My new floor lamp came with a warning label saying it should only be used with a 3-way bulb. What possible danger could there be if you used it with a standard (1-way?) bulb??
None, that I’m aware of. Many, many times I’ve used a standard E26 base bulb in a three-way lamp, and the only problem is that the switch goes On-On-Off-Off instead of On-Off-On-Off.
I have had the “handy man” tell me not to use a high watt bulbs in a socket designed for lower wattage bulbs.
This statement was made in this context:
I live in an apartment, the land lord/apartment manager is responsible for the lights on the outside of the building. Specifically, here, each apartment has a light fixture (controlled by an on/off switch inside the apartment) by their door so that folks can see your apartment number (number is on the door), and see if you are home or not…
But anyway, I handed him a 90-watt bulb (all I had as a spare) to test the socket. Socket tested ok, but then he removed the bulb, and told me to obtain a 60-watt instead. He said the heat from a 90-watt might damage the fixture.
In a three way switch lamp, would sticking in a 90-watt bulb also lead to overheating issues? (Or a greatly shortened bulb life span?)
It might, depending on the wattage rating of the lamp. Usually this is printed on a sticker affixed to the bulb socket or somewhere near it. Most bulb-up fixtures and lamps are able to withstand a higher wattage, because the heat flows freely upward away from the socket and switch assembly. You should always check the wattage rating for your lamp when you buy it, and not install a bulb with a higher wattage than its rated for.
Most three-way bulbs are 30-70-100 watts or 50-100-150 watts. If the fixtures can handle the 100 or 150 watts of a three-way bulb, I don’t see how a 90 watt bulb is going to be a problem.
That’s what I thought too, but it clearly says:
The only thing I can think of is, perhaps there are rare cases where the both electrical contacts of a single-watt bulb extend to where the 3rd contact would be? That might cause a short circuit on a 3-way socket. Seems very unlikely though, and that’s not exactly a “bulb malfunction” either.