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Table lamp power rating

by deejay220989
Tags: lamp, power, rating, table
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deejay220989
#1
Jul3-12, 08:38 AM
P: 5
Hi,

I have a table lamp, ratings:
110 - 240V
50 - 60 Hz
Max 60W

The plug is fitted with 13A fuse.

Now, the thing is, how did they calculate the max 60W out from these ratings? According to P = V * I, my max power should be a very large value.

So can I fix a 100W bulb to this table lamp? Why did they limit the power?

Thanks!
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NascentOxygen
#2
Jul3-12, 09:21 AM
HW Helper
Thanks
P: 5,334
Generally they limit the power for safety considerations, either the bulb or shade will get too hot for even brief contact with wandering fingers, or the shade material (or curtains brushing it) or the electrical fittings or electrical wire housed inside it will degrade or melt or risk catching fire.

If the label states max 60W, then no, you cannot safely run a 100W incandescent. For similar brightness, you could consider a 25W CFL.
wirenut
#3
Jul3-12, 09:21 PM
PF Gold
P: 28
The 60 watt rating is usually because the heat generated by the lamp wont quickly degrade the socket material (usually plastic or bakelite). Even with a 60 watt lamp, the socket will degrade over time. Anything higher will cause the socket to melt or become brittle, and the contact for the center of the lamp base to lose its "spring", causing the socket to start losing contact, intermittently at first, and then completely. A fixture rated for over 60 watts has a ceramic socket. You can have the socket replaced at a lighting repair store with a higher rated one. The wiring in the area of the socket is usually rated for 105 degrees c or higher, so that shouldn't be a concern, but CHECK that to be sure as most fixtures are made outside the US, and even though there is a ul sticker, its always better to be safe than sorry. If you choose to have the socket replaced, they can also ensure the wiring will handle the added heat. The cfl suggestion is a good one, but some ppl don't like the "warm up" time on the larger wattage one. I have a lamp on my workbench that has a 68 watt cfl (yes it has a ceramic socket) that has a 300 watt (incand) equivalency. The fuse is to satisfy the NEC and UL limiting a 15 amp plug to approx 80 % if it will be in use for more than 3hrs at a time, allowing the next higher standard size fuse. Sorry about the length of this post.


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