I just bought a farm and there is an old yard light on a pole that does not work. It had no bulb in it when we moved in so we have no way to tell what to get to replace it. There is a dusk till dawn photocell, that we replaced and tried a metal halide bulb. That didn't work.

It is wired directly to live current from the house and that is controlled in the Excel Energy meter box so we can't shut it off to replace it. We would like to avoid having to call them or an electrician without first having tried everything we can.

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  • Is it actually spliced into the main utility feed between the meter and the house? Or between the utility and the meter? Either way, that is a huge problem because that would mean no overcurrent protection, which normally would be 15A or 20A for a lighting circuit. Oct 13, 2020 at 17:17
  • It's absolutely not clear from what you've said how this light is hooked up. Please provide more details especially what you mean by "...wired directly to live current from the house and that is controlled in the Excel Energy meter box..."
    – jwh20
    Oct 13, 2020 at 17:22
  • i need you to get up there and take photos of absolutely everything you can. Any nameplates inside or out, shots of the transformer and little controller board up there, anything you can give us. There are 3 sizes of each of 4 different lamp types that it could be, so not worth just trying all 12 lol. For what it's worth, if you remove the daylight sensor, that should de-energize most of the fixture guts. Oct 13, 2020 at 17:25
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    It could very well be a power company light and you might be paying a fee for it. Check your bill and call them
    – JACK
    Oct 13, 2020 at 17:35
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    @ Jack & Ed, I have contacted Excel Energy and was told that the pole that the light and that their meter is on is owned by us and therefore we are responsible for the light and they will not service it or the pole it's on. I checked my bill as well as had them check it - no charge for a security light.
    – Amanda
    Oct 13, 2020 at 19:58

1 Answer 1


It is likely a sodium, Na, vapor or older mercury, Hg, vapor lamp. Inside the outer glass housing, there's a second "bulb" of quartz (clear), for Hg or alumina (translucent white), for Na. If you can read writing on the lamp or fixture with binoculars, you can try to buy a replacement lamp ("bulb"); most have Edison sockets and screw in like an ordinary household lamp. However, you'll need to identify the particular lamp type -- ratings vary from 70 watts to over 1,000 watts, and bases vary.

The lamp is not connected directly to the AC mains, but through a ballast, which serves a few purposes:

  • It provides a high voltage (hundreds or thousands of volts) to start an initial glow discharge, which changes to an arc as the lamp heats and the volatile metal evaporates.
  • It limits the current drawn by the lamp in the preheat phase and when operating.
  • It times the preheating and controls the light, often with a separate photocell head.

If the fault is a dead lamp, it is easily replaced. A 70 watt sodium vapor lamp can be found for US$10. Use reasonable safety replacing the lamp, e.g., a lamp-replacement pole, and insulating gloves. However, replacing the ballast is not recommended, if you do not see an obvious way to shut all power at the breaker 9or fuse) box.

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