Any electricians out there?? 120/240 Circuits Question

[Waukesha]

This is a non-generator related question.

I have a Square D QO load center. I'm in the process of adding a sub panel. Sub panel will be mounted ~3ft from the main panel. I'm aware that I need to remove the bonding screw in the sub to keep neutral/ground separate. I'll be running 4 gauge copper L1/L2/N and 10 gauge solid ground., feeding it with a 60A branch circuit from the main panel.

My main load center states that it can accommodate a MAXIMUM of 40 circuits. I'd like to add two tandem circuits in the main panel to create room for the sub panel.

QUESTION: Does a 240v circuit count as 1 circuit or two??? (in the context of the panel 40 circuit max)

Question 2: I've got my panel set up to properly back feed a 240v branch circuit. Does that count towards my 40 circuit limit??

Alternatively I know that I can extend to light/plug circuits and run those out of the sub panel. I believe there is an NEC rule that requires that any runs over 4' require an AFCI, which is no big deal other than I'm trying to keep costs down...

I can't find the exact model # of the panel on any labels on the inside. I believe this is the panel: https://www.royalwholesaleelectric....rcuits-200a-convertible-main-breaker-nema1-ul

 

[wheelspinner]

That means it has 40 places. So a 240 double pole would take 2 spaces. A piggy back breaker with 2 circuits uses one space. Hope that helps

 

[tobyS]

I worked in engineering at Sq D Peru in 74 and know their line well. I'm bonded electrician.

Take a couple photos of the present open panel.

Wheelspinner is right, the 2 pole branch circuit will take 2 spaces.

Breakers to 150 are available at low cost.

Why are all of your spaces full? Do you have everything on individual breakers?

Wheelspinner said the difference of tandem, are two same pole breakers that take one space. Thus 10 spaces can have 20 circuits, all individually protected.

 

[Waukesha]

That means it has 40 places. So a 240 double pole would take 2 spaces. A piggy back breaker with 2 circuits uses one space. Hope that helps

Thanks, Wheelspinner. Mayber I'm over thinking it. I believe that a tandem breaker = 2 circuits. Single (normal) breaker = 1 circuit. I want to say that 240v circuit = 1 circuit (although it takes up two "slots").

 

[Waukesha]

I worked in engineering at Sq D Peru in 74 and know their line well. I'm bonded electrician.

Take a couple photos of the present open panel.

Appreciate your help!

 

[DieselAddict]

This article may help understand where the NEC shifted the burden from thier code to the manufacturers.

What is the maximum number of circuit breakers allowed in an electric panel?

www.howtolookatahouse.com

You'll need to find the ratings for that specific load center to make sure you are within the spec. Panels are generally rated for the number of spaces they have available AND the number of circuits. In many panels those are the same number but in others they are not.

Here is an article explaining what I'm talking about - http://www.ncwhomeinspections.com/42+Circuit+Rule

The backfeed breaker will count towards the circuit limit.

 

[tobyS]

Are these all labeled? Make a list of the left and right side ampere ratings and note the 2 pole or gfi or standard.

 

[tobyS]

Do you have an amp meter to check the balance of use on poles?

 

[Waukesha]

Do you have an amp meter to check the balance of use on poles?

I do, but haven't checked at the panel. I ran for a few days off the MEP-803A during the Texas winter storm in February and I was well balanced then. All circuits were on at that point in time, and nothing has been added since.

 

[Waukesha]

Are these all labeled? Make a list of the left and right side ampere ratings and note the 2 pole or gfi or standard.

Yes, that is with the cover off (which has the labels). I didn't wire the panel, an electrician did.

There are:
8 x 240v branch circuits
1 x 240v generator back feed (in the correct location)
22 x single circuit single space breakers

Total = 40 circuits / 40 spaces.

 

[Waukesha]

This article may help understand where the NEC shifted the burden from thier code to the manufacturers.

