lampholders......

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chevyx92

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Why do manufacturers rate the fixture for a max size bulb thats way under the rating of the socket. I've seen numerous fixtures rated MAX 65 WATT yet the lampholder is rated 660 watt. Why is that?
 
My guess is that it has to do with the heat generated by the lamp itself. With a 65 watt bulb, you are looking at just over one half amp. The I^2R losses in the wires will be insignificant. But if you ever grabbed a lamp that just failed after being on for a while, you will know that the bulb itself puts out a lot of heat.

I would also guess that they can't make a socket that is ONLY rated for 65 watts, without it being so flimsy that it would never stand up to normal service. So they just tell us what it can stand, even if it will never be called upon to handle that level of power.
 
The sockets are capable of higher wattage but other factors will limit the wattage. An enclosed light fixture traps the heat in the lens. If the wattage is too high the bulb will throw off tremendous heat and burn up the socket (in time) and blow out the bulbs prematurly. Fixtures with larger glass coverings can usually take higher wattage bulbs.

You beat me too it charlie
 
lampholders

lampholders

Also after many years of over wattage the KT, AC, or NM conductors become brittle and fall apart and may become an area of the often said cause (electrical fire)
 
lowryder88h said:
Also after many years of over wattage the KT, AC, or NM conductors become brittle and fall apart and may become an area of the often said cause (electrical fire)
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I don't buy that one bit. You mean to say that a 100 watt bulb vs a 65 watt bulb in a fixture supplied with 12/2 NM will become brittle when your not even talking about an amp!??!!
 
chevyx92 said:
I don't buy that one bit. You mean to say that a 100 watt bulb vs a 65 watt bulb in a fixture supplied with 12/2 NM will become brittle when your not even talking about an amp!??!!
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I'll buy some of it. If it is the old nm etc 60 degree wire it will get brittle over time. I have seen it, but I doubt it would cause fires-- short out--yes, hurt someone--yes. By the way what does it cost to buy part of it?
 
Dennis Alwon said:
I'll buy some of it. If it is the old nm etc 60 degree wire it will get brittle over time. I have seen it, but I doubt it would cause fires-- short out--yes, hurt someone--yes. By the way what does it cost to buy part of it?
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If the wire is rated for anything it can handle an amp!!! 65 watt or 100, it's not an amp. I don't know of any wire that can't handle that. Do you?
 
chevyx92 said:
If the wire is rated for anything it can handle an amp!!! 65 watt or 100, it's not an amp. I don't know of any wire that can't handle that. Do you?
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I believe it is a matter of trapping the heat inside. Thing of it this way, a 100 watt bulb is almost twice the size of a 60 watt bulb. If you put that in a small enclosed fixture the heat will be significant.
 
If you go to any old house with the knob and tubing or AC cable, etc you will see that the wires are frayed and dried out. The fixtures are not big enough to take more than a 100 watt bulb--- perhaps the 60 watt bulbs would have done the same I can't answer that honestly because I don't know.
 
Dennis Alwon said:
I believe it is a matter of trapping the heat inside. Thing of it this way, a 100 watt bulb is almost twice the size of a 60 watt bulb. If you put that in a small enclosed fixture the heat will be significant.
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But you still miss the point. If a lampholder is rated 660 watt and fixture max is 65 watt, your telling me that if I put in a 100 watt bulb the wires will become brittle and cause a fire? I don't tend to believe that. Because on the other hand if you have a lampholder rated 660 watt in a fixture with a max of 100 watt bulb it's no difference. Considering they are fed from same size circuit and wire.
 
chevyx92 said:
But you still miss the point. If a lampholder is rated 660 watt and fixture max is 65 watt, your telling me that if I put in a 100 watt bulb the wires will become brittle and cause a fire? I don't tend to believe that. Because on the other hand if you have a lampholder rated 660 watt in a fixture with a max of 100 watt bulb it's no difference. Considering they are fed from same size circuit and wire.
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A fixture that is rated 100 watt will have a larger enclosure in order to allow the heat to dissipate. Check out a fixture rated for 60 watt and one that is rated 100 watt. The lens or glass is larger. I am talking about enclosed fixtures not recessed cans where the bulb can breath.
 
Dennis Alwon said:
A fixture that is rated 100 watt will have a larger enclosure in order to allow the heat to dissipate. Check out a fixture rated for 60 watt and one that is rated 100 watt. The lens or glass is larger. I am talking about enclosed fixtures not recessed cans where the bulb can breath.
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So tell me about jelly jar fixtures then. They have very little room in them.
 
chevyx92 said:
So tell me about jelly jar fixtures then. They have very little room in them.
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And what are they rated--- I have only seen 60 watt on them . I am sure they make larger ones. Also they are not ceiling mounted fixtures. Heat rises-- jelly jars are 90 degreee to the wires. Have I convinced you yet.
 
