Premature lamp death

[Mr Steve]

Hi all,

I have some old 650w fresnels and 575w S4 Jrs in a school that I look after. We're seeing that the lamps in the units are dying very prematurely - ie within a couple of months. The lamps have been fitted without touching the glass. They're connected to a pair of Act 6 Digital dimmers, used for maybe 2-3 hours 5 days a week, if that. Lamps are GE Showbiz T26/T27 or Philips HPL.

Is there something supply related that may be causing the lamps to fail, particularly as this seems widespread across the rig of 20 lanterns?

[themadhippy]

european 230v lamps on a uk 240 v supply?

[adam2]

230 Volt, or worse 220 volt lamps on our supply which is still 240 volts most of the time in most places, and can be 250 volts.

Significant over voltage resulting from a loose or high resistance neutral connection, either within your installation, or in the DNO network.

Poor quality lamps, either unknown brands or fake reputable makes.

Bad luck/faulty batch of lamps.

Secondhand lamps fitted dishonestly by someone who is using the new ones elsewhere.

Damaged lamp holders that are burning the connections on the lamps. Carefully examine a failed lamp for any indication of heat damage to the connections. If any such is found then replace the lamp holders. This is IME a frequently overlooked problem.

 

[Bryson]

I used to get this at my old workplace in Newcastle.  Using 220V lamps on our 252.9V supply was the issue.  I couldn't get the supplier to move the taps as it was technically within tolerance.  Got 240V lamps and it helped, but still we blew them faster than I would have liked.

[sandall]

2 hours ago, adam2 said:

Damaged lamp holders that are burning the connections on the lamps.

 

That was my usual cause of failure in non-theatre spaces, but I've also had over-voltage issues. In one of my regular venues I solved the short lamp-life problem by tweaking the global "top-set" to about 90%. A slightly lower colour-temperature "open-white" & a slight loss of intensity, but neither noticeable in practice. Do your dimmers have a "top-set" option, either global or channel by channel?

[Mr Steve]

Thanks all. I'll meter the voltage. The lamps fitted are all believed to be 'legit' branded lamps, I'd hope, purchased from a variety of resellers at different times. Lamp bases are in good condition as I've checked when doing the replacing.

Dimmer wise, they are Act 6 Digitals, which I don't believe had a top-set option. Their desk is a Strand 100 series, which only has a top-set by putting tape on the master!

[Jivemaster]

I've seen a 50hr lamp blow in 15 minutes simply due to a burnt lampholder burning the contact pins.