Hi there. I've recently purchased a NOS Westinghouse Lifeguard 50 watt mercury vapor lamp off ebay.

After making several attempts to strike an arc with a F40 single lamp rapid start ballast and a 70 watt MH ballast with ignitor removed, I cannot get this lamp to light.

Is there a chance this lamp is a dud? I appears unused and in excellent shape. I really hope I didn't waste my money.

Any way to set with a digital volt/ohm meter?

Thanks.

Sometimes mercury lamps can develop what's called a mercury bridge, where condensed mercury shorts between the main electrode and the starting probe.  I've used a pulse start ballast (in my case, I used low wattage HPS) to start it, and let it run up until it dropped out.  After it went out, I let it sit for about 30 min to cool in a base up position.  That helped insure that when the mercury re-condensed, it didn't do it around the starting probe.

Sometimes mercury lamps can develop what's called a mercury bridge, where condensed mercury shorts between the main electrode and the starting probe.  I've used a pulse start ballast (in my case, I used low wattage HPS) to start it, and let it run up until it dropped out.  After it went out, I let it sit for about 30 min to cool in a base up position.  That helped insure that when the mercury re-condensed, it didn't do it around the starting probe.

Hi there.

Himm, interesting. I have a 50w HPS ballast, would that work? I really hope I can save this bulb!

The 70W MH ballast is quite an overload for this lamp (1A instead of 0.6A when running, nearly 2A vs about 1A at startup), so hope you haven't destroyed the electrodes.
Otherwise the bridge is very likely, mainly if your attempts were base down.
With the HPS ballast make sure the ignitor gets disconnected (disconnect the Neutral to the ballast, so have the main circuit connected not using the HPS ballast wires) just when the lamp ignites, otherwise once the arctube develops some pressure and so increases it's ignition voltage, there becomes quite severe risk of a deadly arc in the outer (that is, why the ignitors have to be deactivated when ballast are used for probe start lamps).

I've tried everything in my power(no pun lol) and I cannot get this lamp to light.

I've tried everything in my power(no pun lol) and I cannot get this lamp to light.

Sorry to hear that. As a last resort, try running it on a PSMH ballast with ignitor connected for a few minutes (don't restrike it, lost a good GE merc that way) and then shut it off. It brought my Westy 100w merc back from the dead and it might for you too.

Quote from: bucket175mv on June 05, 2016, 08:32:41 PM

I've tried everything in my power(no pun lol) and I cannot get this lamp to light.

Sorry to hear that. As a last resort, try running it on a PSMH ballast with ignitor connected for a few minutes (don't restrike it, lost a good GE merc that way) and then shut it off. It brought my Westy 100w merc back from the dead and it might for you too.

Hey thanks for the idea! I've got a 70 MH ballast that I could try just for a brief moment. I really want to be able to use this lamp! I bet the seller on ebay didn't even know that this lamp was inop.