Electrical - grounding J-Boxes

[Greg Peterson]

I am installing a partial new circuit. The part from the service panel to the existing wire. The romex has a ground wire, the existing/original wire does not. The house has a grounding system, so the grounding wire in the romex does go to ground.

Do I just clip this ground wire to the inside of the J-box or screw it into the body? I assume this is how you ground the J-Box. Is there a preferred method? What about where two ground wires come into the box, can you just pigtail those then?

[Larry Reimer]

Metal junction box, right? Yes, the ground wire needs to make a good mechanical connection with the box. Easiest way is to put a screw in the back of the junction box and wrap a loop of wire around that.

When you have multiple ground wires coming through the junction box you connect those together and add in the "pigtail" wire that is hooked to the junction box itself.

You talk about hooking the new grounded circuit to an existing ungrounded circuit. That would concern me more than the grounding method used in the junction box. One way to make that ungrounded circuit safer is to install a GFCI receptacle and use the load side of the receptacle to connect the ungrounded wire that continues on. Or put the whole circuit on a GFCI breaker.

[Mike Seals]

I am installing a partial new circuit. The part from the service panel to the existing wire. The romex has a ground wire, the existing/original wire does not. The house has a grounding system, so the grounding wire in the romex does go to ground.

Do I just clip this ground wire to the inside of the J-box or screw it into the body? I assume this is how you ground the J-Box. Is there a preferred method? What about where two ground wires come into the box, can you just pigtail those then?

I'm a tad confused as to what you are trying to do, the house has a grounding system? Is this a newer house, post 1970s that has the three prong plugs or is it an older house that has been updated?

Please elaborate, if you tie grounds at the wrong spot, it can cause some odd happenings. There is a difference between grounds and neutrals and many times they get crossed at the wrong location.

[Greg Peterson]

House is 1959 vintage. 100 amp service, ungrounded.

New service is 200 amp, and ground system is now installed and hooked up to new service panel. No power hooked up to the new service panel yet. Utility wanted the new service entry located closer to the front of the house, therefore all new equipment has been installed in new location. Since I only have nine existing circuits, from 1959, it was easier to simply run romex from the new service, and J-Box into the existing, ungrounded circuits. This makes the cutover pretty easy. Just pull out the existing wiring from the existing service panel, run it to the J-Box, splice it into the new romex that runs back to the new service panel. Total down time should only be about fifteen to twenty minutes.

A couple of the J-Boxes will house two circuits (using large J-Boxes), therefore I will have two ground wires (not to be confused with nuetrals) that will need to be grounded.

[Jim Becker]

Greg, ground the metal boxes per the previous post early in the thread. And your intended method must be pretty standard for tying new service to old circuits...there are good examples of that in my basement done by licensed electricians both pre- and post-purchase of the property by us.

That said, if there is any way to pull new wire to any of the existing circuits do it. If not, consider using GFCI outlets (which can be used to replace non-grounded outlets in a retrofit situation). I did that for a few circuits/outlets in the 250 year old portion of our home. Despite "updated" wiring sometime in the last century (no knob and tube, but early non-grounded "romex" and BX), I was totally uncomfortable with ungrounded circuits that are in place. (I plan on pulling new wire to at least the first floor outlets and any second floor points that I can manage to get to) I also put Arc Fault Breakers on the bedroom links.

If any of the old circuits are appliance circuits in the kitchen...definitely consider doing whatever is necessary to re-wire.

[Rob Russell]

You need to terminate the equipment grounding conductor on the j-box with an approved/listed connection. You can buy the green grounding screws at any home store and they are inexpensive. The metal j-box will have a drilled and tapped hole specifically sized for the green grounding screw. Just use that and you'll be fine.

[Greg Peterson]

Thanks guys.

First step is just getting the service updated. I have replaced a couple of circuits, or rather I am not going to J-box a couple of the old circuits as it would have cost more in wire and time than to just run to the location (washing machine and dryer).

As for the rest of the existing wiring, GFCI is a good idea. I do have the bedrooms currently on AFCI breakers. Can you put a GFCI outlet on an AFCI breaker? I don't know if there is a condition where one could defeat the purpose of the other, or if these two types of protections can interfer with the proper operation of the other under the right set of circumstances.

[Alan Trout]

You can also buy a green grounding clip that is ok that you can ground to the box. I have used both and both work fine. I think the screws can be found in smaller packages than the clips.

[Paul Simmel]

As much as everyone here would like to jump in (good souls as we are) and help Greg with his electrical question, (which is not understandable without various interpretation) I would advise Greg get an electrician ASAP! To have to explain that neutral and ground are different, and that they shouldn’t be crossed, is inviting (fill in the blank).

Electrical advice is scary enough even with clear questions.

Greg, with all due respect, get someone to finish off your installation and then read up before for the next upgrade.

[Greg Peterson]

I agree that these things can be made confusing. I'm not sure how anyone got the impression that I was confused about ground and nuetral, but it happened.

I was just looking to find preferred method of grounding j-boxes.

Thanks for the input fella's.

[Paul Simmel]

Greg,

You don’t say if your new j-box is plastic or metal, if your existing electrical system is ridged pipe/emt/romex, but you say you are running Romex from a new service to “j-boxes”… and you want to know if you should “clip” the ground wire. Furthermore, (if I read this correctly) you are using these j-boxes as intermediate connection points from a new service to the existing house/shop system that you state is “ungrounded”.

How so, “ungrounded”?

[Jim Becker]

Paul, I took the "ungrounded" as being just like some of the outlets in the historic portion of our home...hot and neutral only. No third wire for earth ground at the outlets. Very common in 1950's vintage (or older) structures that have not been re-wired.

[Greg Peterson]

Jim, you are absolutely correct. The original wiring consists of a hot and a nuetral, no ground wire. This is not uncommon, at least in my neighborhood and according to county inspector. Initial inspection passed with flying colors. Just wanted the J-Boxes grounded, which is a five minute fix.

The J-boxes are metal. Runs from new SP to J-Boxes are Romex.

Service Panel - Romex through attic to metal J-Box - Splice original hot wire to Romex hot wire/ original nuetral to Romex Nuetral - mechanically fasten ground wire from Romex to metal J-Box.

I installed two eight foot, copper clad grounding rods, eight feet apart, are wired via #4 stranded to the ground on the new service panel, so a path to ground exists from the ground J-Box, but no path to ground exists from the outlets or switches in the house. I will have to fish new Romex to these branch circuits if I want the existing circuits to be grounded. Of course, any new circuits I add will be grounded, so I only have to worry about retro-fitting the original ungrounded circuits.

[Jim Becker]

Again, you can use GFCI outlets in any of the ungrounded outlet locations that have greater potential for risk due to location or use. I wouldn't bother for simple two-wire lamps, but would for other more general utility locations in lieu of those three to two converter plugs which strictly speaking are still supposed to be grounded via the screw...and that doesn't happen on outlets like we are describing. GFCIs are costly, but in lieu of pulling the new cable "now" could be a life-saver.