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Code question about locating ground and neutral lugs seperate from a panel.

Code question about locating ground and neutral lugs seperate from a panel.

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  #1  
Old 11-20-13, 05:28 AM
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Code question about locating ground and neutral lugs seperate from a panel.

I'm trying to figure out if a wiring idea I have is code. I've searched through the NEC, but can't find anything that seems to directly address what I'd like to do. I actually have 2 different questions about 2 similar problems that are both sort of variations on the same theme.

First off, parents old house, my mother had her kitchen completely re-done in 1999 and the GC made a complete hash of the electrical work. Disposer and dishwasher on same circuit when both specify separate circuits. They added 5 new sabc receptacles and put them all, along with all the new under cabinet and in cabinet lighting, on the same single 20a circuit. They installed 1 GFCI and told me mom that it protected all the new outlets. Nope. It's hooked to nothing but a switch next to it for a small in-cabinet light. Also just lousy/messy wiring technique. Amateur grade stuff. I just discovered all this recently.

My plan is to run conduit from the main panel with 6ga THHN and then install a small Sqr-D 6/12 sub-panel in an out of the way spot in the kitchen. There's a spot in one wall that is perfect and is un-obtrusive. I'd like to cut it into the wall and flush mount it, and then I'm going to bore a hole up into the wall footer plate from the basement and pass a piece of 1.5" grey sched-40 PVC up from below and connect to the bottom of the new sub-panel's box inside the wall. That way, all connections to the sub-panel will run through this one piece of conduit. 3 - 6ga wires for 50amps of service and a 10ga ECG. (The basement is unfinished, and the kitchen-floor/basement-ceiling is easily accessible to repair the old wiring and run new wiring.)

Now here's the thought I had. Do I really need to run all the neutrals and grounds up into the sub-panel? I was thinking, that I could mount a grey Carlon 6"x6" or 8"x8" box on the basement ceiling on the bottom end of the 1.5" conduit that connects to the sub-panel. I could put isolated bus-bars in this box and then the 6ga white and 10ga green from the main panel would terminate at these bars. The various runs of romex from all the kitchen circuits would enter this box and their grounds and neutrals could all terminate at this point. The only wires that would need to run up the conduit to the actual sub-panel would be the 2 - 6ga hots from the main panel, and then the individual 12ga load side wires from each breaker. (And of course a piece of 10ga green to bond the sub-panel box itself to ground.) This would de-clutter the sub-panel and lessen by a great deal the number of wires that need to go up the conduit.

From a strictly electrical and mechanical viewpoint, I don't see anything wrong with this idea, but I have no idea if it's code.

Second issue:
And for the main prize, this house comes equipped with a 150amp Federal Pacific Electric Stab-lok main panel!

Yeah, I know, it's *Leaving* as soon as possible. The tragedy here, is that the house originally had a 70amp FPE main service(house built in 1959) and my father had it upgraded to 150amps in 1981. And he stayed with FPE so they could re-use the old breakers and save some money.
Crap...

There has also been all kinds of add-on/changes/deletions/re-wiring over the years, so the box is a real mess. A hodge-podge of original FPE breakers, and some American, Challenger, and UTI(I think that's the 3 letters. The grey Chinese FPE clones). A couple of 14ga runs going to 20a breakers. And the wires are all badly bent, rebent, and corroded from the years of modifications. I was examining the wiring, moved a couple of wires to see below them and all of a sudden had arcing at a breaker. I'd just bent the wire a couple of inches and it snapped off where it entered the screw on the breaker. When I saw that happen, as a first step I shut everything off and went down all the circuits and cut off the end of each wire and re-stripped them to get to some clean copper.

But this box has to go. And I'd really like to get rid of the wire in the box too. I've moved a lot of the new circuits to another sub-panel, but there are about 9 runs of the original silver-fabric late-50's romex coming out of the garage ceiling right above the main panel. The garage is built into the house under 2 of the bedrooms, so the garage ceiling is rock lathed and (real)plastered. There's only about 16" of fresh, unmolested old romex between the ceiling and where they enter the top of the old FPE panel.

I'd like to put a large junction box right up near the ceiling and bring all the old romex into this box and splice it to new pieces of THHN that would then go down a *short* piece of conduit into the new main panel.

My question here is similiar to the first one. Could I put 2 isolated bus bars in this junction box and terminate the grounds and neutrals at those bars? I'd bring a short piece of 2ga up from the main-panel for the neutral and either a 4ga or 6ga for the ground. This way, I'd only need to splice the 9 hot wires, and not all the grounds and neutrals too.

