Electrical Ground for a Metal Drum?

Factual Questions
1

Should I ground a metal drum that contains volatile and flammable lacquer thinner? How would I go about doing this safely?

I’m guessing that two medium sized alligator clips soldered to a length of rubber shielded copper wire with one clip on the rim of the drum and one clip on a metal electrical wire casing should do the trick.

Am I just being paranoid? Seems to me I’ve seen this done before.

2

Well, [here](http://jones-wenner.com/glossary/glossary23.htm#fire safe grding) it says:

I noticed several things as scanned pages looking for this. First, there are many pages describing regulations and permits to store drums. I’ll bet that your locality has a few. Second, sites run by fire departments have many tips.

Whether it’s required or not, I think a good idea would be to call your local fire department and ask them to inspect your site for safety before you do this. They will know about any legal requirements like permits as well.

3

Thanks Perderabo.

Stangely, a fire inspection was just done before I arrived. I’m supposing local regulations are lax, but with the info you provided, I should be able to fix something up.

4

You may find it more convenient to drive an earth electrode into the ground near to the tank and use a bonding strap to that.

5

If you do ground to an earth electrode, you must bond that to the building’s ground as well. Potential differences between earth grounded structures can be significant, especially during electrical storms. For the electrode I placed for my satelite antenna, I found a potential difference of 220 mV on a perfectly clear, dry day.

Any metal fences should be bonded together as well.

I can dig up code and/or more info if you so desire.

6

I’m not sure what the code is, but it has always been my understanding that:

  1. There are situations where your ground wire must connect to building ground (which also connects to the center tap of the power line’s step down transformer), and

  2. There are situations where your ground wire must connect to a grounding rod adjacent to the appliance.

Most of the time #1 is true; if you have a ground fault in a device or appliance, the only the way the breaker will blow is if the ground wire has a low impedance path to building ground.

But there are no power cables going to the drum. Therefore, it is my guess that the drum needs to be grounded to prevent buildup of static charge. In that case, I believe grounding to the earth directly around the drum is the proper arrangement. But I could be wrong… does anyone have the code?

7

I should have specified that I’m talking about a metal drum that is stored indoors in a warehouse. I also have poly drums on a pallet and further reading on the subject suggests that depending on the volatility of the substance in them (flash point?) I might have to ground them as well. How would I ground closed poly drums on a pallet? These contain concentrated cleaner that is flammable. Is static electricity really that dangerous?

8

Ask the crew of the Hindenberg about this.

9

Oh the humanity!

10

eunoia, don’t forget to hook up the “far end” of the grounding strap/wire last. If there is a spark when the hook-up is made, you’ll want it to be as far away from those chemicals as possible, in case of leaking vapors. Attatch strap to drum first, then strap to ground. Pretty much as one should do when hooking jumper cables to a dead car.