What do you do when.......

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wbalsam1

Senior Member
Location
Upper Jay, NY
If the panelboard had mwbc's that were, thru some ill-advised scheme, or inadvertently, placed on the same phase and the neutral return current became additive I could see an increased risk of overheating the neutral conductor which would increase the risk of fire. :smile:
 

wbalsam1

Senior Member
Location
Upper Jay, NY
Pierre C Belarge said:
Does the neutral conductor supplying the service carry the imbalance of the circuits?

You have only to remove that grounded conductor for a brief moment, stand back and watch the phase conductors try to stabilize the voltage and in so doing, creating parallel series circuits, wreaking havoc with 120 nominal loads in the house, to make a believer out of any skeptic. :D The poco's loose lots of money every year to loose H-taps on the pole when the neutral drops and the phases try to sort out the imbalance. :smile:
 

iwire

Moderator
Staff member
Location
Massachusetts
wbalsam1 said:
If the panelboard had mwbc's that were, thru some ill-advised scheme, or inadvertently, placed on the same phase and the neutral return current became additive I could see an increased risk of overheating the neutral conductor which would increase the risk of fire. :smile:


Yes, but it has already been made clear that there are no multi-wire branch circuits in this panel.
 

davedottcom

Senior Member
Hey Bob, Peter never replied to the question of (is there any multi-wire branch circuits)
That question was directed to myself from ChrisKennedy. It was in reference to the 120 volt panels I have installed, to which I replied "Absolutely not"

Sooo, where is Peter anyway?!?

For all we know it's loaded with 240 volt circuits!!!
 

Jim W in Tampa

Senior Member
Location
Tampa Florida
We all did miss something here.OP never did say what exactly was feeding this sub or if it had mwbc.For all we know it could be 10-2 with ground and i have seen it.
 

benaround

Senior Member
Location
Arizona
Peter,

Run a new cable, when it comes to things like this I always think," What

would I do if it was my Mother's house" and the answer comes real easy.
 

peter d

Senior Member
Location
New England
OK, I'm back.

Yes, the panel has a multiwire circuit - yet another 3-wire (no separate ground) feeding another subpanel downstream from it.

The reason for the replacement was to remove an FPE.

I did not resolve any of the grounding/bonding issues. I did not have time to address it. I replaced the panel and put it back the way it was. As I mentioned, adding separate grounds will be a major undertaking that I will address when I have time.
 

peter d

Senior Member
Location
New England
Jim W in Tampa said:
We all did miss something here.OP never did say what exactly was feeding this sub or if it had mwbc.

No, I did not mention the presence of MWBC's, but I did mention the feeder:

peter d said:
and discover that it's only fed with old 3-wire cable without a ground (just 3 insulated conductors)?

I presumed it was obvious that 3 insulated conductors would immediately ring a bell as being exactly like the old 3-wire dryer and range circuits (L1, L2, N)
 

Jim W in Tampa

Senior Member
Location
Tampa Florida
peter d said:
No, I did not mention the presence of MWBC's, but I did mention the feeder:



I presumed it was obvious that 3 insulated conductors would immediately ring a bell as being exactly like the old 3-wire dryer and range circuits (L1, L2, N)

Can we assume this job will not be inspected ? Hope you know that its now your name on that panel.Should they sell the house and buyer hires a sharp HI you will be caught in a messy trap and perhaps be fixing free.I dont think i would have done this.
 

emahler

Senior Member
peter d said:
OK, I'm back.

Yes, the panel has a multiwire circuit - yet another 3-wire (no separate ground) feeding another subpanel downstream from it.

The reason for the replacement was to remove an FPE.

I did not resolve any of the grounding/bonding issues. I did not have time to address it. I replaced the panel and put it back the way it was. As I mentioned, adding separate grounds will be a major undertaking that I will address when I have time.

I have one question....what would you have done if you were employed by someone else? i.e. "let someone else worry about the money part"

I ask, because over my time in this industry, I've noticed distinctive differences in guys thought processes from when they were employees to when they were/are employers.
 

tallguy

Senior Member
georgestolz said:
Pierre, I don't believe 210.11 applies to services or feeders, it's in the wrong article. I don't see a similar requirement for services or feeders. :)
Obviously he can speak for himself, but I thought Pierre's point wasn't that this applies to services and/or feeders, but rather that it applies to the branch circuits so that the services or feeders are not harmed by an imbalance.

For some reason this thought had crossed my mind the other day, but I can't recall what triggered it. At any rate, my question would be this: if you put 110A of unbalanced load on one leg (i.e. 0A on the other leg) of a 200A 240v (single phase) main, would it trip? Or does it need to get to 200A before it trips? If it won't trip until 200A, do you care? Isn't a 200A panel rated for whatever combination of 200A you can throw at it, in the absence of some instruction of the label that says otherwise?
 

davedottcom

Senior Member
Tallguy, A 200 amp breaker should not trip from overcurrent if 200 amps were flowing through just 1 phase or both.
I've never heard of any breaker or panel having a "Minimum" current rating!
 

tallguy

Senior Member
davedottcom said:
Tallguy, A 200 amp breaker should not trip from overcurrent if 200 amps were flowing through just 1 phase or both.
I've never heard of any breaker or panel having a "Minimum" current rating!
I think I understand what he was saying, but I don't grasp Pierre's concern then.
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
As I see it, 210.11(B) is requiring the general lighting and appliance circuits required by the load calculations to serve the entire calculated area evenly. That does not mean that all the 210.52 required receptacles and 210.70 required lighting outlets can't all be on the same phase, IMO.

I believe it is to prevent someone from putting the entire house on one circuit, and then tacking on two or three more circuits covering next to no load or square footage and thus overloading that circuit.

Edit to add - I'm not quite sure where Pierre is coming from either, but it's been too long since we've had an argument. :D
 

peter d

Senior Member
Location
New England
emahler said:
I have one question....what would you have done if you were employed by someone else? i.e. "let someone else worry about the money part"


I know where you're going with this...yeah, it's funny how quickly your perspective can change. :)

In this case money was not an issue, as it was a charity job. The old FPE panel was that way for 50 years - I know, it doesn't make it right, but one thing I've realized that we can't save the world by correcting every violation that we come across.
 

electricmanscott

Senior Member
Location
Boston, MA
peter d said:
In this case money was not an issue, as it was a charity job. The old FPE panel was that way for 50 years - I know, it doesn't make it right, but one thing I've realized that we can't save the world by correcting every violation that we come across.


I know where you are coming from. You help someone out and it turns into a nightmare.

No good deed goes unpunished. :rolleyes:
 
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