OT- Electrical

Re: OT- Electrical

Bill Howatt

I'm in Canada but our codes are usually the same or close to it.

The main panel normally has the (safety) ground and common (white neutral) tied together. Usually with a bonding screw that can be removed to isolate them if necessary but this is not done at the main box.

The safety ground should never have any current running in it except for fault current and this means it cannot be used as a common.

The sub-panel must not have the common and ground tied together. This is a case where the bonding screw mentioned above is removed so it doesn't happen. For a normal installation, the reason is that if they are bonded in the sub then you have 2 parallel connectors going back to the main and this means some common current will be carried on the ground (it will divide according to the resistance of each of the two wires back to the main).

A GFCI will work without a ground but the outlet should be grounded.

Rewire I think is best.

Bill

Re: OT- Electrical

Lee Schierer in McKean, PA

I don't believe that is correct. The NEC prohibits using ground wires as current carriers.

Lee

Re: OT- Electrical

Bill Houghton, Sebastopol, CA

Yep. You've got work to do. The neutral (white) wire and equipment ground (green or bare) wire are bonded at the main box, but NEVER at subpanels. Best practice, even at the main box, is to have a buss bar for the neutral and one for the equipment ground, with the two tied together in some manner (often, as Bill Howatt indicated, by way of a bonding screw that runs the bond through the frame of the main panel.

My son can testify that "pros" do stupid electrical stuff all the time.

Re: OT- Electrical

John in NM

My understanding of it is roughly the same as yours, however I'm not a pro and I haven't pulled a permit (NM allows permitted work done by homeowners) in 15 years.

To answer #1, the grounding arrangement described is kosher at the main panel, but the sub panel should have a white wire going to a buss bar insulated from the panel box, as well as another buss bar bonded to the box for the grounds.

#2 - no, keep the common and ground separate everywhere downstream of the entry panel (ie: breaker panel nearest the meter).

It will work either way (though nuisance trips of the GFI's are possible, depends on how good the ground is), but the code as I understand it is that it won't pass with a sub panel bonding common and ground. Even if the sub panel has its own ground electrode it needs to be tied to all other ground electrodes to ensure that ground is the same everywhere.

Possible work around would be to go a foot or so upstream of the sub panel, put in a remodel box and tie in a length of white #10 that will reach the sub-panel. Add an insulating buss bar for the common in the sub panel and then put a blank cover on the remodel box. It's a bit of a pain and kinda redneck, but it's less trouble than re-running the feed to the sub panel.

Re: OT- Electrical

Mark Nowicki

NEC does allow using metallic conduit as a grounding conductor.

Others have mentioned about the sub-panel bonding.

Things might not be pretty but might be to code.

Before ripping everything consult a reputable sparky, as easy as finding a reputable lawyer.

Re: OT- Electrical

Ed Wozniak

I think you could consider using the green insulated wire as the common. It would be the wrong color but electrically correct. Then install one or two (depending on code) grounding rods and connect them to the garage panel box ground bar. This could be an option if installing grounding rods is less work than running a new feed from the house to the garage.

Re: OT- Electrical

Larry Clinton At Frankfort, (Central) Indiana

First disclaimer, I used to be an electrician but haven't kept up with codes for several years but what I am writing below was code when I did electrical work!

Metal Conduit is acceptable as an earth ground in most (not all, recommend checking with your local building inspector) localities. A green wire is also acceptable. If the conduit is used as the ground the main box must have the grounding screw installed and a ground wire installed in each outlet box connected to the box (under a screw) and wired to the "green" screw of the outlet or switch itself.

Any circuit with any portion of the neutral or "hot" line being 14 Gage must be protected with no larger than a 15 amp breaker.

The use of metal conduit for grounding purposes has been disallowed in some areas, especially in extremely humid areas and those near the ocean. This was due to corrosion occurring where the conduit attached to the boxes. There were cases where the entire home ended up with a short causing all grounded equipment becoming "hot" resulting in persons being shocked and as I remember (not sure) some deaths. As I remember California and Florida and some other states outlawed the use of grounded conduit!

Re: OT- Electrical

Keith Newton

Instead of ripping it ALL out, can you cut into the 10-3 WG somewhere close to the sub-panel, then use a junction box to pick up the white from there on into the sub?

Thanks - Update

Mark Mandell - Gone Round In New Jersey

Found the white wire in a splice box behind a cabinet where the feed came through the wall. The dummy appeared to have run out of wire of the correct colors, so white became black, black changed to green, red stayed red, and the ground went through the metal conduit. Small wonder the tester showed an open ground in the circuit coming out of the sub.

Went to the supply house and got an insulated supplemental buss to put in the sub box for common wires plus 10' of #6 (not stranded wire in the right colors.

All's well that ends well.