Generator use, ground rod.

[Windy in Kansas]

As sort of a follow up to the generator use mention---

How many of you follow the generator directions and drive in a ground rod to hook to? I think about every one of them tells to do this.

[unregistered41671]

Originally Posted by Windy in Kansas

As sort of a follow up to the generator use mention---

How many of you follow the generator directions and drive in a ground rod to hook to? I think about every one of them tells to do this.

I am guilty, that is what I do......... think about it. Then I start the gen up and plug what I want to run in. I am sure it would be much safer if I used a ground.

[ace admirer]

use the local ground only when using the generator as a stand alone,,,do not use ground when feeding house, use the houses ground.

[rancher1913]

if your running tools it could be a life saver one day. if your powering your house it will already have the ground in place and you could get a difference of potential with two separate grounds

[Bearfootfarm]

I have mine on an all metal trailer that is in contact with the ground (and not just through the tires)

[salmonslayer]

I had asked the same question earlier this year and the answers were all over the map. Since then I have talked to probably 20 different people locally and though some of them say you should use one all of them admitted they dont (and this includes several contractors).

I have a transfer switch that allows me to plug into the house for power outages and I correctly (it seems) assumed the house ground would suffice for that but for stand alone use how do you set up your grounding rod? I mean I see them being used on concrete, asphalt, boats, docks, etc with no ground but if I just want to be safe how do you do it? My generator manual says to use one and gives zero instructions on how...

Here is what I found on the issue and to my uneducated mind it looks like they dont need to be grounded:

National Electrical Code (NEC) 250.34 Generators-Portable and Vehicle-Mounted
(A) Portable Generators. The frame of a portable generator is not required to be grounded to the earth if:

(1) The generator only supplies equipment or cord-and-plug-connected equipment through receptacles mounted on the generator, or both, and

(2) The metal parts of generator and the grounding terminals of the receptacles are bonded to the generator frame.

and OSHA directs (29 CFR 1926.404(f)(3)(i)) that the frame of a portable generator need not be grounded (connected to earth) and that the frame may serve as the ground (in place of the earth).

[Bearfootfarm]

My generator manual says to use one and gives zero instructions on how.

Mine has a screw in the frame for attaching a ground wire, but I figure since it's on a metal trailer, and I have metal stands to keep the trailer level, there's no need for a seperate rod

[Harry Chickpea]

What you are describing is called a "floating ground." They occur in electronics, especially old electronics, and may or may not be a problem.

Your electricity that comes to the house has an inherent ground, because of the neutral center tap of the pig on the pole needing to be at ground potential.

With a 12 volt battery and inverter, or a small generator powering tools, the leads can be completely isolated from ground and "floating" in voltage above ground potential, which really doesn't matter much safetywise, since there is NO RETURN PATH. You can hold one lead and stand in a pool of water and nothing will happen if the system is "floating."

When you hook into a house system, BOOM, the neutral (white) connects to an earth ground at the entrance grounding rod. You DON'T want to stand in a pool of water and hold a lead then, because there IS a return path.

So why ground an otherwise floating ground generator? Radio interference. Generators are by definition a source of 60 hertz energy. They also can have noisy brushes, harmonics of the 60 hertz signal, and have cords act as antennas. Slap a ground on the case and most of that goes away.

(In electronics a floating ground happens when the chassis of a radio or other bit of equipment is somehow not at the household ground potential. It can cause all sorts of strange problems.)

[salmonslayer]

Originally Posted by Harry Chickpea

What you are describing is called a "floating ground." They occur in electronics, especially old electronics, and may or may not be a problem.

Your electricity that comes to the house has an inherent ground, because of the neutral center tap of the pig on the pole needing to be at ground potential.

With a 12 volt battery and inverter, or a small generator powering tools, the leads can be completely isolated from ground and "floating" in voltage above ground potential, which really doesn't matter much safetywise, since there is NO RETURN PATH. You can hold one lead and stand in a pool of water and nothing will happen if the system is "floating."

When you hook into a house system, BOOM, the neutral (white) connects to an earth ground at the entrance grounding rod. You DON'T want to stand in a pool of water and hold a lead then, because there IS a return path.

So why ground an otherwise floating ground generator? Radio interference. Generators are by definition a source of 60 hertz energy. They also can have noisy brushes, harmonics of the 60 hertz signal, and have cords act as antennas. Slap a ground on the case and most of that goes away.

(In electronics a floating ground happens when the chassis of a radio or other bit of equipment is somehow not at the household ground potential. It can cause all sorts of strange problems.)

That makes sense Harry so in effect, a grounding rod attached to a portable generator that is just powering power tools would actually be more dangerous correct? And other than protecting from lightening or your radio interference I cant see why you would even do it.

[ace admirer]

hhhmmm i'm going to disagree....all stray currents will try to neutralize themselves to earth ground. floating neutral is dangerous unless low voltage

[Harry Chickpea]

"That makes sense Harry so in effect, a grounding rod attached to a portable generator that is just powering power tools would actually be more dangerous correct? And other than protecting from lightening or your radio interference I cant see why you would even do it. "

Slightly more dangerous. RFI can be a big issue around blasting sites or if you are using AM communications.

ace, guess we'll just have to disagree on that one. If you can find info to the contrary online, I'd be interested in looking at it.

[OkieDavid]

When I hook to the house, I ground to the house ground rod. When I am just powering hand tools I don't

[KC8QVO]

It might be a good idea to use a ground rod. I was working on a radio set up in a trailer that was running off a generator. The power was grounded to the trailer frame. I was working on the antenna coax cables, that were in turn grounded to the trailer through the bulkhead connectors. I ended up bridging the ground path for the generator to ground when I went to hook in the cables outside on the bottom of the trailer box.

Speaking of ground rods.... pound them in and connect to them WITH THE GENERATOR OFF too Otherwise you'll end up zapping yourself pretty good.

[Windy in Kansas]

Speaking of ground rods---do you pound yours in? Otherwise how do you install them?

An electrical company worker educated me decades ago on an easy way for our area. I expect soils would be different and this might vary.

#1 You dig a small hole a few inches deep (3-6") where you want to install the rod and then fill it with water. Refill as needed.

#2 You drive the rod in 3-4 inches but not so far that you can pull it back out easily.

#3 You then push and pull the rod up and down each time allowing water into the hole the rod has just left when withdrawn.

It is amazing how well this works. As the rod is lifted the sediment clings to the rod and as it goes down again that sediment is washed off and the rod goes deeper. This is a much much faster installation in most instances and with less effort than driving one in.

It is much like the old driving rigs for water wells and oil wells.