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#92072 - 02/25/05 06:07 AM Physical Protection  
shortcircuit  Offline
Member
Joined: Jun 2004
Posts: 608
massachusetts
When isolated (not continuous between enclosures) sections of metal conduit are used for physical protection of nonmetalic cable,like for a floor penetration for exsample, is it required to be grounded?

Code refrences please.

shortcircuit


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#92073 - 02/25/05 09:52 AM Re: Physical Protection  
George Little  Offline
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Joined: Jan 2004
Posts: 1,489
Michigan USA
Maybe 250.86 Exception No 2 covers the question.


George Little

#92074 - 02/25/05 10:38 AM Re: Physical Protection  
shortcircuit  Offline
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Joined: Jun 2004
Posts: 608
massachusetts
Thanx George Little...and what determines the distance of "short sections"...

For example could I penetrate a plastered wall with romex, enter 30 feet of EMT with bushings on each end and exit the other end and go back into a wall on the other side of the garage without grounding the EMT at all? The EMT would be provideing physical protection of the romex.

shortcircuit


#92075 - 02/25/05 03:02 PM Re: Physical Protection  
gfretwell  Offline


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Joined: Jul 2004
Posts: 9,099
Estero,Fl,usa
From a practical sense, the most likely places where a cable could energize the sleeve are the ends, so the length won't change that risk much. If you are talking about the raceway being energized by an unrelated circuit we fall back to the arguments about bonding that steel beam.
(and we don't want to kick that tar baby again)


Greg Fretwell

#92076 - 02/25/05 05:21 PM Re: Physical Protection  
shortcircuit  Offline
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Joined: Jun 2004
Posts: 608
massachusetts
gfretwell...I was not thinking so much about the may become energized from the outside, but was thinking what would happen if this EMT providing physical protection were to become damaged itself from a inadvertent impact of some sort and then becoming energized by the circuit it protects.
Guess that I'm reaching again [Linked Image]

shortcircuit


#92077 - 02/25/05 05:47 PM Re: Physical Protection  
gfretwell  Offline


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Joined: Jul 2004
Posts: 9,099
Estero,Fl,usa
I guess the real question is how you would bond the raceway to the RX without a box to open up the jacket in.


Greg Fretwell

#92078 - 02/25/05 08:51 PM Re: Physical Protection  
earlydean  Offline
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Joined: Dec 2003
Posts: 751
Griswold, CT, USA
The same way we have to bond that steel 90 in the UG service PVC run that isn't 18 inches below grade. With a ground clamp or bushing and a wire to the ground bus in the panel.


Earl


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