Earthing for 280 KvA Gen-Set

[Hulk-534]

Hello guys,

I wanted to check about my work site and something which I observed today. I work in a oil storage tank terminal. While a tank was down fir maintenance and I was walking past it, I noticed that the 280 KvA gen-set used by my contractor company was earthed to another tanks earth pit.

I just felt something was not right. Upon researching abit, I realised gen sets should have their own earthing and it should have a resistance level of 5 ohms and below. A tanks resistance level is 10 ohms and below. It has 4 earth pits and each has a resistance if 2.5 ohms.

My question is, by connecting the gen set's earthing cable to one of the tanks earth pit, what can happen? Please advise.

Many thanks,
Hulk@Safety

 

[don_resqcapt19]

How are the loads connected to the generator? If they are cord and plug connected, the NEC does not require a connection to earth.

There is no NEC requirement for any grounding electrode to have a resistance of 5 ohms or less. In fact there really isn't any resistance requirement for a grounding electrode system in the NEC. The closest is the rule that says a single ground rod must have a resistance of 25 ohms or less, but if it doesn't, you simply add a second ground rod and then.

I don't see any safety issue with the connection as described, based one the rules in the NEC.

 

[petersonra]

The use of the word earth pit makes it sound like some kind of foreign installation since they are not real common in US installations. This is a US centric website. There are lots of people here who can tell you what a requirements would be if it was a US installation under the national electrical code, but what code and rules apply in your area might be a different thing.

 

[winnie]

In addition to the comments about the US focus of this website (though everyone is welcomed, most of the expertise is US), this website is heavily focused on building electrical installation requirements.

Earthing requirements for fuel storage and distribution are probably not related to electrical system safety, but rather for static electricity and lightning safety. There are probably also requirements for cathodic protection. The point is that we probably don't have much experience to answer your question...but lots of us will be curious as to what you find out.

-Jon