Are uninsulated neutrals ...

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DannyG

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Location
Bucks , PA
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electrician
...allowed in correctly fed (floating neutral/separated grounds) subpanels?


Hello all,

Would someone be kind enough to point me to the NEC article that prohibits uninsulated neutrals in sub panels?

I got flagged in NJ for not insulating the stranded aluminum neutral on an existing older 40 amp 240 volt stove circuit when converting one of 2 main panels to a subpanel. (to accommodate a portable generator circuit)

Backstory: This is the first I've heard of this "no uninsulated neutrals in subpanels" thing. It's also the first time I've seen 2 main panels fed from one bolt on meter. I'm used to pulling the meter when doing service work. Just like me, firemen can't just pull a bolt on meter either. Which I thought was insane. A utility truck has to be dispatched to kill the pole mounted transformer first. Then unbolt the meter. If you can get close enough because THE HOUSE IS ON FIRE! It sounds terrible even on paper.

It was a big song and dance to get a utility disconnect/reconnect on the same day. Mainly because they would not reconnect without an inspection by the township I was working in, on the same day. At first the utility gave me a 5 hour window to do an eleven hour job. I had to fight them. I could not do the job and have it inspected in 5 hours ha ha. It was my first job in a new utility area and they just do it different there. Thanks for listening

Stay safe

L.
 
Look at 250.140 exception, then in particular, part #3
3) The grounded conductor is insulated, or the grounded conductor
is uninsulated and part of a Type SE service-entrance cable and
the branch circuit originates at the service equipment.
Click to expand...

The exception allows existing circuits that have no grounding conductor (EGC), to use the neutral as the grounding (EGC) conductor for stoves/ranges and dryers. These were normally wired with SE cable that had a bare neutral. These circuits would have to originate in the main service panel.

Since you converted the existing main panel to a subpanel, the exception no longer applies. Now most inspectors in my area will allow us to use white tape to cover the bare neutral, especially if pulling a new 4-wire would cause extensive damage to the dwelling. They don't have to do this, but they use a little common sense.
The reason the bare neutral isn't allowed in a subpanel feeding a stove or dryer is, it is also acting as the ground (EGC) and will have current on it. Should it come in contact anywhere along the way with any conductive surface, there is a shock hazard.
 
Last edited:
DannyG said:
...allowed in correctly fed (floating neutral/separated grounds) subpanels?


Hello all,

Would someone be kind enough to point me to the NEC article that prohibits uninsulated neutrals in sub panels?

I got flagged in NJ for not insulating the stranded aluminum neutral on an existing older 40 amp 240 volt stove circuit when converting one of 2 main panels to a subpanel. (to accommodate a portable generator circuit)

Backstory: This is the first I've heard of this "no uninsulated neutrals in subpanels" thing. It's also the first time I've seen 2 main panels fed from one bolt on meter. I'm used to pulling the meter when doing service work. Just like me, firemen can't just pull a bolt on meter either. Which I thought was insane. A utility truck has to be dispatched to kill the pole mounted transformer first. Then unbolt the meter. If you can get close enough because THE HOUSE IS ON FIRE! It sounds terrible even on paper.

It was a big song and dance to get a utility disconnect/reconnect on the same day. Mainly because they would not reconnect without an inspection by the township I was working in, on the same day. At first the utility gave me a 5 hour window to do an eleven hour job. I had to fight them. I could not do the job and have it inspected in 5 hours ha ha. It was my first job in a new utility area and they just do it different there. Thanks for listening

Stay safe

L.
Click to expand...

Know the difference between a grounded conductor and a grounding conductor. Think about it. The neutral and grounding (bonding) are two separate circuits. The grounding circuit is not supposed to normally carry any current except in a fault while the grounded circuit always does. So if you intermix them you have current flowing through your metal enclosures. In the extreme case you could have a “one wire” distribution system, using grounding rods as the return path. It might not happen with NM and PVC but it can/should happen with EMT and IMC. This is not as far fetched as it seems. This is how Edison did it before the Edison (GE) “safety system” with 240/120 V grounded neutral came out.

NEC says the grounded conductors are grounded at only one point at the system jumper in the main panel. In the main panel they are all together so it doesn’t matter what a grounded or grounding conductor is in reality (exception: GFCIs and AFCIs). But as soon as you turn a main into a sub panel you need to maintain that distinction. In the sub panel grounded and grounding conductors are on separate bus bars with an insulated and uninsulated one. Hence why you need to use different bus bars. They must be the proper colors and insulated grounded conductors. No more mix and match. More than just adding extensions to wiring and getting creative with drywall grounded conductors are the biggest pain in converting old mains and the reason most electricians would rather leave the main as a main or turn it into a junction box.

Just do it to Code and you’ll have a lot fewer problems with both inspectors and return calls.
 
If this is from meter to panel and there is no main at the meter, it is still service conductors and the neutral doesn't need to be insulated. There could be two (to six) panels (with main breakers) and that is allowed if grouped in one location.

Once you are past the service disconnect you can't use non covered conductor for the grounded conductor (neutral in most cases) other than a few exceptions mostly regarding electric ranges and dryers and existing circuits that were once compliant with that sort of wiring method.
 
Thanks a lot fellas. Now I get it.

He won't let me use electrical tape for insulating. He told me "it's not insulation".

He's OK with heat shrink though.

So that's what I'll do
 
We've had a few threads on this, I most recently ran into this but the circuit hit a jbox and split to a cooktop and oven. The new appliances were still shrink wrapped in the garage and I noticed that both nameplates said '240' as opposed to '120/240' . So the bare ends up just an EGC.
YMMV
 
tortuga said:
We've had a few threads on this, I most recently ran into this but the circuit hit a jbox and split to a cooktop and oven. The new appliances were still shrink wrapped in the garage and I noticed that both nameplates said '240' as opposed to '120/240' . So the bare ends up just an EGC.
Click to expand...
Just remember to make sure the other end is connected to a grounding terminal (if separate).
 
kwired said:
If this is from meter to panel and there is no main at the meter, it is still service conductors and the neutral doesn't need to be insulated. There could be two (to six) panels (with main breakers) and that is allowed if grouped in one location.

Once you are past the service disconnect you can't use non covered conductor for the grounded conductor (neutral in most cases) other than a few exceptions mostly regarding electric ranges and dryers and existing circuits that were once compliant with that sort of wiring method.
Click to expand...
The whole reason for this job is so she can have a generator inlet box. I couldn't figure out how to run 2 main panels on one generator. So my solution was to make only one main panel with a subpanel so her one generator could run all the essential loads wherever they were in the house. I like those breaker lockout things instead of a transfer switch, much easier install with superior results IMO. Obviously everything can't be run at once but I like them way better than a TX switch with limited circuits
 
DannyG said:
The whole reason for this job is so she can have a generator inlet box. I couldn't figure out how to run 2 main panels on one generator. So my solution was to make only one main panel with a subpanel so her one generator could run all the essential loads wherever they were in the house. I like those breaker lockout things instead of a transfer switch, much easier install with superior results IMO. Obviously everything can't be run at once but I like them way better than a TX switch with limited circuits
Click to expand...
For manual transferring, put a breaker interlock in both panels, split the generator feed to supply both panels.
 
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