outdoor Mercury Vapor lamp - starting to fail
 

Hi. We have an old (1970's-ish) outdoor lamp, automatic on/off. I think it's mercury vapor - the label says: USE ONLY MV-175 WATTS, TYPE H39 LAMP, 120V 60Hz AC Max 4.0A ...

It's been working fine for 40 or 50 years, but lately it sometimes fails to turn on, or turns on hours later than is should.
Any ideas why it would fail only intermittently?

First thing to try, would be to replace the daylight sensor.

Thanks Oso954 - Is it fairly simple - do they screw on/off or should I get an electrician? I know enough to turn the breaker off first, but that's about it.

1/2 turn and lift it off.

Excellent - thank you!

Agree, thats what it was with mine also. I replaced mine-easy twist lock for 8 or 10 bucks .Day/night sensor.

How long as the current lamp been in the fixture? MV's do last forever, but they get dimmer and dimmer....If it's been a while, you may want to change the lamp also.

They do last very long time however you still can get MV lamps but not the ballast they are no longer legit due the engery pact.


To OP ., If you want to keep simauir luminaire there is a metal halide verison it should have about the same light level as old school MV but only use about half of the power.

100 W MH is about the same as old 175 watter MV are and count the ballast loss that will add up fast so with MH it will actually about 120 watts or so depending on normal or high power facter ballast while common MV useally run about 225 to 250 watts.

Merci,
Marc