Electrical Wiring in the Home/Wire size, and switch
QUESTION: I hooked up several spotlights with number 10 wire directly to the fuse box. The breaker is used as the on and off switch. My son now wants the switch in the kitchen so he doesn't have to go down cellar every time to turn them on. I know I can break the wire at any point and run the neutral leg to a single pole switch in the kitchen. Here is my question, can I use a number 14 wire for this or do I have to stick to the number 10. Thanks for your help
ANSWER: Robert Wilber
Philadelphia Licensed Electrician
Philadelphia License # 3516 - 16765
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What is the total wattage of the lamps?
What size breaker protects the conductors to your lights?
Why did you use 10 gauge wire?
Your knowledge is erroneous. It is completely improper and contrary to the National Electrical Code to open the grounded conductor [neutral] and leave the ungrounded conductor [hot] connected and energized. Always switch the hot.
If the circuit is protected by a 15 amp breaker, why would it not be acceptable to use 14 gauge wire, which is rated for 15 amps, for the switch?
You need enough slack to install a box where you want to install the splice for the switch leg.
---------- FOLLOW-UP ----------
QUESTION: Hi, I used a number 10 wire as the lights equaled 3000 watts, using ohms law 3000 divided by the current (120) equals 25 amps which requires a number 10 wire and a 30 amp breaker. I already installed a box where the split could be made at some point, please advise, Thanks
I have a lot of bad news for you.
If these lights are going to be on "continuously" [3 hours or more] then the maximum allowable loading is 80% of the rated ampacity of the conductors. That would be 24 amps for 10 gauge. I know it is only a little bit high, but wrong is wrong.
Then, since your load is that high, your switch leg would have to be 10 gauge.
Then, you would have to have a switch rated for 30 amps.
Now, the bad news.
It is only allowed to use a thirty amp lighting circuit in non-dwelling applications.
This needs to be broken up into two 1500 watt 20-amp circuits.
My suggestion would be to run them through a relay and control the relay from the kitchen. You could even use a latching relay with a 24 volt coil and install a low-voltage switch to control the relay.
Sorry for the bad news. Good Luck.