checking voltage at the luminaire

[Paul]

This would depend on the wattage of the lamp, the wire size going to the lamp, and the length of the wire going to the lamp. You can either use the voltage drop formula to figure out what the voltage would be or you can use that CAST tool to take your voltage reading at the lamp.

[INTEGRA Works]

Originally Posted by Mike M

Okay; nobody seems to comprehend, so let me go back to the question with some actual in-the-field notes from an install today.

I was around 130 feet (it may have been more, would have to go look). Using 10 gauge wire. Five fixtures: (4) x 35, (1) 10. Soldered splice at hub. 15v tap.

(1) At one of the fixtures, I had a reading of 12.7 with the bulb not installed.

(2) Then, I used the Cast tool with no bulb, and got 12.6.

(3) Next, I used the tool as intended by Cast, with the lead end in the fixture socket, a 35 w bulb attached at one socket from the split, and my meter connected to the other socket from the split. (the instrument has two prongs for the fixture, and two wires that split from it with a socket on each). The reading was 11.1 volts with the lamp on.

Which is the reading that gives me an accurate voltage reading, of which I should aim for optimal range (e.g., 10.7 - 11.3).

Thanks,

Mike M

Mike, the answer to your question is #3.

Regards.

[Mike M]

Ah yes. I finally realized the error of my ways. Although I plan/estimate my taps and wire gauge based on voltage drop formulas, in the field I've been checking voltage at the hubs, without regard to fixtures being lamped! DUH!

Thanks everyone for your patience with this green illuminator.

[Illuminator]

The only "stupid" question will be the one that you don't ask. We all had this same question at one point in our careers.