Manhole covers

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alan mcneil

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Massachusetts
In a recent Mike Holt Newsletter the subject of ungrounded manhole covers and the electrocution death of a dog was discussed.
I thought that this was an interesting article and showed it to my boss.
My boss asked me how one would go about grounding or bonding a manhole cover and its metal rim.
Is there a proper procedure on could follow in order to effectively accomplish this task.
 
Re: Manhole covers

Art 250 of the NEC contains the prescriptive rules for grounding and bonding. The type of connection is given in section 250.8 and the type of equpment grounding conductor is in 250.118.

Heres what you need to do:
Bond the metal frame and cover, with a braided bonding jumper, use stainless steel hardware, Kopper Shield, an insulated equipment grounding conductor back the source, to create a low impedance ground fault return path.
Bonding a manhole lid can be hard as the bonding jumper tends to get damaged, a mechnical connection such as a bolt is needed.
 
Re: Manhole covers

The manhole ring sets on a concrete collar that is deep enough to reach the roof of the manhole. The manhole cover sets in the ring. the ring and cover are both isolated from the conductors below. I wonder how the dog was electrocuted? :confused:
 
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