Two breakers required to de-energize circuit

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The worst is when you find this on a Heavy-Up. You have that 50/50 chance that they end up on opposite phases after the change-out. I've starting explicitly calling this out in contracts that it is required to be correct at T&M if it happens. This has happened to me at least 3 times.

Mark
 
mbrooke said:
That would be at least a few code violations.

You still have two neutrals carrying load, some not in the same NM jacket.

A home wired at 3va per foot needs all the original circuits to remain complaint, if the SABCs, same thing.
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3 VA per square foot is for load calculations. How does this break down into point to point wiring? Other than the minimum number of circuits, it doesn’t. You could theoretically put every recep on one breaker except those requiring dedicated circuits. In fact I’ve found some houses very, very close to this.

I agree with the neutrals argument but only in that current carrying conductors should be the same length. That’s not a Code requirement but an engineering one. Under your rules THHN or MC would not be allowable wire types. I guess all commercial installs are huge Code violations.

It’s a Code violation to share neutrals but that wouldn’t be happening here after removing one breaker. You have one breaker, and possibly 2 neutrals at least from the MDP. Knowing the hits are tied together who knows how the neutrals run.

Often this happens where you have multiple switches or where a light and receptacle run together and the lights are on one circuit and receptacles on another. Somebody feels they are probably all the same circuit and just gets two big wire nuts. If you are in a gang box and don’t pay very close attention when you take it apart or something falls out all you see is black and white wires and sometimes red. Usually the assumption is everything in one box belongs to the same circuit. It’s easier that way.
 
paulengr said:
Often this happens where you have multiple switches or where a light and receptacle run together and the lights are on one circuit and receptacles on another. Somebody feels they are probably all the same circuit and just gets two big wire nuts. If you are in a gang box and don’t pay very close attention when you take it apart or something falls out all you see is black and white wires and sometimes red. Usually the assumption is everything in one box belongs to the same circuit. It’s easier that way.
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This is a very dangerous assumption to make. And one of the biggest reasons why homeowners should not be doing their own electrical work. What if he turns off the breaker for the light in order to replace a defective switch, then doesn't realize that the garbage disposal switch (in the same box) is on a dedicated circuit. He comes into contact with the wires on that switch and gets zapped.
 
paulengr said:
3 VA per square foot is for load calculations. How does this break down into point to point wiring? Other than the minimum number of circuits, it doesn’t. You could theoretically put every recep on one breaker except those requiring dedicated circuits. In fact I’ve found some houses very, very close to this.

I agree with the neutrals argument but only in that current carrying conductors should be the same length. That’s not a Code requirement but an engineering one. Under your rules THHN or MC would not be allowable wire types. I guess all commercial installs are huge Code violations.

It’s a Code violation to share neutrals but that wouldn’t be happening here after removing one breaker. You have one breaker, and possibly 2 neutrals at least from the MDP. Knowing the hits are tied together who knows how the neutrals run.

Often this happens where you have multiple switches or where a light and receptacle run together and the lights are on one circuit and receptacles on another. Somebody feels they are probably all the same circuit and just gets two big wire nuts. If you are in a gang box and don’t pay very close attention when you take it apart or something falls out all you see is black and white wires and sometimes red. Usually the assumption is everything in one box belongs to the same circuit. It’s easier that way.
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See 220.14 J.

Also this:

nec 220-4

www.naffainc.com


2000 square feet x 3 = 6000/120= 50 amps. Such a home would need either 4 15 amp general use circuits or 3 20 amp general use circuits.

Small homes, or very old homes can legally get away with a single circuit.

Length on the neutrals isn't the big hazard, rather that they are not connected together. It is possible to draw more than 15 or 20 amps steady on either side of the neutral demarcation point. The neutral is in violation 240.4 D.

Second is the EGCs. If not tied together, each EGC is essentially protected by 30, 45 or 50 amp OCPD. This is both an increased shock hazard and a possible fire hazard in that the EGC could overheat clearing a fault.

And of course you have anyone working on the circuit or panel thinking its dead when in reality live.
 
jeff48356 said:
This is a very dangerous assumption to make. And one of the biggest reasons why homeowners should not be doing their own electrical work. What if he turns off the breaker for the light in order to replace a defective switch, then doesn't realize that the garbage disposal switch (in the same box) is on a dedicated circuit. He comes into contact with the wires on that switch and gets zapped.
Click to expand...
It would be just as dangerous if an electrician did this.
 
petersonra said:
It would be just as dangerous if an electrician did this.
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True, but an electrician would know that the disposal is on a different circuit, and he would have the knowledge and experience not to assume everything in a box is all one circuit. So it is far less likely that such a situation would happen if an electrician did the work instead.
 
DIY or Professional, one circuit or many, a qualified person knows to check for voltage prior to work.
 
paulengr said:
3 VA per square foot is for load calculations. How does this break down into point to point wiring? Other than the minimum number of circuits, it doesn’t. You could theoretically put every recep on one breaker except those requiring dedicated circuits. In fact I’ve found some houses very, very close to this.

I agree with the neutrals argument but only in that current carrying conductors should be the same length. That’s not a Code requirement but an engineering one. Under your rules THHN or MC would not be allowable wire types. I guess all commercial installs are huge Code violations.

It’s a Code violation to share neutrals but that wouldn’t be happening here after removing one breaker. You have one breaker, and possibly 2 neutrals at least from the MDP. Knowing the hits are tied together who knows how the neutrals run.

Often this happens where you have multiple switches or where a light and receptacle run together and the lights are on one circuit and receptacles on another. Somebody feels they are probably all the same circuit and just gets two big wire nuts. If you are in a gang box and don’t pay very close attention when you take it apart or something falls out all you see is black and white wires and sometimes red. Usually the assumption is everything in one box belongs to the same circuit. It’s easier that way.
Click to expand...

Here is my reference:

 
paulengr said:
3 VA per square foot is for load calculations. How does this break down into point to point wiring? Other than the minimum number of circuits, it doesn’t. You could theoretically put every recep on one breaker except those requiring dedicated circuits.
Click to expand...
This is a complete myth, and I don't know why it gets perpetuated among so many.

We are to calculate load at 3va/sf

Not only that, we are required to have enough circuits to handle that load.

Then going further, we are required go have that load evenly distributed among the circuits.
 

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