Re: Grounding ? for PTO generator

Posted by txgrn on August 14, 2005 at 06:25:48 from (209.151.118.86):

In Reply to: Grounding ? for PTO generator posted by jCarroll on August 13, 2005 at 20:19:09:

Your "floating generator" is just that; floating.

Think of it as a battery like powers your tractor. Let's just suppose that instead of 12vdc, the battery was sitting there at 120/240 ac. I know it's not possible, but follow me.

The way you act towards your battery is the same way you would act with your gen (except for the potential being larger).

All the power the battery is delivering (can deliver) is with respect to the tractor frame because that is where you tied your reference (the other terminal of the battery). You can put one hand on the tractor chassis and the other on the earth (ground) and nothing will happed because there is no complete circuit...you only have one line connected....the one your body is making.

To have current flow, hence produce a shock hazard to you, YOU (I mean your body) have to complete some kind of a circuit. Electrons have to leave the gen, go through something, enter your body, leave your body, and go through something else to get back to the source, the neutral (ground; return) on the gen.

So if the gen is isolated sitting there on ruber tires, there is no complete circuit to the earth till you make one. If you grab the power terminal or the ground terminal, with only one hand, and nothing else, you aren't going to get shocked. Period.

Now when you connect your gen to something; say a building, then you need a common point of reference. Since the gen has a gnd, neut, rtn terminal, that is your point of reference.

If you are powering a building for instance, your gen ref terminal must be connected to that building's reference with as big a wire as you are using from the power terminal and preferably as short as possible.....like park the trailer as close to the building's power box as possible. I'd tie to the power box ground, not the wire going to the rod in the earth (ground).

Then, with your generator reference now at earth ground potential, if you stand on the earth (ground) barefooted and grab the 120/ 240 gen output terminal you are dead meat....because the building is grounded (via the grounding rod connected to the power box reference), and you now have completed the circuit and can receive a lethal shock....gen output terminal to your hand, your feet to the ground rod thru the power return back to the ref on the gen....complete circuit...shock hazard.

If what I said is not absolutely clear, ask more questions.

Just be sure your building isn't connected to the utility companies power lines when you do this.

Mark

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