Hi All,
I wish to put a heat lamp in my garage to keep the temperature up just a bit on cold nights. I know the outlets will take a few hundred watts say 250W but I am concerned the fixture in the ceiling has a safe limit. Is that correct and is it about 100W? In that case I can just get a proper fixture to hold the heat lamp bulb and not use the built in fixture. Thanks in advance for any advice.
Typical 120v circuits are either 20 amp or 30 am circuits. That means that they will support 20a*120v or about 2400 watts. Similarly, a 30 am circuit will support about 3600 watts. Obviously, you don’t want to overload them so staying within 10-15% of the a wattage is a safe bet.
Most 120v heat lamps are less than 250 watts similar to what you might find in a bathroom. Most floodlight fixtures will easily support 100-150 watts. I suspect that yours is a ceramic fixture which should easily handle your 250 watt heat lamp.
I cannot say for certain without looking at the fixture and testing the circuit, but just guessing, I’d say you’re ok plugging in a heat lamp. I think you can get a 150 watt version, too.
I don’t think I’ve seen many 30A single phase breakers in residential panels. A ‘normal’ outlet is 15A which goes on a 15A or 20A (if there are multiple) circuit.
…with most lighting circuits being 15A
You are right. Most of them are 15 or 20 amps.
Normal outlets are rated at 15 amps. The 20 amp outlets look different than the 15, they have the horizontal blade to the side.
Usually printed on a sticker inside the fixture. Modern fixtures in my experience are typically limited to 60watts per socket. Fixtures made up through the 1990s or so were more typically 100watts per socket. Personally I’m leary of anything over 60 watts in anything not explicitly designated for a heat lamp. Something like this brooder lamp would be my goto for adding a bit of heat to a small weather protected space.
Thanks. My house is older that 90’s so I think 100W is ok in the ceiling fixtures but I examined them. They are ceramic but I see no specs on the outside. I have done 100W in my closets. I can easily just get a plug in lamp rated for higher wattage since the wall sockets are.
Master electrician here. While your 120v receptacle outlets are 15 or 20 amp, you should not load them and the breaker to more than 80% for more than 3 hours (continuous load). The breakers are not designed for continuous loads. If you run them over 80% for extended periods the breakers will eventually heat up and fail. And if you have any kind of a loose connection, epic fail. Typically I put 1500 watt heaters in my garage, 1 per 20 amp circuit I have wired. For heat lamps the rating should be on the lamp socket. Either way, if you’re running over 3 hours don’t put more than 12 amps (1440 watts) on a 15 amp circuit or 16 amps (1920 watts) on a 20 amp circuit.
Also, Most pre-led light fixtures for homes are rated at 60 watts, some at 100. If it’s not marked, be careful exceeding 60 watts. If it’s a ceramic or porcelain keyless fixture like you find in attics and garages there’s a good chance it’s rated for quite a bit more. If it’s one of the cheap plastic ones, probably not. Home Depot has some 600 watt porcelain ones for cheap you can get. But if it’s plastic, don’t push it.