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

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peter d

Senior Member
Location
New England
you go to replace an old subpanel, and discover that it's only fed with old 3-wire cable without a ground (just 3 insulated conductors)?

Is it required to bring it up to the current NEC?

Bringing a separate ground wire to it would be a nightmare, but not impossible.
 

wbalsam1

Senior Member
Location
Upper Jay, NY
It probably wasn't code-compliant when it was first installed, but now's the time to do the job right. Replace with the proper cable would be my vote. :smile:
 

emahler

Senior Member
celtic said:
I don't think the 3-wire would pass even NJ's lax "Rehab Code".

if it was legal at 1 time, and there has been a CO inspection at that location at one time...then it passes the "Rehab Code"....no lie...it's that relaxed
 

davedottcom

Senior Member
If there are no 240 volt circuits and the total load isn't a problem... I would make it a 120 volt panel.
I've done this on many different occasions. Some were existing situations and some were new sub panels that simply didn't need 240 volts.
Time is money, but so is copper!
 

gndrod

Senior Member
Location
Ca and Wa
davedottcom said:
If there are no 240 volt circuits and the total load isn't a problem... I would make it a 120 volt panel.
I've done this on many different occasions. Some were existing situations and some were new sub panels that simply didn't need 240 volts.
Time is money, but so is copper!

Very ingenious. So to balance the main, an equal of single poles will be put on the opposite phase leg from that of the Subs leg? Just curious. rbj
 

M. D.

Senior Member
emahler said:
if it was legal at 1 time, and there has been a CO inspection at that location at one time...then it passes the "Rehab Code"....no lie...it's that relaxed

I don't think it was ever allowed .

I like the Idea of making it a straight 120v panel with a grounding conductor.
 

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
davedottcom said:
If there are no 240 volt circuits and the total load isn't a problem... I would make it a 120 volt panel.
I've done this on many different occasions. Some were existing situations and some were new sub panels that simply didn't need 240 volts.
Time is money, but so is copper!

There were no MWBC's in these subs?
 
Reconfiguring the panel to all 120v circuits may be a good idea. The real issue of concern for this change would be the balancing of phases back at the service. Depending on the load of the circuits in the subpanel, the reconfiguration to a 120v panel may create a fire hazard at the service panel.

There are many variables that only the OP can see at the site that will help to determine what is the ultimate solution to this installation.

If I had to make a determination from the seat of my pants here, I would say install a new feeder, make the determination if they may want an increase in the size of the subpanel while you are at it and then have at it.
 

davedottcom

Senior Member
Ahhh, balance-Shmalance! (just kidding!)
120 circuits are never balanced... except maybe by accident when someone runs the toaster oven on phase A at the same time as they use the microwave on phase b!

"Attempting" to balance 120volt loads is important of course but, is an unbalanced main panel a violation?

Pierre, why would the panel become a fire hazzard if no codes were violated?
 

Jim W in Tampa

Senior Member
Location
Tampa Florida
I see no fire hazard from being unballanced.Try to put a equal load on the other panels other leg.No other cheap fixes.If customer cant afford new wire that is there problem.Your hired to do it legal and safe.Give them the options and point out advantages and disadvantages.I too rather dought it was ever legal.That being the case i would not simply ignore the violation.
 

growler

Senior Member
Location
Atlanta,GA
peter d said:
you go to replace an old subpanel, and discover that it's only fed with old 3-wire cable without a ground (just 3 insulated conductors)?

Is it required to bring it up to the current NEC?


Why are you replacing the sub panel in the first place? The reason I asked is that around here if you are in the middle of a remodeling project they would probably want that feeder replaced. On the other hand if this was considered a repair and no new construction then the feeder could stay.

Only your local AHJ knows for sure.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I sell them on a new feeder. That old one has met it's useful lifespan and it's time to change it. They should be happy that they got away with a non-compliant installation for so long.
 
210.11(B) Loads Evenly Proportioned Among Branch Circuits.



As I mentioned in my earlier post, there is a possibility of a fire if the loads between A-phase and B-phase are disproportionate enough.
In the example for this thread, one may decide to take an entire subpanel and take one of the phases of that panel and make all of the circuits the same phase.
That phase shift could be enough to overload the neutral (mathematically speaking) and create enough heat to start a fire in the neutral connection (especially if the neutral was downsized during the original installation. That location could be in the service panel, meterpan or at the weatherhead. In my experience, I have seen it happen at the weatherhead.
 

davedottcom

Senior Member
210.11 Branch Circuits Required
(B) Load Evenly Proportioned Among Branch Circuits Where the load is calculated on the basis of volt-amperes per square meter or per square foot, the wiring system up to and including the branch-circuit panelboard(s) shall be provided to serve not less than the calculated load. This load shall be evenly proportioned among multioutlet branch circuits within the panelboard(s). Branch-circuit overcurrent devices and circuits shall only be required to be installed to serve the connected load.

So only the circuits that are "calculated on the basis of volt-amperes per square meter or per square foot" need to be balanced? how odd!?

Pierre, I understand your concern completely and I admit I never read 210.11(B) before although I do attempt to balance loads when possible.

But, when converting a 240 panel to 120 you don't need to worry about the "new" neutral wire being smaller because it was originally sized the same as the other ungrounded conductor. At least I would hope it was!
I have never seen a situation where an unbalanced panel caused any hazzard. I guess I always assumed as long as the correct gauges of wire & OC were used, it's not a problem.
I'm very curious, Just how unbalanced were these situations you have seen?
 

iwire

Moderator
Staff member
Location
Massachusetts
Pierre C Belarge said:
As I mentioned in my earlier post, there is a possibility of a fire if the loads between A-phase and B-phase are disproportionate enough.

Pierre I do not understand why you feel there is more of a hazard.

The conductors and equipment are either properly sized or not.

The balance or lack of it does not change the fire hazard.
 
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