Doing a remodel, adding a couple of circuits, and the electrician says the sub panel is mis-wired. Here’s the details: There is a disconnect at the meter pole, then a main panel on the outside of the house at the corner closest to the meter (about 200 ft underground), then a sub-panel in the garage (about 100 ft inside the attic). When he opened the sub-panel, he discovered that it is 220v (feeds the oven, cooktop, dryer) but there are only three wires from the main panel: two hots and a bare that is landed on the neutral bar. No ground wire, no ground bar inside the panel. All the ground wires from the outlets are landed on the neutral bar, along with the neutral wires. House is 17 YO and there have not been any problems.
Sparky explains the problem, and I ask for a price to run a neutral back to the main panel, and re-terminate all the wires properly. He does a little checking, and comes back with the other half of the story.
The main panel is fed from the meter with three wires (aluminum): two hots and a ground. There is a ground rod visible at the meter pole, and it appears the disconnet is grounded properly. He says the underground conduit is properly sized for the fourth wire, but he’s not sure he can pull it in with the other wires in place.
Question: how serious is the lack of the neutral to the main panel, and the lack of a ground to the sub-panel?
Do it right, or do it twice.
Replies
Remain calm. All is not lost. Look or have the panel and its loads looked at more closely. If all of the loads served by this panel are 240v, not 240/120v, there is no problem. A neutral is not needed for 240v circuits. In this case the third feed conductor is a ground and should be bonded to the enclosure.
When I install a sub panel as a matter of course, unless there is a specific demand I don't and sometimes even then, I install a neutral even if it is not necessarily needed at the time of the installation. This increases the cost of the job a bit, four wire cable or four conductors versus three, but makes the panel much more adaptable and easier to work with later.
Some care has to be taken. Some 240v loads have control circuits or other 120v accessories and these cannot legally or ethically be connected into a panel lacking a neutral. Also some consideration has to be made for replacements in time. Installing a new unit with a 120v control circuit makes you either rerun the feed, go a longer distance to another panel or to, unfortunately this happens too often when an uninitiated worker trying to make it work, place a neutral load on a ground.
I could be wrong, but I believe the code specifies a neutral and ground for sub panels, though the two should not be bonded at that point. I think the reasoning is that somewhere down the line, It`s a given that 110 v will eventually be taken off and most people will take the short-cut route, ie, the ground as neutral. Will it work? Probably. Is it advised? Probably not. I`ve found that many people try to get by with their electric on the cheap. I won`t do it or advise it. Though I think the code can be overkill sometimes, I`ve grown to like overkill. Them electrons is 'wascally wascalls' sometimes. Better to er on the safe side.
Sorry, left out a minor detail. The sub-panel in question feeds 3-4 220v circuits, and all of the 110v circuits. The main panel feeds 2-3 220v cvircuits, and the sub-panel. I'll get some pics today. Now what say yee?
Do it right, or do it twice.
Sub Panel must have a ground buss added. The gound wires that are tied into the neutral buss must be moved to the ground buss. This ground buss must be grounded either to the main panel or to a suitable ground (water pipe or gound rod as code provides).
Not sure I understand about the main breaker not having a neutral. Your service should have two hots and a neutral coming into the house.
You don't have a main pannel and sub-pannel.
You have TWO SUB-PANNELS. The main "pannel" is at the disconnect.
While rare, it is potentially very dangerous.
If the neutral connection back to the main disconnect is lost them all of the "grounds" will be come hot.
So the case of the refigerator or stove might have 120 volt on it while the sink is still grounded through the piping.
You don't have a main pannel and sub-pannel.
You have TWO SUB-PANNELS. The main "pannel" is at the disconnect.
I was thinking the same thing, but wonder if the fact that the disconnect is at the pole instead of at the house makes a difference.
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Your mileage may vary ....
On of the purposes of "grounding" is bonding. That is make sure that all nominal non-current carrying metal is at the same potential.
To do that you can have one and only one point where the neutral and ground are connected.
In a case like this I don't know why the code picks the disconnect as at point, but they do.
Personally I don't see any reason that it can't be at the "big pannel" and still have an upstream disconnect. But that is not the way that the code reads.
But what is sure is that there only be that one point.
Thx
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Your mileage may vary ....
He needs a neutral from the "main" to the "sub".
'not sure he needs a ground from disconnect on pole to "main", however, as they aren't in the same building. Under NEC 250-32(b)(2), he would just need a ground electrode system installed at the house, no?
