neutral/ground space (again)

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  #1  
Old 08-22-07, 10:17 AM
ddr
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neutral/ground space (again)

Iíve got a problem with space for neutrals and grounding wires:

Neutrals:
Iím reworking the layout in my Challenger panel, which has a 12/20 breaker capacity. The layout I was hoping for was using 19 breakers (one of which is 240DP), which would fill the panel and leave me needing 19 available neutral spaces.

The problem is, even though the two neutral bus bars installed each have 10 spaces available, two of these are used by the panelís grounding wires (which are bare stranded CU -- Iím guessing #6 or #4). One wire goes from the bar to the water main, the other goes from a second hole on the bar to a ground clamp attached to the panel frame.

I was hoping to avoid multi wire circuits, but replacing two SP breakers with a common trip DP would resolve that issue. Still, I wanted to clarify something: if the multi wire circuit goes to a j-box and splits so each hot has its own neutral before reaching any receptacles, does this remove the requirement to pig tail the wires to the receptacles to maintain neutral continuity?

Grounds:
The house had been wired with BX/AC so there were no grounding wires that needed bus bar space. Now that Iím using Romex and individual wires in conduit, I need a grounding bar.

The panel listed a ground bar kit to use but, after contacting Eaton/Cutler-Hammer, was told they didnít have specific cross reference parts for bus bars and to just look in the catalog for the size I need. Unfortunately, this doesnít give me any instructions that may have been specific to that panel.

The problem is Iím not sure where the bar would go: the neutral buses and the breakers are about 3Ē apart and there are holes about half way between them. Does it sound right to mount a ground bar between the breakers/neutral buses, or were these holes an alternate position for the neutral bars?

Also, the panel is mounted against a cement wall so the holes Iím referring to are only the thickness of the box, maybe an 1/8Ē. Is this sufficient to mount to? The screws seem to be at least twice as thick as the bar, do they make spacers?

Either way, if I were to drill my own holes, would passing one of the bare ground wires mentioned above through one of the grounding bar holes be an adequate bonding means?

As always, thanks in advance.
 
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  #2  
Old 08-22-07, 10:45 AM
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cable grounds

I'm not wholly sure of your situation, but it seems that the excess Romex ground wires could be fastened under one of the connector screws or wrapped around the cable entering the connector clamp (essentially doing the same as the BX). This may or may not meet with your local code or with the purists, but I see this done frequently around here.
 
  #3  
Old 08-22-07, 11:41 AM
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> if the multi wire circuit goes to a j-box and splits so each hot has its own
> neutral before reaching any receptacles, does this remove the requirement
> to pig tail the wires to the receptacles to maintain neutral continuity?

Yes, it removes the requirement. After the "separation" of the multi-wire circuit legs, you may treat each branch as its own circuit.

> just look in the catalog for the size I need. Unfortunately, this doesnít
> give me any instructions that may have been specific to that panel.

I agree, find one that is the right number of spaces and make it fit. Drill and tap your own screw holes if you need to. It's not ideal, but sometimes you've just gotta make do with older panels. Particularly those manufactured before the one-wire-per-screw rule.

> Does it sound right to mount a ground bar between the breakers/neutral
> buses, or were these holes an alternate position for the neutral bars?

No, usually the ground bar would go above or below the existing neutral bar(s). It's possible though, I can't think of the layout of a Challenger 12 space box.

> The screws seem to be at least twice as thick as the bar, do they
> make spacers?

They'll fit. The screws will dig into the concrete a little and the metal box will flex a little.

> would passing one of the bare ground wires mentioned above through
> one of the grounding bar holes be an adequate bonding means?

The metal box itself is adequate bonding for a ground bar; no jumpers are needed.
 
  #4  
Old 08-22-07, 05:26 PM
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Originally Posted by volts View Post
This may or may not meet with your local code or with the purists, but I see this done frequently around here.
This would not be permitted under the National Electrical Code.
Don
 
  #5  
Old 08-22-07, 09:42 PM
ddr
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Thanks for the info; looks like I'll be making my own holes. Now here's a question I think I already know the answer to:

Can the bar be mounted to the inside bottom of the panel where it would be easy to drill a hole or must it be attached to the back? (Yes, there are knockouts on the bottom.)

(Assumed answer: Absolutely not! Are you nuts?!)
 
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