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I will be replacing a light fixture that had a switch built in and was operated independently from any wall switch. Rather than limit myself to the very few light fixture options with switches built in, I am buying a standard light fixture and installing a switch with a pull chain in the base. I've already researched how to add a switch into the circuit of a light fixture and it's an extremely simple job.

However, I am a little stuck when it comes to choosing a switch.The ampacity of my circuit is 15 amps. Yet the switch I have (originally intended for a ceiling fan) says it can handle either 3 amps at 250v or 6 amps at 125v. This is the US, so I assume it will be closer to 125v.

The old light fixture is marked with 120VAC, 60Hz, 18W, 0.35Amps. It was a miniature fluorescent fixture with one tube.

The new light fixture isn't marked as clearly, but it is made for two 75W incandescent bulbs (I'll be using LED bulbs) and the bulb sockets are marked with 250V and 660W. It doesn't say the amperage.

Is it safe to assume that the switch from the old fixture would work just as well on the new fixture, and the switch for the ceiling fan, too? What amperage should the switch be rated for?

Edit: I forgot to add that the switch from the old fixture also says 3 amps at 250v or 6 amps at 125 v.

  • 2 incandescent screw-ins = worst case scenario of some putz putting dual 150W incandescent bulbs in there. So 300W / 2.5 amps. It would have been better if you had selected a fixture that's physically incapable of taking incandescents. Those are becoming more the rule and less the exception of late. – Harper Sep 20 '18 at 2:54
  • I have no objection to an LED only fixture, however here is my main problem with the idea: from what I've looked at if the LED component dies there really is no way to replace it. I'm not super enthusiastic about spending money on an expensive light fixture only to have to throw it away just because the LED part died. LED bulbs do die eventually, as one of mine just did today in my kitchen and a few weeks ago at my workplace (it was still flickering while holding it in my hand... Strange!) But perhaps when it comes to an actual light fixture the LED component is more durable? – Tagger Sep 22 '18 at 1:32
  • As always, quality is quality. The solid state LED emitter did not fail, the electronic driver did. If you tore down the bulb and bypassed the driver and put it on a bench DC supply attached to both sides of the emitter, and set the supply to 1ma CC mode, the emitter would light right up again... And you could dial-a-brightness even if it wasn't dimmable before. Cheap LED "bulbs" fail because, given the retail price a quality driver is impossible. One hopes you select bulbless fixtures from better manufacturers. – Harper Sep 22 '18 at 5:44
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It is safe.

If you use 2x75w incandescent bulbs, the current would be 2*75W/120V=1.25A, which is way below 6A. If you use LED bulbs the current will be much smaller than 1.25A.

  • Great! That calculation right there is what I needed. I didn't know how to calculate that on my own. The fact that I have two 75W sockets as compared to the previous 18W fixture, was worrying me a bit. But now it makes much more sense. So the switch will be dealing with much less than the maximum amperage it can handle. I'll mark this solved for now. – Tagger Sep 20 '18 at 1:30
  • I agree but most AHJ require the switch to be rated at the max possible draw , still not a problem here if I read the question correctly.+ – Ed Beal Sep 20 '18 at 1:32
  • So the max possible draw would be... 15A going by the circuit or 1.25A going by the light fixture when using two incandescent bulbs? – Tagger Sep 20 '18 at 1:37
  • Just to recap, the fixture is installed and the switch works great! I didn't have a drill bit or drill to make a hole in the base, so I started it with a nail and then turned increasingly larger screwdrivers in the hole to enlarge it and finally kitchen knives (don't try this at home!). Took a little bit of a toll on my knife blades, but when you're on a tight budget, you make do with what you've got. :) – Tagger Sep 22 '18 at 22:48

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