New genset shocking

[bankruatsteve]

My friend recently purchased a 5 KVA electric start genset (China sounding brand) and first test went good - for 10 min. then it stopped. After trying several times to start and no go, I asked him if they put oil in it. They did but he checked and nothing showing on the dipstick. Turns out a liter needed and then running OK.

BUT, now he says he gets a shock when touching the frame barefoot. The house ground rod is close by so that's easy enough - but I'm thinking there must be something amiss to get a shock from a generator frame. ??

Thoughts?

[Crossy]

Most small gensets are floating, if it's on an insulating material (rubber wheels) the frame can float to about 1/2 mains if not earthed, much like your PC metalwork can.

Sticking an earth on the frame will sort the problem.

[bankruatsteve]

OK. But, I was looking for the 'why'. The frame should be relative zero potential for the genset. So, why, or maybe how, can it 'float' to a different potential relative to ground?

I didn't show up until the lad was hooking up the battery and he didn't seem to know what he was doing (like it took 30 min.). Could cross wiring the bat cause this or would the starter just not work? It just seems like there is something wrong if getting a shock.

And, it's not on wheels. Just the frame on the concrete. (I think)

Edited March 27, 2014 by bankruatsteve

[Crossy]

Capacitive coupling between the windings and the frame may cause it to float up to about 1/2 mains, particularly if the winding is ground referenced somewhere else.

It's quite possible to get a belt off a 12V battery under the right (wrong) circumstances, but hooking it up wrong won't cause the effect you're describing.

Was it just once or does he get a shock every time he touches it? If multiple times I do suggest further investigation.

I am of course assuming he's getting a shock when the genset is running!

How is it hooked in to the house wiring or is it just sitting there biting people? Check how the ground connection to the house wiring is made (if there is one of course).

If everything seems in order hook the frame grounding terminal (it's there for a reason) to the house ground rod.

[kovaltech]

Capacitive coupling between the windings and the frame may cause it to float up to about 1/2 mains, particularly if the winding is ground referenced somewhere else.

It's quite possible to get a belt off a 12V battery under the right (wrong) circumstances, but hooking it up wrong won't cause the effect you're describing.

Was it just once or does he get a shock every time he touches it? If multiple times I do suggest further investigation.

I am of course assuming he's getting a shock when the genset is running!

How is it hooked in to the house wiring or is it just sitting there biting people? Check how the ground connection to the house wiring is made (if there is one of course).

If everything seems in order hook the frame grounding terminal (it's there for a reason) to the house ground rod.

Agree about the capacitive coupling,

any electric generator ought to be grounded as described in the manual,

touching an running generator , not grounded, barefoot ? asking for it, trying to piss on an electric fence ?

Before using any equipment, make sure that you did read , understand and followed the manual...