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JOHN H VAN ALLEN
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Grounding the Chassis of New Generator

01/25/2013 6:08 AM

Hello: I am completing the installation of a 52kW diesel generator. The chassis has a terminal which is supposed to be grounded into the earth using a copper clad steel rod 8 feet long and driven into the soil. We have done this and are now making the connections. A subject has been raised between 2 engineers observing our work and a difference of opinion has risen.

Should the generator chassis ground be connected to the entire site grounding system?

At our site we have the electrical company ground which originates at the pole in the street. We also have a driven rod ground at the service entrance point where the main breaker panel is located and this ground is bonded to the neutral bar. Should we also extend the generator ground over to the service entrance point and bond them all together.

One engineer says yes and another says no. The one who says no claims that he learnt that the generator ground should be isolated from the site ground to avoid creating noise on the neutral.

What are your opinions regarding this?

When I worked for the telephone company developing microwave radio sites in remote locations we were instructed to unite all grounds. We even ground the rebar using brazing techniques before pouring the concrete for the buildings and tied everything to the ground well.

Thanks

John Van Allen
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Pathfinder Tags: grounding generator earthing ground rod ground/neu
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waldig
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#1

Re: Grounding the chassis of new generator

01/25/2013 6:41 AM

You were talking about the chassis of the generator, and yes it should be bonded to a good site ground/earth. Depending on the configuration of the generator, it may have its output connected to the same ground (wye) or not; delta. The chassis is grounded for safety and very likely is not carrying load current ( hopefully). Enjoy, Woody

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PWSlack
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#2

Re: Grounding the Chassis of New Generator

01/25/2013 7:09 AM

Noise on the neutral is a function of non-linear loads and power factors less than unity at the load end. It matters not if the chassis is grounded locally or whether a cable is run to the remote earth rod.

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North of 60
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#3

Re: Grounding the Chassis of New Generator

01/25/2013 12:22 PM

The case must be bonded. How this is done is... dependent upon the transfer switch that connects the generator to your distribution system.

If the transfer switch switches the neutral at the transfer switch, then you are disconnecting your system neutral from your grounding grid and you will need to re-create the grounding system at the generator. To do so, ensure that the neutral from the generator is grounded by its own grounding electrodes that are code compliant for your area. Also... bond the generator case to the neutral. You are then establishing the start of your bonding system at the generator. Ensure that the bonding system is continued to the rest of your distribution system.

If the transfer switch does not switch the neutral at the transfer switch, then you are depending upon your main system grounding gird for the grounding of your system. In this case, you need to ensure that the neutral of your generator is not bonded to the case of the generator. Ensure that the case of the generator is bonded back into your bonding system.

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North of 60
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#4

Re: Grounding the Chassis of New Generator

01/25/2013 12:54 PM

It is important to remember that generators must be setup by times in one of two ways... 1) In conjunction with an established eletrical service from a utility, and 2) Without an established electrical service from a utility.

When you add additional generators and paralleing gear into the mix... it can get complicated.

How these machines get grounded and bonded all depend upon what you are connecting it to.

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HiTekRedNek
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#5

Re: Grounding the Chassis of New Generator

01/26/2013 2:55 AM

Your question involves a lot of explanation, and more information.So, to make a long story short, here is a link that tells you everything you ever wanted to know about separately derived systems, as pertaining to grounding,bonding,etc.

Read,digest,learn.

www.iaei.org/magazine/2009/11/separately-derived-systems/

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TonyS
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#6

Re: Grounding the Chassis of New Generator

01/27/2013 7:20 AM

This would meet UK BS7671 requirements. I don't know about American

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