trader_4 wrote in
:

On Wednesday, July 16, 2014 10:21:20 AM UTC-4, Doug Miller
wrote:
wrote in

:



Am replacing a standard wall outlet with a new USB outlet.

The house is only 7 years old.

The existing outlet uses black, white, red and green wires
but

the new outlet's instructions only specify using black, white

and green.



Question is what to do with the red wire? (note: is live/hot

along with the black)



IMPORTANT: my answer assumes that you are in the U.S. or
Canada. If you're anywhere

else, this advice probably does not apply, and could be
dangerous. In particular, if you're in

the UK, stop reading right here.



If you have red, black, white, and green wires feeding a duplex
receptacle, then the two

outlets in that receptacle are served by different circuits --
or, more precisely, they are

served by opposite sides of what is called a multi-wire branch
circuit, also known as an

Edison circuit (Google those terms for more information).



If the receptacle you are installing has only one 120VAC
outlet, you can't use it here.



You need a duplex receptacle, *AND* you need to break out the
tab between the two

screws on the hot side. For illustration, see

http://electrical.about.com/od/diypr.../ss/wiresplito
utlet_6.htm .



Attach the black wire to one of the hot screws (gold-colored),
and the red wire to the other

hot screw. The white wire goes to either of the silver-colored
screws on the other side of the

receptacle, and the green wire to the green screw.



And of course, turn off the breaker before doing any work.


It doesn't have to be an Edison circuit. More commonly you see
one receptacle that's wired hot all the time (usually black) and
the other receptacle wired to a wall switch (usually red).

Good point --but that doesn't really change anything. He still
needs a duplex receptacle, and he still needs to wire it just as I
described.