electrical panel isolating grounds / neutrals

[nortonden]

I added a new main primary panel and it now feeds a smaller "sub panel" which has co mingled grounds and neutrals. Separating them on to respective busses will be difficult as the wire lengths will be short in some cases. I read the threads on butt crimps vs wire nuts. Considering installing a second ground buss and a second neutral buss to help seperate and land the short wires rather than splicing them. Will use a heavy guage wire to connect the new busses to their respective originals and make sure the neutral busses are isolated from the panel and the ground busses.



Some have sugested that since I have a breaker in the main panel feeding the "sub panel" as well as a breaker receiving the power in the sub that isolating grounds and neutrals in the sub is not necessary.

What say you ?

[Jerry Peck - Codeman]

What say you ?

First, let's start by calling things what they are, and you will only find "sub panels" in submarines - in houses there is "service equipment" where the first main service disconnect is located, then there are "panels" ("panels" include all panels, and service equipment is also a panel, so the difference is whether the panel is, or is not, "service equipment").

So, if I understand what you did, you ADDED "service equipment" and what is now the "panel" WAS originally "service equipment". This would explain why the neutrals and grounds are interconnected in that panel.

The problem becomes that some "service equipment" panels are ONLY listed as 'For Use as Service Equipment ONLY' - this is because they have no provision in them to isolate the neutral from ground. For those panels, there is no way to make them 'not be' "service equipment" - you would need to remove that panel and replace it with a panel which is listed as 'Suitable For Use as Service Equipment" (which allows for isolating the neutrals from ground when not used as service equipment) or a panel which is simply not listed for use as service equipment, i.e., a regular panel.

From your description I cannot tell what you have for the original panel - you will need to read the label on the original panel and see what it is listed and approved for use as.

Isolating the ground in the not-service-equipment-panel IS ABSOLUTELY NECESSARY!

Another problem comes into play here: The original panel was "service equipment" and was fed with "service entrance conductors", which most likely did not have a separate insulated neutral and a separate equipment grounding conductor as service entrance conductors are not required to have an insulated neutral ... but the use of that panel as you are now using it means that the conductors feeding that panel are now "feeders" and the neutral is required to be insulated and there needs to be a separate equipment ground to that panel.

Did you replace the conductors going to the original service equipment with 4 conductors (two 'hots', one 'neutral', and one 'equipment ground')?

Not enough information to answer your question any better than the above at this time.

Check the following things:
- 1) What does the label on the original panel say it is listed for use as? A) 'Service Equipment Only' or B) 'Suitable for Use As Service Equipment', or C) - and it should not be this as it WAS being used as service equipment - not listed for either.
- 2) How many conductors are feeding the original service equipment panel which is now just a regular panel?
- 3) Is the neutral conductor in those conductors in 2) "insulated" (not just 'covered') with properly marked insulation?

[nortonden]

Thanks for your quick response

Replying concisely and in your format for simplicity and accuracy

1) B marked “suitable for use as Service Equipment “

2) 4 insulated conductors feeding regular panel

3) Neutral conductor in 2) has properly marked insulation

Further info

125 amp main breaker at this (former service equipment) now panel receiving hots from 125 amp breaker in new service equipment.

Further questions

If you clear me to isolate grounds and neutrals to get the panel safe and correct, I’m considering adding an additional “floating “ (sic) neutral bar wired to original neutral bar and an additional ground bar wired to original ground bar to facilitate picking up the shorter grounds and neutrals and avoid the butt splice wire nut controversy

“Separate equipment ground” does this mean a driven ground rod connected directly to panel?

History.

Came upon a rebuild of a Hurricane Katrina house in which the “electrician” had installed a 125 amp service entrance with neutral / ground isolation capability, comingling grounds and neutrals, but had overlooked the need to supply electric range, cook top, hot water heater, and strip heaters.
Thus new large service equipment was installed for these loads and now also feeds the (original SE) now panel via the above described feeders.

Thank you kindly

[Jerry Peck - Codeman]

Sorry for the delay in this answer - I was out of town for the weekend.

