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Upgrading two-prong receptacles - are these wires already grounded?

Upgrading two-prong receptacles - are these wires already grounded?

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Old 02-28-17, 08:03 AM
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Upgrading two-prong receptacles - are these wires already grounded?

Hi All -

This is something I haven't seen before so I want to ask you before proceeding. I'm working on wiring that is a variety of ages from 1950's to modern. The house has a lot of old two-prong receptacles that I'm upgrading to 3-prong with proper grounding.

My questions: why is the ground wire clamped into the cable entrance clamp, and is there an easy way to extract the ground wire from its clamped position to attached to a receptacle?

In one wall (both sides of which are exposed to living spaces), there are two old two-prong receptacles pretty much back-to-back that have wiring with a ground wire that is folded back and clamped into the cable entrance clamp. Here is one: Name:  IMG_5664.jpg
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Here is the other, which has both an older 3-wire cable and a newer 3-wire cable coming in, both of which have the ground wires folded back and clamped into the cable entrance clamp:Name:  IMG_5663-1.jpg
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I have never seen a ground wire clamped in this manner, but it appears to be intentional as all three cables are clamped like that. Can anyone tell me why they are like that?

Also, I am hoping (and will verify before proceeding) that the ground wires are in fact connected to proper grounds. If this turns out to be the case, then I would like to use them for new 3-prong receptacles. Any suggestions about how to get to these ground wires? They appear to be firmly clamped, so I'm not confident that I can simply pull them loose so the ends are exposed & available.

tia!
 
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Old 02-28-17, 08:40 AM
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Quick question on old 2 prong outlet was there a ground screw?
 
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Old 02-28-17, 09:29 AM
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That was a quick and easy way to ground the box. Catch the ground wire in the clamp.
I've seen it quite often on older houses where the ground wire wasn't required for the receptacle.

You should be able to squeeze a small screw driver between the plaster and the box to loosen the two screws. You need to pull the cable into the box to grab the ground wire or try to just grab the ground wire.

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Old 02-28-17, 09:50 AM
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"Quick question on old 2 prong outlet was there a ground screw?" - No, just hot and neutral.
 
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Old 02-28-17, 09:53 AM
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PJmax - thank you very much for both of your comments. Re. the picture of the clamp, I'm glad you added that. I knew what the clamp looked like beforehand, but seeing the picture made me realize that it should be possible to get at the screws, like you said. I was thinking I'd have to open up the wall but your idea should work. Most appreciated!
 
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Old 02-28-17, 10:04 AM
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Pete--Typically it's just pinched in the clamp and not wrapped around the screw?

Is this acceptable today? If so it would be easy to add another ground (screw or clip to box) to the new receptacle.
 
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Old 02-28-17, 12:09 PM
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It is not acceptable today. All grounds should be spliced and connected to the device and any metal boxes.
 
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Old 02-28-17, 01:14 PM
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Often the ground wire will be clipped short in those old boxes. I find it helpful to use either a push-in wago connector or a copper barrel crimp to extend the stubby ground to a useful length.
 
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Old 02-28-17, 04:22 PM
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Thanks for all your comments! They are all very helpful.
 
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Old 02-28-17, 05:42 PM
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It's 50-50 whether the ground is wrapped around one of the clamp screws.
Give it a good tug. If it breaks you can splice it like mentioned.
 
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Old 02-28-17, 08:10 PM
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Success! I was able to loosen the clamping screws without much difficulty. The ground wire *was* looped around one of the screws, but it was only a 180 degree loop (not round and round) so it was easy to unloop. I was able to pull the ground wire back up into the box without much problem. Name:  IMG_5668.jpg
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Old 02-28-17, 08:25 PM
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Good job! Thanks for letting us know your success.
 
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Old 03-01-17, 06:08 PM
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Thanks, and you're welcome!

Final update - I rewired the other receptacle as well (the one with two cables coming in) and everything went equally smoothly.

Also, I inadvertently discovered that both receptacles are switched along with the overhead light, which goes a long way towards explaining why the receptacles seemed to only work intermittently. ;-) In any event, now the receptacles are new and grounded.
 
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Old 03-01-17, 06:20 PM
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discovered that both receptacles are switched along with the overhead light,
I shouldn't be too hard to make them hot all the time. Let us know if you have questions.
 
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Old 03-01-17, 06:41 PM
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OK, will do - thank you. The wiring in this place is really something, so there are sure to be questions. ;-)
 
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