[RE-wrenches] Grounding - Exposed Metal Part

[markf at berkeleysolar.com]

Thanks Drake,

My question goes to the situation where the two plates are in physical
contact, but without any other provision to mechanically connect or
electrically bond them.

Mark


> If the plates are bolted together,  then they are bonded to each other.
>
> At 01:33 AM 7/27/2012, you wrote:
>
>>Mark,
>>If you look at NEC 250.104(C), you'll find that you have to bond
>> structural
>>metal that is "likely to become energized". The phrase "likely to become
>>energized" is not defined, and is up to the AHJ. I would guess most AHJ's
>>would consider the second metal plate to already be bonded since it is
>>electrically continuous with the first metal plate, because they're
>>touching. I also doubt they would consider it "likely to become
>> energized"
>>because you bonded the first metal plate. Just my opinion.
>>
>>-Hans
>>
>>-----Original Message-----
>>From: re-wrenches-bounces at lists.re-wrenches.org
>>[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Mark Frye
>>Sent: Wednesday, July 25, 2012 7:29 PM
>>To: RE-wrenches
>>Subject: [RE-wrenches] Grounding - Exposed Metal Part
>>
>>A bare metal plate is connected to a conduit which serves as an equipment
>>ground. The plate is grounded and needs to be grounded because it could
>>become energized both by being contact with the conduit which could
>> become
>>energized and also by coming into contact with the current carrying
>>conductors themselves.
>>
>>A second bare metal plate touches the first plate but could not come into
>>contact with the current carrying conductors.
>>
>>True or false, the second plate does not have to be grounded (bonded to
>> the
>>first plate) because the first plate is already grounded and therefore
>> could
>>not cause the second plate to become energized?
>>
>>Any Code references to support your opinion?
>>
>>P.S. I believe: "false", the second plate must be bonded to the first
>> plate
>>because it may become energized by the first plate regardless of whether
>> or
>>not the first plate is actually grounded, but I can't find references in
>> the
>>Code to support this.
>>
>>Mark Frye
>>Berkeley Solar Electric Systems
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