What is the maximum number of circuit breakers allowed in an electric panel?

www.howtolookatahouse.com

You'll need to find the ratings for that specific load center to make sure you are within the spec. Panels are generally rated for the number of spaces they have available AND the number of circuits. In many panels those are the same number but in others they are not.

Here is an article explaining what I'm talking about - http://www.ncwhomeinspections.com/42+Circuit+Rule

The backfeed breaker will count towards the circuit limit.

Thanks, DiselAddict. Based on this article you posed (http://www.ncwhomeinspections.com/42+Circuit+Rule), it says " For example you could have a 240v circuit, that is just one circuit but has two pole positions." that leads me to believe that 240v = 1 circuit (out of my 40 max) Do you interpret it that same?

 

[DieselAddict]

Yea, I interpret it the same. Two poles but one circuit.

 

[tobyS]

I can tell you what I would do, but I can't give you advise to change things in there without an electrician.

Sorry

 

[tobyS]

I would find 4 of the standard single pole on the right under the gfi and replace with 2 tandems, after checking to verify one of them is not heavily loaded, replace in 2 spaces and then put the branch in the 2 left. I'm not suggesting a non electrician get into your panel however.

 

[Waukesha]

I would find 4 of the standard single pole on the right under the gfi and replace with 2 tandems, after checking to verify one of them is not heavily loaded, replace in 2 spaces and then put the branch in the 2 left. I'm not suggesting a non electrician get into your panel however.

Thanks, Toby. Understood that everything is an opinion and that non-electricians shouldn't do work in the panel. I'm going to pull the cover and the lower breakers at lunch and see if I can even fit the CTL tandem breakers in there. If I cannot, I WON'T modify them to fit and I'll just bite the bullet and move two circuits to the sub panel where I'll have to use arc faults due to lengthening the wires to the subpanel.

 

[tobyS]

Are you referring to a Ground Fault Interrupter as "arc fault" "due to lengthening the wires to the sub Panel" ?

A ground fault breaker is sensitive to prevent your electrocution in case of you connecting the circuit, including ground. They are required in baths and kitchens......appears the contractor liked them a lot.

The branch is a straight 2 pole, no arc fault.

If you are referring to removing a gfi breaker, yes, use it again in the subpanel.

 

[Scoobyshep]

Are you referring to a Ground Fault Interrupter as "arc fault" "due to lengthening the wires to the sub Panel" ?

A ground fault breaker is sensitive to prevent your electrocution in case of you connecting the circuit, including ground. They are required in baths and kitchens......appears the contractor liked them a lot.

The branch is a straight 2 pole, no arc fault.

If you are referring to removing a gfi breaker, yes, use it again in the subpanel.

Keep in mind these could be combination AFCI GFCI breakers. while GFCI is required in wet locations AFCI is required in bedrooms and some AHJs require them on every 120v circuit

 

[Waukesha]

Keep in mind these could be combination AFCI GFCI breakers. while GFCI is required in wet locations AFCI is required in bedrooms and some AHJs require them on every 120v circuit

Correct. I live in TX where they've recently adopted NEC 2020 which uses ARC Fault circuits on virtually every indoor 120v circuit... Which is annoying since they're about $50/ea vs $20 for the Square D QO series.. Oh well.. Pay to play so that your wife can visually tell which breaker is tripped...

 

[Bill Nutting]

Is this panel on the outside of the house? Don’t think I have ever seen that before.

 

[Scoobyshep]

Correct. I live in TX where they've recently adopted NEC 2020 which uses ARC Fault circuits on virtually every indoor 120v circuit... Which is annoying since they're about $50/ea vs $20 for the Square D QO series.. Oh well.. Pay to play so that your wife can visually tell which breaker is tripped...

I have a distinct hatred for AFCI. They tend to be more of a nuisance than anything else. But ya gotta pass the inspection. Luckily my place was built in 71 so no AFCI.

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