Bonding Question

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rlcemente

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I have one last question if I may;

According to UL, any metalic item (or piece of metal) that is 4 inches (or greater) in diameter must be bonded......

Where is this written in stone?

Is this something that the NEC states or???

If possible, please forward your answers for this (and my other two questions (posted to this forum earlier today) to me directly by email in addition to posting the response here.


Thank you all so much,

Roberto Clemente

(Moderator?s Note: Edited to remove email address. If you wish to send an email message to this person, then first send a Private Message via this Forum, and ask for the email address.)

[ December 08, 2005, 05:45 PM: Message edited by: charlie b ]
 
Re: Bonding Question

It might be a requirement of some UL listings, but to my knowledge it is not in general a UL requirement.

UL508a requires essentially all metallic parts of a UL listed control panel to be bonded.

14 Grounding ? General
14.1 An industrial control panel shall have provision for grounding all noncurrent carrying metal parts that are exposed or that are able to be contacted by persons during normal operation or adjustment of the equipment and that are able to become energized due to a breakdown of insulation, loose wiring connection, or electrical disturbance.
 
Re: Bonding Question

Sorry Folks... I'm aware of 250.4 (and the others)... my question is directed more with regards to UL. As I was told by a someone that any piece of metal measuring 4 inches in diameter or greater must be bonded; this being said, I was curious as to whether or not this was in fact "TRUE". And if it was, if someone knew the "entity and Code" that stated this.
 
Re: Bonding Question

Sounds made up to me, or some local inspector rule that is being taking as code.

If this dimension was accurate, sections such as 250.86 would state it. Even the exception #2 only uses the term "short" again not indicating any defined length.

[ December 12, 2005, 03:04 PM: Message edited by: bphgravity ]
 
Re: Bonding Question

The 4" rule was probably taken from 680.26(b)(3).
From the topic title I'm unsure if its applicable to this particular installation.
 
Re: Bonding Question

I am almost positive that there is no NEC rule requiring this. In fact many metal things are not required to be bonded in the NEC, such as metal siding, metal ductwork, etc. Recommended, yes; required, no.
 
Re: Bonding Question

The nec requires metal water piping systems to be bonded per 250.104 or grounded per 250.52(A)(1). Isolated metal stubs 4" or so do not comprise a metal water piping system, metal is grounded or bonded if its structural metal. A 4" lenght of metal is not structural.
 
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