Dennis Alwon said:
And what are they rated--- I have only seen 60 watt on them . I am sure they make larger ones. Also they are not ceiling mounted fixtures. Heat rises-- jelly jars are 90 degreee to the wires. Have I convinced you yet.
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I've seen some rated 100 watt max as well as 60. And who said jelly jars are 90 degree to the wires????? You've never seen a jelly jar on the ceiling???
 
chevyx92 said:
I've seen some rated 100 watt max as well as 60. And who said jelly jars are 90 degree to the wires????? You've never seen a jelly jar on the ceiling???
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I realized when i wrote that that I was wrong. I stand corrected on the dam jelly jars but I am certain on the heat buildup and wire damage. Why one fixture is rated higher or lower I am not sure. But the op was why the socket was rated 660 and that was nicely answered by post #2 Charlie. I was just trying to explain what I know through my own experience-- you don't have to buy it if you don't want. If you put a bulb to large for the fixture I will guarantee you that it won't burn very long-- a week or so-- why is that ?? Heat,that's why.
 
Dennis Alwon said:
I realized when i wrote that that I was wrong. I stand corrected on the dam jelly jars but I am certain on the heat buildup and wire damage. Why one fixture is rated higher or lower I am not sure. But the op was why the socket was rated 660 and that was nicely answered by post #2 Charlie. I was just trying to explain what I know through my own experience-- you don't have to buy it if you don't want. If you put a bulb to large for the fixture I will guarantee you that it won't burn very long-- a week or so-- why is that ?? Heat,that's why.
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Well we have 2 different expierences with this. All I'm saying is if the wire is rated and lampholder is rated well over it's capacity then I see no harm in a few extra watts! I'm not saying that this is a common practice just theoretically. You mean to tell me you have never swapped out a 65 watt for 100 watt bulb before??
 
chevyx92 said:
Why do manufacturers rate the fixture for a max size bulb thats way under the rating of the socket. I've seen numerous fixtures rated MAX 65 WATT yet the lampholder is rated 660 watt. Why is that?
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Because the socket itself is a component, whereas the luminaire is an assembly. The rating of the assembly must be observed in installation and use.

chevyx92 said:
Well we have 2 different expierences with this. All I'm saying is if the wire is rated and lampholder is rated well over it's capacity then I see no harm in a few extra watts! I'm not saying that this is a common practice just theoretically. You mean to tell me you have never swapped out a 65 watt for 100 watt bulb before??
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How about an experiment of your own: install a recessed light somewhere in your home and install a 150w bulb in it, and let us know what your findings are.


Hint: if the bulb cycles due to the over-heat limit-switch in the luminaire, consider yourself fortunate that you didn't need to break out a fire extinguisher.
 
LarryFine said:
Because the socket itself is a component, whereas the luminaire is an assembly. The rating of the assembly must be observed in installation and use.



How about an experiment of your own: install a recessed light somewhere in your home and install a 150w bulb in it, and let us know what your findings are.


Hint: if the bulb cycles due to the over-heat limit-switch in the luminaire, consider yourself fortunate that you didn't need to break out a fire extinguisher.
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Have a 100 watt been burning for awhile now. No problems.
In fact socket is rated 660 watts. I guess you miss the point as well. What's the difference of having 2 fixtures both rated with sockets rated 660 watts. One fixtures max is 100 watt and the other is 65 watt. What's the harm in installing a 100 watt in the 65 watt fixture? The wire and socket are rated for it.
 
chevyx92 said:
What's the harm in installing a 100 watt in the 65 watt fixture? The wire and socket are rated for it.
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Because a luminaire is made up of more than just the socket and the wire. There's also the enclosure, the trim or lens, the installation itself, surrounding insulation, etc., all of which contribute to heat build-up and dissipation.

Heat damage is (hopefully) a long-term event. Of course, installing a 100-watt bulb in a 660-watt socket will work. It will even work for a while. But if the heat gained builds faster than it dissipates, there eventually will be damage. (Want brightness? Use CFL's.)

It is both the manufacturers' and our responsibility to make sure that damage is constrained to just the fixture itself. They've done their part by testing and rating each fixture or fixture/trim combination, and it's ours to install within those specs.

You can, of course, do as you see fit.


"But you can't hold a whole fraternity responsible for the behavior of a few, sick twisted individuals. For if you do, then shouldn't we blame the whole fraternity system? And if the whole fraternity system is guilty, then isn't this an indictment of our educational institutions in general? I put it to you, Greg - isn't this an indictment of our entire American society? Well, you can do whatever you want to us, but we're not going to sit here and listen to you badmouth the United States of America. Gentlemen!" ~ Otter ("Take it easy, I'm pre-law." "I thought you were pre-med." "What's the difference?")~ Animal House
 
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