Advice for Lighting with ungrounded circuits

[DMXpro]

Hello all,

In about a week, I will be pricing and renting lighting equipment for an event I have been sub-contracted to run tech for at a local fine-arts college. I work for the college as a utilities/maintenance person. The venue is an old library with no rigging, so I will need T-stands (or whatever else they might be called; just tripods with a crossbar. Likely ETC Smartstands) and shoebox dimmers. The only bottleneck I forsee is the fact that the library is old, so the only outlets close to where I'd like the stands to go are ungrounded NEMA 1-15 receptacles. I have a few ideas on how to proceed, but I'd like advice if one or more are impossible.

1. Use a "cheater plug". I'd solder a stranded [HASHTAG]#12AWG[/HASHTAG] wire to an alligator clip and the tab to provide a more solid connection to ground. No one uses the screw, and it's pretty flimsy anyway.

2. Find grounded outlets (if any) and run cabling to them.

3. Have the electricians on staff install GFCIs (might not happen).

[HASHTAG]#1[/HASHTAG] would be the easiest, and my thoughts are since it's just incandescent lighting, there's no real trouble. However, on the other hand, the dimmer packs might prove dangerous if plugged in backwards, I don't know.

Thoughts?

Thank you!

 

[Scenemaster60]

First of all, you don't need GFCIs, you just need a solid ground.
The biggest question is "how was the space wired initially". If all of the wiring was done in rigid, thin wall or Greenfield conduit it is perfectly acceptable to install grounded receptacles OR use the typical 3-prong adapter. The way to test this is to use either a continuity tester or a voltage tester and see if you get a bright light or full voltage from the hot to the receptacle box. IF you do then all is well. If you get nothing, well then you're going to have to consider other options….

 

[DMXpro]

First of all, you don't need GFCIs, you just need a solid ground.
The biggest question is "how was the space wired initially". If all of the wiring was done in rigid, thin wall or Greenfield conduit it is perfectly acceptable to install grounded receptacles OR use the typical 3-prong adapter. The way to test this is to use either a continuity tester or a voltage tester and see if you get a bright light or full voltage from the hot to the receptacle box. IF you do then all is well. If you get nothing, well then you're going to have to consider other options….

GFCI's are just for safety. I'd be fine with a standard 3-prong outlet. As for the wiring, I'd have to ask, but I'm 85% sure it's greenfield conduit. I work tomorrow, I'll ask what can be done (and if we can trace the circuits so I don't put 8 lekos on one 20A breaker!)

 

[Scenemaster60]

Tracing the circuits is just as essential as a solid ground. Also, determine for certain whether the branch circuits are 15 or 20 amp. That's the difference between 3 and 4 lights per circuit.

 

[Dionysus]

Do what you need to do with ground. Another way to test ground is to do a continuity test between 'neutral' and 'ground' as both are grounded conductors bonded at the service entrance. I typically use both methods when encountering ungrounded receptacles as a double check of the quality of the bond and identified conductor.
If you do have a ground present Id suggest asking them to pay the dirt cheap price of putting in new 3-prong receptacles.
If not using an adapter will do you no good as there is no bond present to tie into (unless you run one).
Shouldn't say this but your option would pretty much be to use the adapter just to plug into the 2-prong receptacle.

If there is NO bond present you SHOULD used a GFCI, as if something does go to ground at any point it will kill the power. This is a standard thing for us electricians to do when there is no way to get a grounded conductor to the receptacle, for safety. Its code compliant. Id still much rather have a bond present, especially with electronics like dimmers.

Of course trace out the circuits, hopefully you find enough close enough. Given the type of construction, chances are you only have one or two circuits around and they will be 15a.
You might have to run back to a utility room (I'd say pretty common for a place like that).

Try and go with lower wattage lamps or fixtures if at all possible to squeeze out as many fixtures as you can from your shoebox dimmers. Or you may only be able to run 2 or 3 per pack. The last thing you want is to be blowing fuses or breakers mid event, and trust me that is when they will likely pop, not when you are testing and setting up.