Receptacle Wiring
#11
I am replacing the receptacles in a bedroom we are updating.  I usually check the wires for voltage to make sure I am seeing what I expect.  I pulled one receptacle and it had two cables - one coming in from another receptacle and one going out to the next receptacle.  I checked the incoming pair (lets call it pair 1) blk to wht and got 120 volts.  I checked the outgoing pair (lets call it pair 2) and got 0 volts.  All of that is as expected.

I can't say that I ever did the next checks before:
1.  pair 1 wht to pair 2 blk - 0 volts  as expected
2.  pair 1 blk to pair 2 wht - 79 volts  unexpected
3.  pair 1 black to pair 2 blk - 90 volts unexpected

I installed the new receptacle and checked it with a plug in tester - test OK

So are the unexpected results typical or do I have a bigger problem
Thanks
Rick
Rick

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#12
I am a bit puzzled by your results. First, just to make sure we are talking the same nomenclature – I assume when you refer to “pair 1 white” that is reference to the white – or neutral of the black and white incoming (or supply) pair and that “pair 2” of the outgoing black/white pair. A sketch would be helpful.

First, based on what you are describing it does not sound like the (duplex?) receptacles are/were  properly made up. Both the incoming white (neutral) and black (hot) wires should be bonded in the box with pigtails connected to the receptacle (s) – unless it is the last receptacle on that particular circuit. And of course all the grounds should be bonded thru the box See sketch below. There should always be a (120 vac) voltage reading from either side of the receptacle (see sketch below).

Using your nomenclature and assuming my sketch accurately describes your situation:

1.      pair 1 wht (w1) to pair 2 blk (b2) - 0 volts  as expected – should read 120VAC
2.  pair 1 blk (b1) to pair 2 wht (w2) - 79 volts  unexpected - should read 120VAC
3.  pair 1 black (b1) to pair 2 blk (b2) - 90 volts unexpected - should read 0VAC

FWIW – the 79-volt and 90-volt readings are a bit bothersome. It sounds like the neutral potentially might be “floating and not properly bonded to ground at the sub-panel.

   
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#13
(01-13-2023, 05:17 PM)Don_M Wrote: I am a bit puzzled by your results. First, just to make sure we are talking the same nomenclature – I assume when you refer to “pair 1 white” that is reference to the white – or neutral of the black and white incoming (or supply) pair and that “pair 2” of the outgoing black/white pair. A sketch would be helpful.

First, based on what you are describing it does not sound like the (duplex?) receptacles are/were  properly made up. Both the incoming white (neutral) and black (hot) wires should be bonded in the box with pigtails connected to the receptacle (s) – unless it is the last receptacle on that particular circuit. And of course all the grounds should be bonded thru the box See sketch below. There should always be a (120 vac) voltage reading from either side of the receptacle (see sketch below).

Using your nomenclature and assuming my sketch accurately describes your situation:

1.      pair 1 wht (w1) to pair 2 blk (b2) - 0 volts  as expected – should read 120VAC
2.  pair 1 blk (b1) to pair 2 wht (w2) - 79 volts  unexpected - should read 120VAC
3.  pair 1 black (b1) to pair 2 blk (b2) - 90 volts unexpected - should read 0VAC

FWIW – the 79-volt and 90-volt readings are a bit bothersome. It sounds like the neutral potentially might be “floating and not properly bonded to ground at the sub-panel.

Don - I probably wasn't clear - the receptacle was pulled and all wires disconnected.  My readings were on the actual wires after being disconnected from the duplex outlet.  Not sure if this changes your thoughts at all.  Yes - pair 1 is the incoming source blk/white and pair 2 is the outgoing cable blk/wht.
Rick
Rick

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#14
(01-13-2023, 05:57 PM)Rick_B Wrote: Don - I probably wasn't clear - the receptacle was pulled and all wires disconnected.  My readings were on the actual wires after being disconnected from the duplex outlet.  Not sure if this changes your thoughts at all.  Yes - pair 1 is the incoming source blk/white and pair 2 is the outgoing cable blk/wht.
Rick

Got it. Then that makes a little more sense to me. In the case of your test 2 and 3, I assume the neutral (pair  2 white) is not connected to ground anywhere downstream of the receptacle (FWIW – it should NOT be) and so the black (i.e., “hot”)  is floating with no reference to ground and this can result in strange readings. You may as well have connected second (non-hot) probe into a pumpkin and got the same results!