Again, this seems reasonable, but no idea if it's code.

Oh, and if I luck out and this is actually ok, what would be the best way to size the wire used for the neutral bar? The 9 circuits are all the original circuits when the box was installed at 70amps. They're all 15amp circuits that all mostly feed lighting circuits and a few bedroom receptacles. (Yeah, I know, I'd going to need CAFI's for those.)

But would a 2 or 4ga wire for the neutral be adequate, or would it need to be sized the same as the 2/0 neutral that feeds the 150amp panel?
 
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  #2  
Old 11-20-13, 06:10 AM
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Welcome to the forums! What a plethora of questions about problems. Yeah, stuff needs to be done. I'll only address one that I see may help with your situation. Why not just run your cable from the main panel downstairs to a sub panel in the basement. That would save the problem of running the individual cables from the basement to it. The forum has a bunch of qualified people that will guide you through this, so hang in there.
 
  #3  
Old 11-20-13, 06:13 AM
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The neutrals for the various branch circuits to be served by breakers in the subpanel must all come into that subpanel. Simply take the entire branch circuit cable out of the original panel and put it into the subpanel. If the original branch circuit cables don't reach, use a junction box to splice on extension cables. If you run conduit with individual conductors, you may not combine neutrals at the junction box running just one fat neutral the rest of the way to the subpanel. But you may combine the grounds with just one ground wire sized for the largest branch circuit coming into that junction box to continue to the subpanel.

Perfectly okay to choose a location for the subpanel some distance from the main panel if this eliminates having to install a junction box to splice on extensions for individual branch circuit cables.

Just one set of feed wires (hot, hot, neutral, ground) goes from the subpanel to the supra panel (main panel or another subpanel). The feed wires are sized for the breaker pair in the supra panel that protects the subpanel as if the latter were a single branch circuit, for example 40 amps for 8 gauge.
 
  #4  
Old 11-20-13, 06:39 AM
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Thanks for the reply. First off, I know how to do all this, not my first time to the rodeo, so to speak, but I just wasn't sure about the idea of putting the grounds/neutrals in a separate box that is a short distance from the sub-panel in one example, and a *really* short distance(less than 1 foot) from the main panel in the other example.

"Why not just run your cable from the main panel downstairs to a sub panel in the basement."

Uh, because I really want the panel in the kitchen so it's accessible from there. Elderly parents, stairs, long round-trip, etc. What I'm talking about is putting a large junction box *on the ceiling* directly under the sub-panel in the wall of the kitchen. The physical distance between sub-panel and j-box would be about 5 vertical feet.

The problem I see, is that once the romex comes into the j-box, it needs to lose it's outer sheath. Now, for the 9 circuits I'm currently planning, I've got 3 runs of 6ga THHN for the feed, a run of 10ga THHN for the EGC, and up 27 stiff pieces of solid 12ga to thread up that conduit, *for no good reason*. Or I can splice the solid 12ga from the romex to 12ga THHN in the j-box, which would be easier to deal with in the conduit, but then I've got to make 27 splices! Which, IMO, is just a mess. It's more sources of potential mechanical problems and voltage drops from resistance in the splices.

All of that could be dealt with far more cleanly by just putting the bus bars in the J-box and terminating the grounds and neutrals at that point. They aren't *needed* in the sub-panel. If they could be terminated in the j-box, then I'd only have 2 runs of 6ga, the 10ga EGC, and 9 runs of 12ga(either solid or stranded), for 12 wires total. Instead of 31 wires, 19 of which serve *no purpose* being in the sub-panel except to over-crowd it.

If this isn't permitted by code, what's the reasoning behind the code? I can't see any electrical reason to not allow it.
 
  #5  
Old 11-20-13, 06:45 AM
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Why not just run your cable from the main panel downstairs to a sub panel in the basement.
I have to agree with Chandler, put the new subpanel in the basement in the vicinity of the kitchen. Your idea of putting the subpanel flush in the kitchen wall will be much more difficult and not really serve any purpose being there. Each cable and all of the conductors from each cable must terminate on the appropriate bus or circuit breaker in the subpanel. You have enough issues to address without making it harder on yourself. In addition, you do not need 1 1/2" conduit. I would use a 1" conduit for 3 - #6 and 1 - #10......OR......run a 6-3 NM-B cable which would make it easier.