With due respect, I think I have a main panel (at the disconnect) although it has no breakers, and a sub-panel at the corner of the house, and then a sub-sub-panel in the garage. If the garage panel went back to the disconnect on home runs, then I would agree with two sub-panels. But I'm not an electrician, fortunately :)
I asked my sparky about driving a ground rod at the first sub-panel, and he said that was not code because they are too far apart and there is the potential that the sub-panel and the disconnect would be at different ground planes. And the conduit from the disconnect ot the first panel is pvc, so there is no connection at all, even though you can't use the conduit as a ground.
Do it right, or do it twice.
Edited 9/5/2003 8:49:11 PM ET by ELCID72
It doesn't matter if they are at different ground planes, if the neutral is bonded to the ground electrode at the subpanel (i.e., the first panel). Ordinarily, you're not allowed to do this, but it is permissable in the code if the main and sub are not in the same building andthere is no other metallic connection between the two buildings (or the pole and the building in this case). Bonding the neutral to gound at the sub ensures that sufficient fault current will flow to trip breakers in the subpanel, should a fault occur. Since there is no other metallic connection between the two structures, ther is no chance for "sneak currents" to flow between the structures, which is ordinarily a concern when ground and neutral are connected at a sub (i.e., some of the neutral ends up flowing through grounded metal components).
Here's two pics of the situation: the disconnect and the garage sub-sub-panel. The disconnect shows three wires entering the conduit: two hots and a neutral, no ground wire. The garage panel has four 240v breakrs (top two on each side) and a bunch of 120v breakers. The branch wires for the 240's are a black hot to one terminal, a white hot to the other, and a third wire to the neutral bar. I thought the hots had to be colors, not white.
If you look closely at the 120v breakers, you can see the white neutral and the bare ground under the same screw.
We checked one of the other disconnects (there are 4, it's a horse ranch with multiple buildings) and the installer cut away some of the aluminum conductors because the cable was too big to fit into the clamp on the fuse holder.
Do it right, or do it twice.
Edited 10/16/2003 10:13:52 PM ET by ELCID72
Ok, now that I have given more info, back to the original question...is this a dangerous situation, or just a hassel? The HO has already approved the expense of adding the new wires, so that's not an issue...just like to know how bad it is.
Do it right, or do it twice.
The branch wires for the 240's are a black hot to one terminal, a white hot to the other, and a third wire to the neutral bar. I thought the hots had to be colors, not white.
Around here, the inspectors will make you put red tape on the ends of any whilte wires used as a hot, such as 240V circuits, or travelers in 3-way lighting circuits.
The grarge panel definitely needs a neutral connection. The neutral and grounding buses are kept separate in the panel. The present situation is not code-compliant and can be dangerous. You can end up with things like the HO getting shocked by heating ducts.
At the house panel, you need a grounding electrode per the NEC, no matter what you do; all buildings served by more than one branch circuit need their own grounding electrode.
You can run a grounding conductor from the disconnect to the house panel; this will be compliant, if the neutral and grounding conductors are not bonded at the house panel.
Or, if and only if you don't run the grounding conductor to the disconnect, you can bond the neutral and grounds together at the house panel. Ask the electrician and/or inspector about section 250-32(b)(2) and see if it's applicable here (I've run into one or two electricians that weren't familiar with this section).
Regarding the AL conductors pared down to fit in the terminals, that sounds worrisome. On big properties, it's pretty common to use AL conductors on feeders to outbuildings that are much larger than the required current rating, in order to keep the voltage drop acceptable. At my place, I have 4/0 AL wires running to the horse barn for a (long) 100A feeder. Wires this big won't fit in 100A breakers. However, the correct way to do this is to put on 2/0 pigtails, using approved connectors. If these were copper wires, I wouldn't worry too much about cutting off a few of the strands and connecting to the breaker, but AL makes me nervous. I've seen a few high-amperage AL connections that have overheated due to high resistance in the connection that developed due to sloppy mechanical connections. The results were scarey: melted wire insulation, terminal blocks melted away and burned, etc.
Thanks for the info. We arrived at the concl;usion that it is dangerous (to some degree) and have made plans to pull the correct wires from panel to panel to disconnect.
The pared down AL terminations are for a 100A service to a barn. There is no evidence of arcing, but you can tell that he had a hard time with the connection.
Do it right, or do it twice.