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jhartz 02-02-2014 10:44 PM

Using multiple ground screws
 
So, I've been searching and searching for an answer to this one, but haven't found anything definite (i.e. backed up by code) yet.

I've seen it done before where, in a metal box, instead of pigtailing all the grounds together and then attaching to a ground screw, someone pigtailed half of them together and attached them to a ground screw, then pigtailed the other half and attached them to another ground screw. (It was a 2-gang box made from 2 gangable metal boxes, so there were multiple holes that were designed to accept ground screws.)

I think this seems easier if there are a bunch of cables entering the box; for example, instead of trying to tie 8 ground wires together and connect to a ground screw, just tie 4 together and attach to one ground screw, then tie the 4 others together and attach to another ground screw.

Obviously there's still continuity between the grounds, but is there anything in the code that would prohibit this?

sirsparksalot 02-03-2014 12:15 AM

No Code ref, but take all the grounds, twist them together just a few turns, and put on a crimp sleeve and crimp it down. You will then take the longest remaining wire and, using that as a pigtail, place that around the ground screw, and cut the rest off.

The other way is just plain hack!

rjniles 02-03-2014 05:41 AM

Quote:

Originally Posted by jhartz (Post 1300943)
So, I've been searching and searching for an answer to this one, but haven't found anything definite (i.e. backed up by code) yet.

I've seen it done before where, in a metal box, instead of pigtailing all the grounds together and then attaching to a ground screw, someone pigtailed half of them together and attached them to a ground screw, then pigtailed the other half and attached them to another ground screw. (It was a 2-gang box made from 2 gangable metal boxes, so there were multiple holes that were designed to accept ground screws.)

I think this seems easier if there are a bunch of cables entering the box; for example, instead of trying to tie 8 ground wires together and connect to a ground screw, just tie 4 together and attach to one ground screw, then tie the 4 others together and attach to another ground screw.

Obviously there's still continuity between the grounds, but is there anything in the code that would prohibit this?

If you have 8 ground wires in a box (2 gang), you need to review your wiring layout and box fill. 8 #14 cables and 2 devices would require a 42 cu in box. #12 would require a 47.25 cu in box.

stickboy1375 02-03-2014 05:53 AM

Besides possible box fill violation in this scenario, as long as it meets code I don't consider any installation hack, rather a preference.

Speedy Petey 02-03-2014 06:02 AM

Quote:

Originally Posted by stickboy1375 (Post 1300999)
Besides possible box fill violation in this scenario, as long as it meets code I don't consider any installation hack, rather a preference.

I agree. I see NO problem in doing it the way you propose, but work out a better way of laying out your wiring so that you don't have EIGHT cables in a 2-gang box.
If you are doing the "spider" or "wagon wheel" layout where multiple circuits are fed out of that one box that is NOT the way professionals would do it, for this exact reason.

carmusic 02-03-2014 09:04 AM

ive seen that a lot on metal box, we almost never use wire nut on gnd unless there is more gnd wire than gnd screw available :laughing: it make a cleaner box keeping the gnd on bottom of box

jhartz 02-03-2014 09:42 AM

Just for clarification, the example with 8 cables wasn't necessarily a 2-gang box; I just wanted to make another scenario where this might be useful... maybe a 5-gang box (for a bunch of switches in one location or something).

I know I would also have to look at box fill, and I can't actually think of a new work situation where there would be 8 cables, but it could be useful.

Oso954 02-03-2014 12:13 PM

In my opinion, splitting the grounds between two screws is bad practice. If you tie 8 grounds together and someone removes/fails to replace that ground screw, you have one box that is no longer bonded.

If you split the grounds between 2 screws and someone removes/fails to replace one screw, you have four cables and everything connected to them that are no longer bonded back to the rest of the system.

jbfan 02-03-2014 01:04 PM

Quote:

Originally Posted by Oso954 (Post 1301151)
In my opinion, splitting the grounds between two screws is bad practice. If you tie 8 grounds together and someone removes/fails to replace that ground screw, you have one box that is no longer bonded.

If you split the grounds between 2 screws and someone removes/fails to replace one screw, you have four cables and everything connected to them that are no longer bonded back to the rest of the system.

That is not the fault of the install, but the idiot that failed to make the connections that needed to be made.

Speedy Petey 02-03-2014 02:16 PM

Quote:

Originally Posted by jbfan (Post 1301179)
That is not the fault of the install, but the idiot that failed to make the connections that needed to be made.

Exactly. You could "What if.." almost any installation and call it bad practice.

JKeefe 02-03-2014 07:34 PM

Quote:

Originally Posted by Oso954 (Post 1301151)
In my opinion, splitting the grounds between two screws is bad practice. If you tie 8 grounds together and someone removes/fails to replace that ground screw, you have one box that is no longer bonded.

If you split the grounds between 2 screws and someone removes/fails to replace one screw, you have four cables and everything connected to them that are no longer bonded back to the rest of the system.

I can't see any argument for one of these scenarios being definitively worse than the other.

stickboy1375 02-03-2014 08:40 PM

Quote:

Originally Posted by Oso954 (Post 1301151)
In my opinion, splitting the grounds between two screws is bad practice. If you tie 8 grounds together and someone removes/fails to replace that ground screw, you have one box that is no longer bonded.

If you split the grounds between 2 screws and someone removes/fails to replace one screw, you have four cables and everything connected to them that are no longer bonded back to the rest of the system.

But it's not, because any hack will just hack it anyway...

Know A Little 02-04-2014 07:58 PM

Quote:

Originally Posted by Oso954 (Post 1301151)
In my opinion, splitting the grounds between two screws is bad practice. If you tie 8 grounds together and someone removes/fails to replace that ground screw, you have one box that is no longer bonded.

If you split the grounds between 2 screws and someone removes/fails to replace one screw, you have four cables and everything connected to them that are no longer bonded back to the rest of the system.

And this is done all the time (multiple Equipment grounds landed separately) in large junction boxes, panels and not an issue when the work is competed to code.

plummen 02-05-2014 01:45 AM

Quote:

Originally Posted by jhartz (Post 1300943)
So, I've been searching and searching for an answer to this one, but haven't found anything definite (i.e. backed up by code) yet.

I've seen it done before where, in a metal box, instead of pigtailing all the grounds together and then attaching to a ground screw, someone pigtailed half of them together and attached them to a ground screw, then pigtailed the other half and attached them to another ground screw. (It was a 2-gang box made from 2 gangable metal boxes, so there were multiple holes that were designed to accept ground screws.)

I think this seems easier if there are a bunch of cables entering the box; for example, instead of trying to tie 8 ground wires together and connect to a ground screw, just tie 4 together and attach to one ground screw, then tie the 4 others together and attach to another ground screw.

Obviously there's still continuity between the grounds, but is there anything in the code that would prohibit this?

Was it run with conduit between the boxes or is this a bunch of romex run to junction boxes youre dealing with?

jhartz 02-05-2014 03:37 PM

Quote:

Originally Posted by plummen (Post 1301799)
Was it run with conduit between the boxes or is this a bunch of romex run to junction boxes youre dealing with?

In my house, the example I found was just a few Romex wires going to boxes; it was mostly just a theoretical question. (And, if it were conduit, I sure hope there wouldn't be that many ground wires :laughing:)


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