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I have added an exhaust fan in bathroom to an existing single light switch that operates one light. I'd like the switch to turn the light and the fan on together. The existing switch has one feed of 14-2. I ran a second new 14-2 from the switch box to the new fan and hooked up to the switch. When switch was on, the light came on but not the fan. When the switch was off the light went off but the fan came on. I'm wondering if I should have run my new wire from the light's wiring to the fan instead of from the light switch?

  • Can you draw a simple diagram showing how you wired it up? – Tester101 Oct 5 '15 at 17:02
  • I'm confused by the quantity of fans, is there one or two? Otherwise, it sounds like you have a single pole, double pole switch... – popdan Oct 5 '15 at 17:14
  • Does the existing switch just have one 14/2 wire in it? If so, it sounds like the power source goes to the light first, and the 14/2 just carries a switched hot loop (so there is no neutral in the box). Since you're running new wire anyway, I'd highly recommend wiring it so you get a neutral in the switch box, and you have the option of separately switching the light and fan (even if you don't do that today). It's basically no extra work (other than one more wire to splice in), and likely just means running a 14/3 wire instead of 14/2. – gregmac Oct 5 '15 at 17:23
  • Thanks all. popdan - one fan and original switch is single pole single switch (willing to upgrade to double pole single switch). gregmac - yes, originally the existing switch just had one 14-2 wire in it and I believe power source does go to light first. So, if I pull my new wire out of the light switch box and instead connect it to the light's wiring, that should send power to the light and the fan when I turn the switch on? I'd like to run both off of one switch, It's a rental property and I don't want to give tenants the option of accidentally not running the fan when the light's on. – Chris777 Oct 5 '15 at 19:07
  • Tester101 - Didn't mean to ignore you. There's some things going on behind the wall that I can't see, I'm afraid a diagram would potentially have misleading info in it as a result. My novice brain just thinks that if I simply run off the light's wiring, that should carry to the fan and all runs off one switch... light comes on - fan comes on. – Chris777 Oct 5 '15 at 19:17
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You should extend the wiring from the light, not the switch. There should be two wires on your light fixture, one grounded (neutral), and one ungrounded (hot) conductor that's controlled by the switch. Extend those wires to the fan, along with a grounding conductor. That will allow the switch to control both the light, and the fan simultaneously.

  • I'll add a proviso: Tester101's answer is fine as long as the fan doesn't need to be disconnectable by a double pole switch. (The fans I have bought have always said so in their instructions; this may be a UK safety thing though and not applicable in the US.) – AndyT Oct 6 '15 at 15:35
  • @Tester101 - pdf link instruction no 12 says that for a specific model "A double pole fused spur having a contact separation of at least 3mm in all poles must be used". Although for the other 4 or 5 models on this set of instructions, this is not required. – AndyT Oct 7 '15 at 8:22
  • If this is a simple 115 volt system then running the wire from your switch is the wrong way of doing it unless the two wire power supply goes into the switch box to use. The answer telling you to extend the power and nutural wires plus ground from the light to the fan is the only way to control the light and fan together, that's a plus for Tester101 – Richard Feb 8 '16 at 2:55

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