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I have some outlets that are set up in a split circuit (separate lines for top and bottom). I was going to replace the outlet to update it to a more modern looking one and found that there are 4 power lines coming in. Power in and out and for each circuit (so 4 total black wires and 4 total white wires). It is currently using both the screw and push-in method.

Is this proper wiring? I've never seen both the screws and push-ins used. It's also very tight in the box. Is there a better way to handle this? It seems like pigtails would be better but I feel there isn't enough space.

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    Pedantry: That's technically not in series. Each device has a parallel circuit attachment. – isherwood Sep 3 at 20:50
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    @isherwood Interesting point. I've used those terms interchangeably and didn't realize there was a difference. Thanks for point that out! – AroundPolandTravel Sep 3 at 20:59
  • You could get away with "in a series", but it's still potentially confusing. – isherwood Sep 3 at 21:01
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Pigtail , pigtail , pigtail, and hook up your new receptacle. The back stab (the push in connection is the largest failure point of any wiring method I have ever heard of but “safe” because when they fail they are inside a box. Hook your 3 blacks and a short section of wire together with a wire nut then this shorter wire to the gold screw. Do the same with the white wires and connect the short white to the silver screw and you have eliminated the major possibility of a failure if someone plugs a space heater, or hair dryer with a few other devices going also down stream. Is it legal yes it will pass inspection in many jurisdictions but not all. Is it safe , according to the national electric code, but I have seen smoke damage many times and even plastic box meltdowns but no major fires. But those push in connectors are a major failure point. I like back & side receptacles they can connect up to 4 wires each side but cost a couple of $ more. So pigtail with a wire nuts or get back and side outlets. I’d your boxes are shallow spending a bit more on the receptacle is the only way to go and they last longer as they are a higher grade.

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    What are back & side receptacles? Doing some Googling and it appears to just return that same type of outlets that have the push-in and side screw. Am I missing something? Do they make tamper resistant version of the outlet you are referencing? – AroundPolandTravel Sep 3 at 14:58
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    Yes add the term spec grade back and side, sorry about that I usually mention spec grade versus the cheap builders grade. The spec grade has a clamp plate that allows 2 wires under each screw and is faster than wrapping. I found out not long ago with these each screw can have 3 wires, 1 wrapped and 2 clamped, I thought it was a code violation but Leviton said they were listed for that. Hope that clears things up. Note spec grade receptacles are built to a higher quality standard and will last longer with better connections. – Ed Beal Sep 3 at 15:15
  • Just to verify, is that what you are referring to? Leviton TDR15-W So these are considered more secure than that standard push-in ones on consumer receptacles? Thanks for your help! – AroundPolandTravel Sep 3 at 15:28
  • Absolutely yes these are more secure than backstabs. The push in connectors (backstabs) have a little spring loaded contact making the connection. When a heavy load like a space heater is used sometimes this alone is enough to cause problems but there are usually a few other things when they fail. The clamps are solid and squeeze the wire under the clamp, I don’t think I have ever seen one of these fail with stranded or solid wire. The back stabs have made me tens of thousands over my career (I and many electricians think they should be outlawed). As you can see they cost more but will last. – Ed Beal Sep 3 at 15:38
  • Thank you! This may be the best method for me since I'm still learning about electrical and would allow me to leave the wiring as is and just move it to the new receptacle. – AroundPolandTravel Sep 3 at 16:04
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The connection method

The last guy used the backstabs out of "necessity" (read: it was a "necessity" to use a 60 cent outlet instead of a $2.60 outlet that had screw-to-clamp terminals).

Follow Ed Beal's advice here, but with pigtails, that box will get rather crowded.

The box fill

As for practical fill, Ed Beal covers that very well.

Statutory fill rules are like this: A #14 wire counts for 2.00 cubic inches, a #12 wire counts for 2.25, and a #10 wire counts for 2.50.

  • All cable clamps, together, count as 1 of the largest wire. 2.00 for you.
  • All grounds, together, count as 1 of the largest wire. 2.00.
  • Any "yoke" (that receptacle) counts as 2 of the largest wire attached to it. 4.00.
  • Pigtails are free.
  • Every other wire in the box counts as 1 of its own size. Your eight are 16.00.

Total 24.00 cubic inches. There should be a stamp on the back of that box indicating its cubic inches, 24 is pretty darn big for a 1-gang box.

If the box isn't big enough, get a "surface conduit starter box". This will stand up proud of the wall by an inch or so, but that will give you the needed cubic inches.

Breakers

This is not a multi-wire branch circuit. This is two independent circuits on a single "yoke". Because of this, the two independent circuits must be handle-tied.

A handle-tie must come from the manufacturer of your breakers; you can't use a nail. While you're there, make sure your breakers are correct for your panel because there's no point buying a handle-tie for an alien breaker. If they are the same manufactuerer (Bryant=Cutler Hammer=Eaton), you are all set. Otherwise, they are probably wrong but ask.

Handle-ties are annoyingly difficult to find, and overpriced for being a bit of plastic. As such, some of us recommend using a 2-pole breaker instead - they are very easy to find for modernish panels, and they cost the same as 2 singles without having to pay for a handle-tie also.

The only difference is common trip (both shut off if one is overloaded): a 2-pole breaker guarantees this, a handle-tie does not guarantee it. For this purpose, we only need tied handles to assure common maintenance shutoff.

  • That's interesting on the breaker. I didn't think about that but I don't believe they are handle-tied or a 2-pole breaker. I will need to verify that. They are both in a sub-panel breaker box. Would that make any difference in the need of being handle-tied? – AroundPolandTravel Sep 3 at 15:08
  • @AroundPolandTravel Nope, they need to be tied, period. – Harper - Reinstate Monica Sep 3 at 16:26
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Using push-ins on a split circuit is a recipe for disaster, given the absolute necessity of a reliable neutral connection in this configuration.

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    Welcome, Phil. This doesn't really answer the question. Please take the tour to learn how we're different from a discussion forum. – isherwood Sep 3 at 20:52

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