1) B marked “suitable for use as Service Equipment “

Very good, that means that the neutral "can be" isolated from ground, and, in fact, probably means the neutral
'actually is' isolated from ground but is bonded to ground by either a ground bonding strap or a ground bonding screw, removing the bonding strap or the bonding screw will now allow the neutral terminal bar to again be isolated from ground (isolated from the enclosure, which is where the bonding strap or bonding screw bonded to ground).

2) 4 insulated conductors feeding regular panel

Also very good as that is what is required to allow the neutral to be isolated from ground. Now check this: 1) the grounding conductor is attached to a terminal bar which is attached to the enclosure and grounds the enclosure, making the enclosure ground; 2) the neutral conductor is attached to a terminal bar which is isolated from ground by being mounted on plastic supports which isolate (essentially insulates the neutral terminal bar from ground); 3) that there are no bare grounds on the neutral terminal bar; 4) there there are no insulated neutrals on the ground terminal bar; 5) that there is only ONE neutral conductor per terminal in the neutral terminal bar; 6) that the number and size of the conductors in the ground terminal bar match what is allowed on the label.

3) Neutral conductor in 2) has properly marked insulation

Good, otherwise it is not insulated, just "covered".

125 amp main breaker at this (former service equipment) now panel receiving hots from 125 amp breaker in new service equipment.

That is fine, the 125 amp main in the panel is simply a "panel main" and is an additional level of safety, just not a requirement (but I prefer to have a main in each panel as it does provide an additional level of safety, and remember, "code" is simply the "minimum" one is required to do, anything above and beyond code is even better).

If you clear me to isolate grounds and neutrals to get the panel safe and correct, ...

That is what is REQUIRED, yes - the neutrals are required to be isolated from ground in that panel as it is no longer service equipment.

I’m considering adding an additional “floating “ (sic) neutral bar wired to original neutral bar and an additional ground bar wired to original ground bar to facilitate picking up the shorter grounds and neutrals and avoid the butt splice wire nut controversy

THAT is a problem as you are only allowed to add terminals bars into the panel if allowed by the manufacturer on the listing and labeling, and I doubt that is allowed.

“Separate equipment ground” does this mean a driven ground rod connected directly to panel?

No. What that means is that you have a insulated neutral conductor with a separate grounding conductor, which could be insulated, covered, or bare, and that grounding conductor is simply officially called "equipment" ground, and it needs to be (as stated) "separate" from the neutral.

Came upon a rebuild of a Hurricane Katrina house in which the “electrician” had installed a 125 amp service entrance with neutral / ground isolation capability, comingling grounds and neutrals, but had overlooked the need to supply electric range, cook top, hot water heater, and strip heaters.
Thus new large service equipment was installed for these loads and now also feeds the (original SE) now panel via the above described feeders.

Unfortunately, that is not at all uncommon. What you are lucky about, and is usually also missed, is that the conductors which are now feeders (were 'service entrance conductor' originally) typically do not have a separate insulated neutral and a separate grounding conductor, which means that (usually) installations like yours would need the feeders replaced. From your description, though, you do no need to do that.

[nortonden]

Thank you Jerry

I'm most appreciative of your sage counsel

Last question

As the house is completed - no access to area around panel

and some grounds and some neutrals will be too short in panel to be landed
on their respective bars without spicing in panel.
Have read posts on your site re wire nuts and butt connectors.

Unclear as to what approved options I have for splicing

Thank you - best regards

Nortonden

[Jerry Peck - Codeman]

some grounds and some neutrals will be too short in panel to be landed
on their respective bars without spicing in panel.

Splicing is only allowed in the panel if the conductors terminate in the panel, i.e., splicing is not allowed to continue a conductor on through the panel as the panel is not allowed to be used as a raceway or junction box.

re wire nuts and butt connectors.

Properly rated wire nuts are acceptable provided you are using the proper number and sizes of conductors.

Very few, if any, butt connectors are intended for the solid conductors which you typically find in electrical wiring. I am not even a fan of using butt connectors for stranded wiring in electrical wiring installations. Cars and lower current electronic/electrical systems, sure, all the time.