Disposer and dishwasher on same circuit when both specify separate circuits.
Actually, this is a quite common way of powering a disposer and dishwasher even today. I'll not dispute that maybe the dishwasher manufacturer specifies a dedicated circuit, but my recollection is they many times recommend a dedicated 15 amp circuit. IF this is a 20 amp circuit, I really don't think you would have a problem. Is it a 15 or 20 amp circuit? As far as a disposer, I don't think I've ever seen one that required the circuit be dedicated. Have you had problems with the dishwasher/disposer circuit breaker tripping?
 
  #6  
Old 11-20-13, 06:57 AM
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"I would use a 1" conduit for 3 - #6 and 1 - #10....."

Panel is being installed into a long-ago finished wall. Conduit is not only for the incoming service, it is also for all the branch circuits to leave the box back down to the basement, travel along/through the joists and beams and then back up into the various walls to their individual destinations.

And FYI, panel has to be in kitchen. Not basement. Basement not an option. Other factors dictate this. It *does* serve a purpose being in the kitchen. Not an item for discussion. Just take it as a given of the problem description. These aren't the droids you're looking for, move along...

As for the dishwasher/disposer issue, what I've read and been told is that if the manufacturer specifies that the item must be on it's own dedicated circuit then the NEC requires it to be wired that way. Yeah, a lot of them don't get wired that way, but as far as I know, it isn't code.
 
  #7  
Old 11-20-13, 07:27 AM
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AlanJ, thanks for the reply, but I think I made my post too long and confusing. I don't think you understood what I was asking.

To simplify: I have 2 completely different projects, but both involved a related issue.

The first project is putting a 50a sub-panel in the kitchen approx 50' from the main panel. I wanted to know if I could place the neutral and ground buss bars in a separate j-box about 5' below the new sub-panel on the ceiling below the wall that the new sub-panel would be mounted in.

-----------------------------------------------------------
The second project is that the main panel is a Federal Pacific Stab-lok panel, which is an accident waiting to happen. I want to remove/discard/dispose of/sh*tcan that POS 150a FPE main panel and replace it with a brand new 150a Square-D main panel.

The problem is that the original 9 circuits that were present when the house was built, leave the top of the FPE box, travel 16" up the wall, and then disappear into the plastered garage ceiling. I have no confidence in the quality of the sections of these wires that are currently inside the FPE panel. They have been bent back and forth many times over the years as various people made modifications in this panel. I fear they may have become work hardened and I've already had 2 of them just break off. The wire is also badly corroded from exposure to ghod-knows-what. (Father was a chemical engineer.)

When I replace the FPE panel, I want to just cut away all the old wire back to the top of the box where the cable anchors are and the old wire still has it's silver fabric outer jacket. At that point, the wire has only been bent once since it was installed in 1959. That wire should be in good condition and I feel I can trust it.

But if I cut the wires off at that point, I only have 16" of wire to work with. With the current design of panels, that leave a lot of space at the top and bottom of the panel, that's nowhere near enough wire to reach the individual CB's. Plus, I'd have to mount the new panel effectively up tight against the ceiling, which would violate the 76.5" to the top-most switch rule, and it would just be a really ugly way to mount a main panel. So, simply not an option.

So, If I want to snip off all the mangled wire and strip back the romex to get at wire in better condition, I'll need to either mount 1 large or several small j-boxes directly above the new main panel and splice the wires.

I was trying to find some way to make this splicing operation less of a pain. I thought if I can just have 1 large j-box, put the ground and neutral busses right in the box, then I could terminate them right there and that would be 18 wires I wouldn't have to splice.

<sigh> And so much for brevity...
 
  #8  
Old 11-20-13, 11:23 AM
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By mangled wire I meant just the half inch or so that went into the stab hole in a receptacle or the half inch or so that was twisted together with others and inside a wire nut.

But if you have reason to believe that longer portions of wire are apt to break inside the insulation, then you would have to consider cutting more off and splicing more on.

For both projects, the neutral bus bar may not be put in a J-box with a fat shared neutral continuing into the breaker panel.

A ground bus bar may be put in a J-box with a same size (sized for the largest amperage branch circuit) shared ground continuing into the breaker panel.

Properly made splices do not create a voltage drop problem.
 
  #9  
Old 11-20-13, 04:07 PM
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The one instructions says Recommended, not required. There is a difference.

I know you said you want it easily accessible for your parents, but, there should be little need for anyone to really access the panel unless working in it. Also all those conductors in the conduit would trigger the need to derate that many in the conduit. You would end up running #8's for a 20 amp circuit.
 
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