A friend wants to run low voltage wiring for his landscaping, but also wants
to run some feeds for larger lights elsewhere in the yard. He only wants to
punch one hole in his basement wall and was wondering if he could run the
12v wires from the transformer in the same conduit he uses to run a 120v
feed for his other lights. I tried looking in the 2005 NEC, but it led me to
other questions. In 300.3(C)(1) it says that the cables can be run in the
same enclosure as long as the insulation of the lower voltage circuit was
rated for the voltage of the higher voltage circuit. Then it says unless
it's a class 2 or class 3 device see 725.55. What would the class rating of
the low voltage lighting be?
You can't run them in the same pipe or box unless they are both cables
(not individual conductors). Then you have to split them out before
you crack into the 120v cable. UF is really the only 120v cable you
could use. If he has a direct burial low voltage cable he can sleeve
both through the wall in one pipe, then split them out in the same
trench. You just can't keep them together in a box where he is making
It is permissible under certain conditions, but it is not a good idea. You
don't want those wires getting crossed. I certainly wouldn't advise a
weekend electrician to do it that way. They make enough mistakes as it is.
Mixing voltages is asking for trouble with a DIYer. If he rents a rotary
hammer from Home Depot, making a hole in the basement wall won't be a
I can never understand people who get all concerned about making a
hole in their home. guess what? in building the home LOTS of holes
were made everywhere, but most arent visible, covered by other
geez 5 minutes and a cheap hammerdrill from harbor freight and your in
business, done neatly who cares?
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