I have a high pressure sodium vapor lamp that is going onand off

It's called cycling and its normally the swan song for the lamp. A new one should solve the problem. Lamps shouldn't be overly expensive, depending on the size.

We've recently had the same problem. Light would work then it wouldn't. Light went on and off several times each night for a while. Then, for a couple of weeks, the thing worked perfectly. It started the cycling and after a couple of days it went out. It's been out a couple of weeks now. I'd really like to get it fixed. Just don't know who to call to fix it. Concerned about the cost.

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Moms don't look at things like normal people.
-----DD

At the end of life, high-pressure sodium lamps exhibit a phenomenon known as cycling, which is caused by a loss of sodium in the arc. Sodium is a highly reactive element, and is easily lost by reacting with the arc tube made of aluminum oxide.

As a result, these lamps can be started at a relatively low voltage but as they heat up during operation, the internal gas pressure within the arc tube rises and more and more voltage is required to maintain the arc discharge. As a lamp gets older, the maintaining voltage for the arc eventually rises to exceed the maximum voltage output by the electrical ballast. As the lamp heats to this point, the arc fails and the lamp goes out. Eventually, with the arc extinguished, the lamp cools down again, the gas pressure in the arc tube is reduced, and the ballast can once again cause the arc to strike. The effect of this is that the lamp glows for a while and then goes out, repeatedly.

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Deja Moo; The feeling I've heard this bull before.