Daisy chain or tails - resistance in receptacles ?


Old 01-12-14, 04:22 AM
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Smile Daisy chain or tails - resistance in receptacles ?

I've seen a few references to the resistance in receptacles, advocating pigtailing both Bl and Wh to supply electricity to each outlet, thus avoiding a daisy-chained series of outlets. I have yet to find a reference to quantify that. Is that resistance really worth the extra trouble? I would like to see numbers and not rely on myth before crowding the heck out of the boxes.
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Old 01-12-14, 06:27 AM
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The resistance is negligible and a non-problem.

Connecting the incoming and continuing wire ends dirctly to each other with a pigtail to the receptacle often makes it easier to stuff the receptacle back into the box, three wires (incl ground) instead of five to manipulate.

The pigtail method is required for shared neutrals, as in multiwire branch circuits, so it is more difficult to unhook the neutral with one of the circuits still live, which presents an extreme hazard.

Otherwise connecting the incoming and continuing wire ends directly to the receptacle is okay.
Old 01-12-14, 07:41 AM
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If a connection at a device were to fail or become loose the downstream devices will still function if pigtailed. You should not have that much resistance in a device.
Old 01-12-14, 07:46 AM
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The only cases that resistance in receptacles can become an issue is with back-stab receptacles. The cheapo receptacles where the wires just 'stab' in the back and are held in place due to the springyness off the brass tab inside.

These tend to loosen over time, causing a poor connection.

But as others have said, properly connected receptacles (using the screw terminals) have practically zero resistance.
Old 01-12-14, 11:03 AM
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duplex outlets - daisy chain or pigtail?

rural SE Louisiana - no inspection required
I've seen mention of resistance in outlets and folks advocate pigtailing to supply each duplex outlet rather than "daisy chain" through the outlet. No one seems to ever quantify the amount of resistance, so I'm curious if anyone has the info. I've also seen statements of here that it "does not matter if you put one hundred outlets (for convenience) on a circuit as long as you are not using but one or two at a time". So which statement is accurate and is pigtailing to the duplex outlets worth the extra crowding in the box? I tried posting this at 5:15 this morning and would like to apologize to the DIY gods if I gave cause not to publish it.
Old 01-12-14, 11:39 AM
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I merged the two threads as two running on the same topic causes a lot of confusion.

Me, personally, as an electrician I add tales for the receptacles. It has nothing to do with resistance..... it's long term reliability.

I've see many electricians run the circuit thru the receptacle's side screws too. That's ok as long as the screws are tightened properly. Back stabbing the wires in the back of the receptacle is not an acceptable way of wiring.
Old 01-13-14, 07:19 AM
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There is no published data on the subject of resistance in daisy chained receptacles because no one has constructed a test bed and gathered data for the purpose of publishing those findings.

It is true that connecting the incoming wire directly to the continuing wire rather than connecting the two to the receptacle results in about half as many joints in the full current path. The fewer the joints, the less likelihood of having a loose connection.

"Push in and it sticks" aka backstab connections have a greater chance of developing a loose connection compared with screw terminals or screw clamp rear connections.

I, like the hypothetical researcher in the first paragraph, have no supporting data but I would conjecture that stuffing the receptacle or switch into the box may put spring loaded stresses on screw terminals leading to loosening of the screw. Massaging the wires to produce some pre-bending as you stuff the receptacle in can relieve any such stresses.

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