my three way lamp is suddenly just one way. is this an electrical problem that could be a fire hazard? Why would a lamp just suddenly stop being three way after being plugged and unplugged?

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    Did you try a different bulb? Maybe one of the filaments in the 3 way bulb burnt out. – Johnny Feb 18 '15 at 21:07
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    That seems most likely. Make it an answer and I'll upvote it... – Ecnerwal Feb 18 '15 at 22:16
  • @Johnny not sure if you saw Ecnerwal's suggestion. Ditto – bib Feb 18 '15 at 22:21
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    One way, as in click-on then click-off ... round and round? Exactly as @Johnny said, one of the filaments burnt out (or broke). The way three way bulbs work is it has two filaments, one which is rated say for a 50-100-150 wattage range, there is one filament which is 50 watt and one at 100 watts. The four positions are, 50 by itself, 100 by itself, then 50 & 100 together to make 150, and the fourth position is off. Your 100 watt filament has broken, so only 50 watt filament turns on with every other position. – Pᴀᴜʟsᴛᴇʀ2 Feb 18 '15 at 23:12
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    May be a problem with the power feeding your house. There is a condition known as "floating neutral" that can result in higher than normal voltages at some outlets (and lower than normal at others). If you notice other strange things (especially, eg, lights flickering when you use the toaster or some such) then you should have an electrician check it out. – Hot Licks Feb 19 '15 at 0:22

The most likely explanation is that one of the two filaments inside 3 way bulb burnt out or broke.

If it was already close to burning out before you moved the lamp, the mechanical shock of moving may have broken it the rest of the way -- perhaps it broke completely so you didn't see the characteristic "flash" of a filament burning out when you turned on the lamp for the first time after moving it.

You could test the lamp contacts in the socket with a continuity tester at each switch position to verify that this is the case, but a much easier (and definitive) test would be to replace the bulb with a new 3-way bulb and see if it works.

  • do three way bulbs last less long than regular bulbs? – tallyho Feb 20 '15 at 17:58
  • It's been a long time since I've bought an incandescent bulb, but I don't recall my 3-way bulbs in the past having a particularly short lifetime. The estimated lifetime should be marked on the package. If you use a 3-way LED or CFL, then you should get much more lifetime out of it than with an incandescent... Assuming that you don't have a problem with power surges that might cause any bulb to fail. – Johnny Feb 20 '15 at 18:10

I had this same problem. First I tried a "new" bulb & it did the same thing, so I Johnreplaced the socket, and that didn't fix the problem. I tried the "new" bulb in another lamp and confirmed that it was defective. The 3rd "new" bulb was good and corrected the problem. The bulbs were labeled GE, but "made in China." The lesson I learned is that sockets seldom go bad, as this is the 2nd time I have needlessly replaced one. Hopefully I will remember this before I make this mistake again.

protected by Community Jul 17 '18 at 14:34

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