Does 120/60 meant 60 watts is the limit, or the recommendation?

Buying bulbs for a bedroom ceiling light fixture and trying to understand if 120/60 means 60 watts is the best bulb to use, or the maximum-power-permitted limit for the bulb (in other words, something like 45 watts would be just as fine and in fact safer)?

My understanding is that is a maximum wattage. My assumption is that for light fixtures, it has more to do with heat dissipation from incandescent light bulbs, which use most of the wattage to emit heat, not light. But it may be the current capacity of the wiring, too. I just can’t see wiring being so borderline that a few extra milliamps of current causing breakdown, compared to the heat issue.

I’m nearly sure it’s the limit.

Is this still an issue? I assume you’re getting LED or compact fluorescents, and their wattage will be much, much lower. Can you even buy general purpose 60 watt lightbulbs?

If I saw “120/60”, I would assume that meant 120V and 60Hz power. If it were incandescent, frequency wouldn’t matter, but I don’t know if LEDs are frequency specific.

As opposed to 50Hz power elsewhere in the world.

That’s a fair point. In most usages, that would indeed be voltage/frequency. But OTOH, I’ve never seen a light fixture that cared about line frequency.

Me neither, but I had seen it on ceiling fan fixtures, which would be moot too, since motors would run on either 50 or 60Hz just fine–albeit at slightly different speeds.

Do LEDs need frequency criteria?

I think it’s a bright question.

Not easily I should think. Quite likely special order only.

I’m waiting for the day fixtures are explicitly designed only for LED or CFL heat levels and labeled accordingly.

I have seen labels on light fixtures that are more explicit, saying something like “MAX 60W BULB”.

You are going to have a long wait.
Fixtures that are designed for LEDs won’t have replaceable lamps - they won’t need them, since LEDs (if made well) have a nearly unlimited life.

LEDs have a switch mode power supply, they shouldn’t really care about frequency.

Yeah, 60 watts (incandescent) would be the max allowed for that fixture because of the heat generated. As someone said, LEDs don’t have that problem, so you can pretty much ignore that rating and go with a higher lumen output bulb.

LEDs don’t have as much of a heat problem as incandescents, but it is still there.

Yeah, I’ve had LEDs that died early and only then did I notice that they weren’t for use in enclosed fixtures.

Note, though, that that’s a problem for the LED. I doubt it’s a problem for the fixture – a 4 or 6 watt LED is going to generate much, much less heat than a 60 watt bulb.

That’s a good point. Even if they’re not sealed fixtures, if they have replaceable elements they shouldn’t be backwards compatible with incandescent bulbs without being able to tolerate incandescent heat output. Otherwise, some dim bulb (heh) will ignore the warning label and stick a 60-watt incandescent into a fixture not really designed for it and burn down their house and sue everyone involved.

I have seen a high output LED get so hot while running that it melted the solder holding it to the board and fell off. Heat can definitely be an issue with LEDs

As the page below says, the rating given is the maximum intended for the bulb, and running it higher can lead to “overlamping” – not just overheating, but potential damage to the lamp

I’ll point out that there’s another good reason not to run your lamp at higher than the stated rating – you severely shorten the lifetime. Incandescent bulbs have a lifetime that varies approximately as the TWELFTH power of the voltage or current. Running it only a little over severely shortens the lifetime, while running it lower can dramatically increase the life. Of course, you won’t get as much light out, so it’;s a compromise situation. But this is a reason you hear about light bulbs that run for a century or more – they’re run at extremely low wattage.

Centennial Light - Wikipedia.

Not quite so dramatic, but you can try this at home, folks. Turn on the flashlight mode on your phone LED for a while. Put a finger on it.

Once I had a phone get moisture between the outer glass and the lens or CCD, leaving a mist on it. Turning on the LED dried it out.

This – the 120/60 almost certainly refers to the input voltage/frequency. If there’s a maximum recommended wattage, it will be listed either elsewhere on that label or another label.

So…to help clarify my befuddled brain, is it “erring on the side of safety” to use a lower-watt bulb than the watt-number listed as the max of a light fixture, or is that the wrong way to think about things?

The maximum wattage is OK. The manufacturer has already incorporated a safety margin.

Gotcha. I was wondering if a defective light bulb that drew, say, 61 watts instead of the 60 permitted, might be doing a slow-burn-overheating on the wiring. Guess not. (I had thought that becuase my 60-watt bulb was mysteriously going dark despite the light fixture saying it accomodated 60 watts)