bond bushings

[physis]

Re: bond bushings

Stupid me. I was reading that as an air conditioner.

That made even less sense.

That's a good point, it is the supply side of the MBJ.

Ok, thanks Bob.

 

[bphgravity]

Re: bond bushings

I believe our Chief Moderator makes the best point on this topic.

by don_resqcapt19 on May 15, 2004

This is a part of the code where the CMP seems to think that the electrons know if they are on the line or load side of the service disconnect. Multiple bonding of the grounded conductor is required where a common transformer serves multiple buildings that are also served by a common metal underground water piping system. How is this really any different then a single service feeding multiple buildings? Why is multiple bonding a bad thing on the load side of the service and a good thing on the line side of the service?
Don

 

[physis]

Re: bond bushings

Yeah, I still don't get. It doesn't make a bit of sense.

Edit: CMP 5 went out of their way to make this allowance. What is the benefit of this?

[ March 18, 2005, 01:06 PM: Message edited by: physis ]

 

[shortcircuit2]

Re: bond bushings

Iwire...thankyou for your responce to my question...

A fault on the line side of a service disconnect may not open the primary fuse, and if it doesn't something is going to burn clear.

In the Soares book on grounding (9th edition) on page 81,"Bonding of Service-Conductor Enclosures", they state that the bondings purpose is so enclosures won't become isolated electrically and become a shock hazard. Then in the last sentence they say...

"The bonding also provides a low-impedance path for fault current so the fuse or circuit breaker on the line side of the electric utility transformer will open or operate."

All I was trying to say with the bonding on 1 end of that nipple between the meter can and the panel, is that there could be a fire hazard under certain circumstances, as I have described.

shortcircuit2

 

[physis]

Re: bond bushings

How does 250.142(A) not violate 250.6(A) if there is a metal raceway between the meter socket and service disconnect?

 

[bphgravity]

Re: bond bushings

It does violate 250.6(A) in my opinion. So does unecessary low ground impedance. And so does 250.58 and probable a couple of other things.

The problem is no dead bodies, and fires are happening inside buildings and structures and not at the service. So why would the CMP's change 50 years of grounding methods?

 

[physis]

Re: bond bushings

So why would the CMP's change 50 years of grounding methods?

There doesn't seem to be much hesitation to change a lot of stupider things than that.