Ground to metal box only - Should I address this?

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RCGA
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Ground to metal box only - Should I address this?

Post by RCGA » Mon Apr 17, 2017 6:30 am

Canadian home. Built in the late 60s. When I bought the home, many of the receptacles were two prong and at some point, they were switch to TR grounded receptacles.

Now, I guess who ever did the receptacle switch didn't think it was necessary to "bond" (not sure if that's the correct term) the box and the receptacle.

When you plug in a receptacle tester it passes fine, but is this okay to leave like this?
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Shannon
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Re: Ground to metal box only - Should I address this?

Post by Shannon » Mon Apr 17, 2017 7:24 am

Is there actually a ground wire coming in with the cables or is that ground wire we see just a short piece grounding the receptacle to the metal box only and does not go to the electrical panel??
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RCGA
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Re: Ground to metal box only - Should I address this?

Post by RCGA » Mon Apr 17, 2017 7:54 am

Here's another photo.

14/2 comes into the box with it's ground attached to the metal box only.

Receptacle has a ground attached to it and the metal box only, too.

14/2 and receptacle grounds never directly "touch"
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Aaron
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Re: Ground to metal box only - Should I address this?

Post by Aaron » Mon Apr 17, 2017 2:29 pm

Yep, you're good. You actually don't even need that short piece between the box and the receptacle. As long as the ground from the 14/2 is firmly secured to the ground screw of the box, your device will also be grounded by the yoke of the device.

Now, you should remove the screw retainers, those little plastic squares that keep the mounting screws from falling out. That ensures that the device makes good metal-to-metal contact when you screw it down, ensuring a good low-resistant bond.

It also looks like your white and black wires are "back-stabbed" into the receptacle. This is a fast and easy connection method, but not preferred and proven to have problems in some cases. Side-wiring receptacles is a better termination.

Lastly, I always like to remove the unused cable clamp in the box. I save the clamp and screw for future use. Just makes for a less-crowded box--not that yours is. Just my OCD, really.

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emtnut
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Re: Ground to metal box only - Should I address this?

Post by emtnut » Tue Apr 18, 2017 6:25 am

RCGA wrote:Here's another photo.

14/2 comes into the box with it's ground attached to the metal box only.

Receptacle has a ground attached to it and the metal box only, too.

14/2 and receptacle grounds never directly "touch"
The 2 ground connections are 'bonded' via the metal box. This is perfectly fine ;)

Hard to tell from the picture, but there should be a complete loop of wire around the screw on the box.

As Aaron said, if they are backstabbed, that should be rewired to use the screws on the receptacle.
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Shannon
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Re: Ground to metal box only - Should I address this?

Post by Shannon » Tue Apr 18, 2017 7:34 am

Personally I never rely on the device screws for the ground I always wire a ground directly to the device as well.
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Aaron
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Re: Ground to metal box only - Should I address this?

Post by Aaron » Tue Apr 18, 2017 11:14 am

Shannon wrote:Personally I never rely on the device screws for the ground I always wire a ground directly to the device as well.
Yeah that all but guarantees a perfect ground.

But as long as you have good device yoke-to-steel-box contact and as long as the incoming ground is really secured on the box's ground screw, it's just not necessary. If the box is sunken from the surface of the wall, I'd for sure use the ground screw on the device--I personally don't think the body of the mounting screw is sufficient. I want the yoke to actually be make direct flat contact with the screw tab of the box.

The advantage of NOT connecting a ground wire to the device is with a multi-gang box, it saves a LOT of wire-fill because you don't need pigtails for each device. You only connect all the grounds together with one pigtail to box. That's why, in the US, you should use steel boxes for 3 gangs or more. In Canada, all the non-metallic boxes have integrated ground bonding between all yoke screws and gangs, which is VERY nice. That's another thing that doesn't exist here.

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