Have a customer that said he has had to replace the 300 watt Pool Light Bulb within a month a couple of times.
The socket is clean, Secondary is wired to the 12 Volt Tap.
No loose Neutral, and other lights on same circuit do not blow, Voltage is always good when testing. Any Ideas?
I about half tempted to relocate the Transformer to increase the length of the Low voltage line, and reduce the length of the High Voltage line, to reduce the voltage the Bulb sees.
Transformer had been replaced and is currently about 6' away from the Bulb.

Just some stab in the dark questions:

Wet niche or Dry Niche? Not that it matters.

12 Volt lamp?

Measured 12 volt at transformer?

I doubt it, but any chance of vibration at the lamp, socket, fixture?

Instead of redcuing voltage at lamp by increasing voltage drop of wire, any chance of finding a lamp rated higher voltage than supply?

This transformer supplies more than this one fixture?

Yeah, I was hoping to find a 13 Volt? BUlb, currently looking into LED, But they are Expensive. They are Nice.
It was 12 Volts at XFMR under load.

Got the make and model number of the lamp?

Is this similar?

300PAR56/WFL/12V - INDUSTRIAL GRADE

That's similar, and would work but needs the R 19 threads.
Its Dry.

Sorry now you got me, what is R 19 threads?

Vibration, stress, bad lot of bulbs, loose connections and surges are the general killers.

Loose connections could be anywhere. If you can measure across the contacts, it could be ideal.

It looks like R19 is a type, not a base: EiKO 05411EK ML-2100 100W R19 120V E26 Medium Screw Base Frosted 2800K Modeling Photographic Light Bulb - Compatible with Novaton 2100 series, Elinchrom D-lites and Profoto Acute photographic strobes

Do you suspect surges? How about the switch? Want to add a ZNR to eliminate the surges?

The Pool is embedded is solid Coral, Vibration should not be a problem, as well as No Loose connection Found at The Connections.
Bad batch, or Cheap bulbs would be my guess.

I would agree with bad batch, but this assumes the client purchased a case of lamps, and is going through them one after the other.

If the lamps are getting purchased one by one as they burn out, maybe not so much is it a bad batch.

Strat, do you have access to a power quality recording unit. Would be best to record at the fixture terminals, however, if the unit is inaccssible during normal operation, as I would assume, thena t the xfer would be fine,since it is only a few feet away.

You never answered me, does the xfer serve only this lamp, or others?

How many?
Lamp wattage?
Xfer size?

Also, what does the R19 refer to?

Just the 300 Watt bulb on the XFMR. Recording would be nice and was an idea. This can take a month before it blows.
We have small suppliers down here, and salesman can sell them crap, they likely get them at a good price and tell them they are quality?
Would have to double check XFMR wattage, it has 12, 13, and 14 volt Taps. Using the 12 volt.