Having said this, the diagram show is the correct way to wire an outlet and at a minimum the thru circuits should be bonded in the box
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#15
(01-13-2023, 05:57 PM)Rick_B Wrote: Don - I probably wasn't clear - the receptacle was pulled and all wires disconnected.  My readings were on the actual wires after being disconnected from the duplex outlet.  Not sure if this changes your thoughts at all.  Yes - pair 1 is the incoming source blk/white and pair 2 is the outgoing cable blk/wht.
Rick

If your meter has a low Z setting use it and it will drop to zero.  Most meters have a high impedance which causes the reading.  The low Z setting places a resistor across the input and will drop the reading to zero unless there is a issue.   Roly
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#16
(01-13-2023, 07:33 PM)Roly Wrote: If your meter has a low Z setting use it and it will drop to zero.  Most meters have a high impedance which causes the reading.  The low Z setting places a resistor across the input and will drop the reading to zero unless there is a issue.   Roly

Thanks guys - sounds like everything is OK - don't know why I suddenly decided to check the pairs this way.

Here's another question unrelated to wiring - what is he best way to compensate for boxes that are set in little deep.  This results in the receptacle sitting a bit below the wall and the cover plate not fitting correctly.  Should you leave the receptacle screws in the box loose and let the cover plate pull the receptacle tight or should the receptacle be shimmed behind the box screws?

Rick
Rick

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#17
(01-14-2023, 05:20 AM)Rick_B Wrote: Thanks guys - sounds like everything is OK - don't know why I suddenly decided to check the pairs this way.

Here's another question unrelated to wiring - what is he best way to compensate for boxes that are set in little deep.  This results in the receptacle sitting a bit below the wall and the cover plate not fitting correctly.  Should you leave the receptacle screws in the box loose and let the cover plate pull the receptacle tight or should the receptacle be shimmed behind the box screws?

Rick

They should be shimmied. 
I like these from amazon

https://smile.amazon.com/gp/product/B00A...=UTF8&th=1

But I am told you can also use the ears from receptacle.
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#18
(01-13-2023, 05:17 PM)Don_M Wrote: I am a bit puzzled by your results. First, just to make sure we are talking the same nomenclature – I assume when you refer to “pair 1 white” that is reference to the white – or neutral of the black and white incoming (or supply) pair and that “pair 2” of the outgoing black/white pair. A sketch would be helpful.

First, based on what you are describing it does not sound like the (duplex?) receptacles are/were  properly made up. Both the incoming white (neutral) and black (hot) wires should be bonded in the box with pigtails connected to the receptacle (s) – unless it is the last receptacle on that particular circuit. And of course all the grounds should be bonded thru the box See sketch below. There should always be a (120 vac) voltage reading from either side of the receptacle (see sketch below).

Using your nomenclature and assuming my sketch accurately describes your situation:

1.      pair 1 wht (w1) to pair 2 blk (b2) - 0 volts  as expected – should read 120VAC
2.  pair 1 blk (b1) to pair 2 wht (w2) - 79 volts  unexpected - should read 120VAC
3.  pair 1 black (b1) to pair 2 blk (b2) - 90 volts unexpected - should read 0VAC

FWIW – the 79-volt and 90-volt readings are a bit bothersome. It sounds like the neutral potentially might be “floating and not properly bonded to ground at the sub-panel.

I like to wire as you describe also.  Pigtails make it so much easier to get a new recept into the box, less wires to stuff in there.  But, it is rare to find that in residential construction  in my area.   Most use the 4 screws on the recept to connect in/out cables.  Works, passes inspection, but much harder to install, IMO.
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#19
(01-14-2023, 07:27 AM)taxman Wrote: They should be shimmied. 
I like these from amazon

https://smile.amazon.com/gp/product/B00A...=UTF8&th=1

But I am told you can also use the ears from receptacle.

Plus one.  Cheap AND effective.


Yes
Mark Singleton

Bene vivendo est optimum vindictae


The Laws of Physics do not care about your Politics   -  Me
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#20
(01-14-2023, 10:17 AM)kencombs Wrote: I like to wire as you describe also.  Pigtails make it so much easier to get a new recept into the box, less wires to stuff in there.  But, it is rare to find that in residential construction  in my area.   Most use the 4 screws on the recept to connect in/out cables.  Works, passes inspection, but much harder to install, IMO.

Now we are getting into a whole discussion area re: wiring! My understanding is there is no specific code requirement for pigtails – HOWEVER, the code does require that the continuity of grounded connectors (which includes the neutral) not be dependent on device/fixture connections. So at a minimum, the ground and neutral would need to be “pigtailed”. And for good reason – you would not want the integrity/continuity of the grounded system to be compromised by the removal of a device

I am on the local H4H electrical “team” and do a lot of house wiring. For new construction, we always pigtail both hot and neutral because it is easier to “ring out” (i.e., check continuity) after the rough installation, but before all the  sheetrock goes up. We also use mostly (although not exclusively) Wago wire connectors instead of wire nuts. Personally I think they are a more reliable connection and because we also have a number of volunteers (with various skill levels) we find the Wago is an easier connection v. wire nuts for the volunteers.

https://www.wago.com/us/discover-wire-an...connectors
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