With some Square D panels the covers are sold separately. Hence the model number difference. There may be one small sentence somewhere inside the PANEL label that states the wire sizes and number of wires for the neutral/ground bar. Look for "Wire range 4 -14" or something to that effect.
You should be fine with at least doubling up the grounds. If you need more room add another ground bar.
I'm completely confused. I thought the neutral and ground bars were bonded together. And, one of the ways of accomplishing that was a screw to the panel.
So, in that case, wouldn't the neutral wires be connected to the casing?
I recently had a post where I had the same set up as the OP (everything on the neutral bar--old 1960 panel). However, there was an unused ground bar in the panel and an electrician recently added some new grounds to it. I was concered that I forgot to ask him if that ground bar was bonded to the neutral. Everyone here said most likely the neutral had a "screw" that is hard to see that connects it to the box, and therefore they should be bonded since the ground bar is right on the metal box. So if that is true, then there must be current running through the metal case, which you say is wrong. Or am I misunderstanding your point?
-- John
there is a neutral coming in from the service, that should be connnected to the ground/neutral bus in the main panel. All neutrals should be connected to that bus, one per screw. If you don't have enough screws add an auxiliary one, and you can add ONLY GROUNDS to the added bus bar (note: I don't know if this is Code or not but it is a good idea) and you should also bond it to the original ground/neutral bus bar with some heavy gauge copper wire (also just my idea of a proper installation.) That way even without the bonding there is NO current flowing through the backbox unless there is a ground fault somewhere - it goes direct from the original bus straight to the service.
I have a book that says you can connect more than one ground under a screw BUT NOT NEUTRALS but I don't know if current codes have changed any or not. In any case it is a very bad idea to put more than one neutral under a screw; if that were to happen, you'd need to shut off the power to the whole house if you needed to remove one neutral from the bus for whatever reason. Otherwise, you could end up with a momentary open neutral on a live 120VAC circuit, and that can cause lots of damage.
nate
The enclosure is connected to the neutral bar (only in a service panel).
There should only be current on ground wires in abnormal events. It is permissible for that current to go from ground bar, through metal enclosure, to the bonding screw or jumper in a service panel, to the service panel neutral bar. The return path for the ground system may also include metal electrical wiring boxes and metal pipes with wires in them. Ground wires land on a ground bar, or only in a service panel on the neutral bar (the neutral and ?ground? are connected together only in a service panel).
Neutrals normally do have current on them. It is not permissible to use any metal enclosures as part of the return path for the neutral. If a ground bar has a direct wire connection to a neutral bar, connecting neutral wires is still likely not permitted. The wire connection is sized for short duration abnormal ground currents to trip a breaker, not for long duration neutral return currents. Neutrals may land only on a neutral bar.
I don't think the code has changed anytime recently. The book is right that the code explicitly does not allow more than one neutral in a terminal.
The book may be right or wrong on ground wires. More than one wire in a terminal is not permitted unless the terminal is 'UL' listed for more than one wire (110.14-A). If more than one wire is permitted, the label for the panel should indicate that. As gfretwell said "depending on brand".
If I understand correctly, the neutrals and grounds can't be attached at different points in the panel and if they are, a large shunt wire should connect the two so that the path of any abnormal current flow it through the large shunt wire between the two bus bars and not the metal of the circuit panel box.
I suspect that since the panel was not installed into a house with grounded outlets, the bus bar serves both neutrals and grounds. However, it's clear that the two grounded outlets that were added were not done by an electrician or even a talented amateur.
It would seem then, if I have to remove a neutral for any reason the main shut off has to be used to kill all power to the panel. That's always a good idea, even though it causes havoc with some of the VCR's and other electronics in the house. Better than dumping 220VAC through them, I suppose.
Thanks for your help.
-- Bobby G.
The solution to that situation would be to always kill the main breaker or even the outside shut off below the meter when disconnecting any neutrals, true? I'm just trying to figure out alternatives in case I am unable to find a supplemental neutral bus bar.
Thanks for you input!
-- Bobby G.
I've looked at a lot of panels in my neighbor's houses and yes, it appears to be quite common but that doesn't mean it's code! (-:
-- Bobby G.
I've copied down the numbers and taken some photographs to take to the local electrical supply shop. Hopefully, they know what's required in this jurisdiction. There are 100's of house in this neighborhood all built the same.
-- Bobby G.
I don't know if the picture of the panel made it through, but there are two bus bars at the top of the circuit breaker "stack" - one screwed into the other and the outermost one have two tapped screw holes that look like a third bar could be attached. The drawings on the label show three different models of this box - one has one bar, one has two and the third illustration shows three bars. What I need looks like a 8" strip of metal drilled with holes and accompanying setscrews. I'll report back when I get to the supply house. I was unable to get there on Friday so it's got to wait until Monday.
Thanks for your help!
-- Bobby G.
gether only in
bud,
Originally, gfretwell said "If you put a neutral on the supplimental bars you are putting circuit current through the metal can and the green bonding screw. (that is 250.6 for you code guys)"
And you said "Neutrals normally do have current on them."
OK, so let's forget about where they are "put", and look at the logic of the end result.
If the neutral and ground bars are bonded, it would seem to me that means they are unified, regardless of which one the wire lands on. IF the bond takes place through a screw that touches the panel box, then how is that not "putting current on the can?"
Not arguing. I actually learned all this stuff from you and others here. But this is the first time it occurred to me that the neutral current could be on the panel box because of the bonding as gfretwell said. So I am still confused about that point (not the issue of putting neutrals on ground bar). Can you explain why that bond (if achieved through a screw to the box) does not put the current on the box? I'm still confused!
