How many watts for a single socket porcelain ceiling fixture?

[4570Man]

Most of the lights in my house are LEDs. The ones that aren't are a lot less than 300 watt. I save the beautiful 300 watt bulbs in a ceramic fixture usually mounted on an exposed metal box for applications in which I couldn't care less about efficiency.

 

[mbohuntr]

Keep this in mind as well, What is your breaker and circuit wire size? A 14-2 wire is not designed to carry over 15 amps.... and needs to be protected by a 15 amp breaker regardless of what your fixtures will handle. Watts = Volts x Amps, so 120V x 15A = 1800 watts MAX. You also need to find out what else is on the circuit. Most will tell you to run 80% of that max to be safe.. I agree.

Switching to LEDS usually means a large drop in wattage for the same lumens of output. Do not put a dimmer on it unless your lights specifically are rated for it, or.. you will end up with that same pile of smouldering ash...

 

[4570Man]

Don't know why he'd want a dimmer. The idea was more light.

 

[mbohuntr]

Don't know why he'd want a dimmer. The idea was more light.

Might already be in the circuit... I rented a house in AR. that had a dimmer... I got up one morning, started coffee, with the lights dimmed and smelled something burning.... The last occupant had slipped in a couple of LEDs in the can lights....

 

[Larry Caldwell]

In my barn I found some screw-in fixtures with a 12" white reflector, then screwed in a 2-bulb splitter and two 100w equivalent CFLs. One of those every 8 feet made things pretty bright.

 

[teejk]

Heard something about LED's on the radio last week...something about the bulb running cool but the base can get really hot depending on what you buy? Was a home improvement call-in show and maybe it was a caller trying to hawk one brand over another.

 

[mbohuntr]

Heard something about LED's on the radio last week...something about the bulb running cool but the base can get really hot depending on what you buy? Was a home improvement call-in show and maybe it was a caller trying to hawk one brand over another.

LEDs are DC voltage, so several things need to happen in the base of the light... 120 Vac in gets stepped down to some much smaller voltage like 18Vac via a transformer, then it is rectified to DC voltage anywhere between 24 to 5 Vdc depending on the application, and then might get pulsed as around 1Khz 50% duty cycle to save even more power.. so... yes there are places that might get hot. This is stuff I studied 15 years ago, and likely has changed quite a bit since then.

 

[RNeumann]

LEDs are DC voltage, so several things need to happen in the base of the light... 120 Vac in gets stepped down to some much smaller voltage like 18Vac via a transformer, then it is rectified to DC voltage anywhere between 24 to 5 Vdc depending on the application, and then might get pulsed as around 1Khz 50% duty cycle to save even more power.. so... yes there are places that might get hot. This is stuff I studied 15 years ago, and likely has changed quite a bit since then.

Every one I’ve had on an oscilloscope in the last several years is pulsed (duty cycle). And yes they are still all over the map with voltage and frequency.
The statement about the dimmer is correct. Most LEDs don’t dim and the ones that do brag about it and still typically need a special dimmer.
Their isn’t a standard with the LED bulbs and fixtures.

 

[Mace Canute]

Heard something about LED's on the radio last week...something about the bulb running cool but the base can get really hot depending on what you buy? Was a home improvement call-in show and maybe it was a caller trying to hawk one brand over another.

I just checked my computer room lights. I have a dual bulb fixture with Sylvania 6 watt LEDs, 450 lumens each. I can hold my hand on them anywhere but after about 15 - 20 seconds it's too uncomfortable to hold so yeah, quite a bit of heat but way less than the incandescents they replaced.

 

[newbury]

I just checked my computer room lights. I have a dual bulb fixture with Sylvania 6 watt LEDs, 450 lumens each. I can hold my hand on them anywhere but after about 15 - 20 seconds it's too uncomfortable to hold so yeah, quite a bit of heat but way less than the incandescents they replaced.

I don't think it's the heat of the bulb but the heat of the fixture.
But anyways -
Like I wrote I've a fixture w/ 5 sockets that I put 4 of the 100 Watt LED bulbs in. They have been running more than 12 hours.
So I pulled out my trusty HF IR thermometer.
Ambient temp is like 60 degrees F
The porcelain socket is 68 degrees F
The base that 1 light screws into is 104 degrees F
The "covered" bottom half the bulb is about 122 degrees F.