have only a single receptacle. This is not specified in the NEC.
> 
> ...


all right. Have you been studying or did you snark that from somewhere else.


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## linuxrunner (Oct 18, 2010)

I am going to have to agree with Leah, the biggest reason for the "dedicated circuit" requirement is to rule out interference to or from other equipment on the same circuit. I would doubt it is necessary to have a dedicated circuit for a treadmill. Just don't plug in other sensitive or power hungry equipment into the same circuit.

That being said your best bet for a dedicated 20amp circuit would be a window A/C unit. You are looking for a plug with a t shape on one side, probably just under a window. Which works out good because who doesn't want to workout in front of a window? :thumbsup:


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## kbsparky (Sep 11, 2008)

Leah Frances said:


> ...
> The NEC 210.21(B)(1) requires that *IF a single rec* is used then is must be rated not less than the individual branch circuit rating.
> 
> So, with ONE rec on a 15Amp circuit you MUST use a 15 Amp rec.
> ...


Section 210.21(B)(1) allows a 20 Amp single receptacle on a 15 Amp circuit. 

20 Amp outlet is not less than 15 Amp circuit ... :whistling2:

This is the same section that allows a single 50 Amp outlet (range) on a 40 Amp circuit.


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## Leah Frances (Jan 13, 2008)

nap said:


> all right. Have you been studying or did you snark that from somewhere else.


I've been studying. Mullin's Electrical 2008 NEC edition.


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## nap (Dec 4, 2007)

Leah Frances said:


> I've been studying. Mullin's Electrical 2008 NEC edition.


ya did good except the thing kpsparky caught. If you re-read the section, you will realize why:




> The NEC 210.21(B)(1) requires that IF a single rec is used then is must be rated not less than the individual branch circuit rating.


that states the recep cannot be rated for less than the circuit. They are concerned that you do not overload the recep. The circuit will take care of itself and trip if overloaded. The recep will heat up and...

well, we don't want to go there.


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## Leah Frances (Jan 13, 2008)

kbsparky said:


> Section 210.21(B)(1) allows a 20 Amp single receptacle on a 15 Amp circuit.
> 
> 20 Amp outlet is not less than 15 Amp circuit ... :whistling2:
> 
> This is the same section that allows a single 50 Amp outlet (range) on a 40 Amp circuit.


NOPE. That is TABLE 210.21(B)(3). :whistling2:

Allows 40 or 50 Amp rec on a 40 amp circuit.


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## Leah Frances (Jan 13, 2008)

nap said:


> ya did good except the thing kpsparky caught. If you re-read the section, you will realize why:


Thanks for the complement and I still think I've got Sparky on the 40 or 50 Amp recs on 40 Amp circuits. As per the table.


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## kbsparky (Sep 11, 2008)

Leah Frances said:


> NOPE. That is TABLE 210.21(B)(3). :whistling2:
> 
> Allows 40 or 50 Amp rec on a 40 amp circuit.
> 
> Thanks for the complement and I still think I've got Sparky on the 40 or 50 Amp recs on 40 Amp circuits. As per the table.


Look again, Leah. Table 210.21(B)(3) is for circuits that have two or more receptacles. I stand by my original post. :yes:


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## Leah Frances (Jan 13, 2008)

kbsparky said:


> Look again, Leah. Table 210.21(B)(3) is for circuits that have two or more receptacles. I stand by my original post. :yes:


YEah, so I'm looking at that.

I'll get back at'cha. I'm not sure I'm right, right. Because, I'm no pro. Just trying to learn. :thumbsup:


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## kbsparky (Sep 11, 2008)

Leah, to maintain our electrical licenses, we are required to have 5 hours of continuing education per year. One of the things that was discussed in detail at one of those courses was this very topic.

Maybe you'd like to attend one such course with us sometime? You'd be surprised at what you might learn .... (of course, they ain't cheap) :wink:


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## Leah Frances (Jan 13, 2008)

kbsparky said:


> Leah, to maintain our electrical licenses, we are required to have 5 hours of continuing education per year. One of the things that was discussed in detail at one of those courses was this very topic.
> 
> Maybe you'd like to attend one such course with us sometime? You'd be surprised at what you might learn .... (of course, they ain't cheap) :wink:


Ah, education for education's sake. Sounds awesome. So this is REALLY bugging me and I've got to wrap my mind around it. I totally acknowledge that I both 
a) lack the education and experience to be a pro; and
b) am smart enough to admit it :wink:

In what situations would you put a SINGLE 40 or 50 rec on a 40amp circuit? what section of the code controls this?

Just had a tiny bit of a family emergency, but I'm not dropping out because I'm not interested. Just busy.


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## kbsparky (Sep 11, 2008)

Leah Frances said:


> ...In what situations would you put a SINGLE 40 or 50 rec on a 40amp circuit? ....


I already mentioned this: An electric RANGE. Many of them use a 50 Amp NEMA14-50 receptacle, wired with #8/3 romex, on a 40 Amp breaker. :thumbup:

FWIW, I've never seen any receptacle rated at 40 Amps. The NEMA configuration chart goes from 30 to 50.


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## nap (Dec 4, 2007)

kbsparky said:


> Leah, to maintain our electrical licenses, we are required to have 5 hours of continuing education per year. One of the things that was discussed in detail at one of those courses was this very topic.
> 
> Maybe you'd like to attend one such course with us sometime? You'd be surprised at what you might learn .... (of course, they ain't cheap) :wink:


what do ya mean they aren't cheap? Mine are free!! but I only have to take one each time Michigan accepts a new code cycle.


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## a7ecorsair (Jun 1, 2010)

You all realize that we have a two page thread that has covered this topic quite well. I wonder what the OP will think when he/she logs back in to check on an answer to the original question



sitkasassy said:


> I am considering buying a commercial grade treadmill that has the following power requirements: 120 Volt/20 Amp Dedicated (NEMA 5-20 Receptacle)


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## kbsparky (Sep 11, 2008)

nap said:


> what do ya mean they aren't cheap? Mine are free!! but I only have to take one each time Michigan accepts a new code cycle.


I get flyers in the mail all the time for courses that cost several hundred dollars for 5 hours of CE credits. I throw those into the "circular file"

Inspection agencies around here routinely offer 5 hour courses for $75-100 each. Occasionally, a local supply house or trade association will "sponsor" a code class for a reduced rate -- I took one recently for $54. A bargain by any standards, but beyond what most DIY's are willing to pay.

As for yours being "free" I highly doubt that -- it's probably included in the price of your license renewal fees.


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## nap (Dec 4, 2007)

kbsparky said:


> As for yours being "free" I highly doubt that -- it's probably included in the price of your license renewal fees.


Nope. Union puts it on. No charge:clap::clap:


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## kbsparky (Sep 11, 2008)

Well, then it's _UNION DUES _that pays for it! 

TANSTAAFL!!


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