-- John
We are talking about the path the current takes. Simply bonding the enclosure to the same bus the neutral is on does not take neutral current through the enclosure.
Now I understand what you're saying because I see that in newer boxes the ground bar is along the side and the neutral bar is physically about a foot away above the circuit breaker stack.
I went to the local supply house but all they had was a Cutler Hammer supplemental grounding bar (the set screws are all painted green) that looked as though it might piggyback onto the existing neutral bus bar. It doesn't. )-: I might be able to redrill and cut it to fit, but it seems to be as bad a solution as doubling up the neutrals with more than one to a setscrew.
I'm hoping now to find a supplier via the internet for the box. Hopefully I can find a:
Square D QOC-20MW supplemental neutral bus bar
somewhere on the net. Any pointers to good on-line suppliers appreciated. The Square D site (apparently now Schneider) had nothing listed under the QOC-20MW product number. )-:
-- Bobby G.
The solid neutrals for our loadcenters are built into the interiors. There are no UL rated supplemental neutrals made for that purpose. The only solution is to change the service.
I hope this will take care of you. Please contact us again if we can be of further assistance.
********************************************************************I'm not sure this is true of the older panels. The two tapped holes in the front of the bus look as if they would accommodate an auxilliary bar and the illustration on the panel label shows a configuration with three bus bars, not the two that are in the panel. The search continues . . .
-- Bobby G.
FWIW, it looks like the reason it's done everywhere is that the "by the book" solution is pretty drastic. As far as I can tell from what Square D said, to gain more neutral holes, I'll have to change out the whole box. That's a little too drastic a solution and I have a few options. One is to disconnect the central A/C since we never use it. That would free some openings. Another is to mount the supplemental Cutler Hammer ground bus bar in the case, feed it with a large diameter wire from the existing neutral bus bar and move the three or four ground wires now connected to the bus (old house, very few grounded outlets) to the supplemental ground bus bar. The third seems to be what most people do. Put two wires under a setscrew and print up a big label for the box "Disconnect Main Breaker Before Neutral Rewiring!"
-- Bobby G.
Why wouldn't you do it this way? this seems to be the easiest/safest solution, short of full panel replacement.
nate
I really don't like this idea, for reasons already discussed.
nate
Wht not just get a grounding kit and move over some grounds to free up some holes on the neutral bar. There should be tapped holes an a couple of places in the enclosure for ground bars. I still like to jumper them back to the neutral with a fat wire but the 10/32 screws are OK by code for ground busses.
If it comes down to availability, I would just get whatever neutral bar was available from the electrical supply. I know Lowes and Home Depot sell ground bars, but I am not sure if they have the neutral bars. You will probably need to drill and tap a few holes to mount it or use self drilling sheet metal screws.
Thanks for the photo BTW.
That's exactly what I did. Got a Cutler-Hammer grounding bus bar that looked like it matched what was in the box, but it didn't. It has machine screws, so I'll probably have to mount it with self-taps if I decide not to return it. It will allow me to remove some ground wires that are now mounted in the box's neutral bus bar and relocated them to the new ground bar. Oddly enough, if I do that, it free just enough neutral holes so that every breaker can have its own neutral bus bar set screw hole, which is probably how the panel was designed (this is old, two wire constructions from the 40's as you can see by the cloth insulation).
The scoop from Square D is that there are no supplemental neutral bus bars for that model box, but the illustration inside the box differs and the threaded screw holes on the front of the second bar say otherwise as well. I doubt the guy who responded was even *born* when my model box was sold, and I suspect their answer to a lot of questions like mine is "you need a new box." I will check out Lowe's and HD before I decide what to do on the off chance they have something the electrical supply house didn't.
Glad to see it made it through and that I am not under house arrest by netcops. I think it's important when asking for potentially hazardous advice to let people see what I am actually talking about because it may be very different from what they think I am describing.
Thanks again for all the help,
-- Bobby G.
If I decide to go that route, I will certainly jumper the ground bus to the neutral with the thickest wire I have, which is either a 10 or a 8. As I noted in the previous post, moving the grounds that are connected to the neutral bus to their own bus will free up exactly enough wires to accommodate all of the available breaker positions, as the box was probably designed to do.
Thanks for the help. Much appreciated.
-- Bobby G.
Primarily because I'm still convinced there's a supplemental neutral bar for this box somewhere in the world. The panel box illustration shows three separate neutral bars for the box I have (but mine only has two) and the frontmost bar has two threaded screw holes where a third bar could be mounted, so I still hold out some hope I can find something that will work. But I am reaching a point where I'm spending a lot more time than simply mounting the new ground bus bar would take.
I don't like it much, either, I must confess. I haven't looked closely at the box since I confirmed the new bar's holes didn't match the Square D's (it was close!) but I don't see any way to use the machine screws that came with the kit. I'm assuming that the correct place for the new grounding bus bar is along one of the two vertical sides of the box, but I haven't seen too many new boxes, so I'm not absolutely sure. There's not a heck of a lot of room inside this box compared to some of the newer ones and I am worried there won't be enough working room.
I first thought to mount it along the bottom, where there's a lot of free space but in looking at the photos, I see that the existing ground wires will be too short to reach and I'd have to wire nut some pigtails, something I'm not keen on. There is a lot less working room on the sides of the box, but if I mount it high enough, I can use the existing wire without having to extend them.
I have to admit, though, I am sorely tempted to take the four ground wires going to the neutral bus and put as many of them under one screw as will fit. That may or may not leave me enough open neutral connections on the bar to accommodate the new outlets. From what I can tell, that's legit to do with ground wires, but not neutrals.
Thanks for the advice!
-- Bobby G.
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