DIYbanter - View Single Post - Plan for Basement Electrical Outlets

In oups.com,
wrote:
What do you mean when you say: "Be sure to pigtail out when you
land the outlets." ?

I'm looking at a wiring diagram in my DIY book and I think I see what
you're talking about. But, what's the purpose of the pigtails? They
don't look like they perform any function..

Instead of "daisy chaining" the outlet with the supply going to one screw
and the downstream loand going to the other, you connect the supply, load,
and a small "pigtail" wire together with a wirenut and then wire the pigtail
to a screw on the outlet.

This is especially important for the neutral on a 3 wire "Edison" type
circuit where you have 2 hots and a netrual e.g., 12-3, in the box. In this
case you really have 2 circuits (opposite phases, usually black and red
sharing the same white netural wire. The reason this works is because the
worst case is one circuit (say, the red wire) is fully loaded and the other
one (back wire) is unused. Then you have the same current in the white wire
as the red one which is OK. As you begin to add load to the black wire, the
opposing phase current in the white wire actually cancels out the other and
you have less current in the neutral (white) wire. If both hot wires carried
exactly the same load, there would be NO current in the neutral.

If one of the outlets is removed or fails or a connection comes loose, and
the neutral is not pigtailed, the downstream outlets will suddenly have 240v
across them and be wired in series. Light bulbs turn blue and go pop; other
devices fail in more spectacular ways.

Originally, our house not only had several of these circuits with no
pigtails, but the neutral wires were backstabbed into the outlets. My skin
crawls just thinking about it. It's all been converted now.
--
Jim
"Remember, an amateur built the Ark; professionals built the Titanic."