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#71853 - 11/07/06 09:06 PM Supporting of raceways
Luketrician Offline
Member

Registered: 07/08/06
Posts: 273
Loc: Sale Creek, TN USA
Hello to all,

Noticed something today here at the plant. A run of 3" ridgid coming from a mcc to a 130hp motor goes through a hole in an I beam then ninetys up to the motor itself. There is a nice weld bead that circumfrences the conduit. Looks like a violation of 300.18 (B). In this paragraph though, it goes on to state the following:

"unless otherwise specifically designed to be or otherwise specifically permitted to be in this code"

Would the "specifically designed" statement be refering to an engineering design call that might have been made to allow this type of install to happen?

Luke

[This message has been edited by Luketrician (edited 11-08-2006).]
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Luke Clarke
Electrical Planner for TVA.


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#71854 - 11/08/06 03:56 AM Re: Supporting of raceways
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
In my opinion that section requires that the section of raceway be specifically designed by it's manufacturer for weld mounting.

A bulkhead fitting would be an example of a raceway section that might be specifically designed for welding.
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts

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#71855 - 11/08/06 04:03 AM Re: Supporting of raceways
LarryC Offline
Member

Registered: 07/05/04
Posts: 782
Loc: Winchester, NH, US
I thought the NEC doesn't apply to power generation facilities. Plus, I bet the local electrical inspector hasn't been allowed in.

Larry C

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#71856 - 11/08/06 08:45 AM Re: Supporting of raceways
SteveFehr Offline
Member

Registered: 03/19/05
Posts: 1192
Loc: Chesapeake, VA
RC is a steel pipe, it's inherently weldable. Why would there be any problems welding it to structure?

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#71857 - 11/08/06 09:05 AM Re: Supporting of raceways
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
Because the code says so?

Perhaps it's the fact welding tends to remove the required corrosion protection?

Or that improper welding techniques could lead to slag / sharp edges inside the raceway?

I don't have a real answer Steve but to look at another way is why should I weld it when there are so many products designed to support ridge pipe?

Bob
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Bob Badger
Construction & Maintenance Electrician
Massachusetts

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#71858 - 11/08/06 11:00 AM Re: Supporting of raceways
wa2ise Offline
Member

Registered: 11/29/02
Posts: 773
Loc: Oradell NJ USA
 Quote:
Why would there be any problems welding it to structure?


I would hope the welding work was done before the wires were put in it... Can you say "melted insulation"?

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#71859 - 11/08/06 04:13 PM Re: Supporting of raceways
Luketrician Offline
Member

Registered: 07/08/06
Posts: 273
Loc: Sale Creek, TN USA
I think you're right LarryC, It seems to me that the NEC is 'trumped' by the design engineers here at the plant. Is this a good thing?? That question is debateable...

The conduit does have plenty of enamel covering the weld joint though. No rust is visible. I would snap a few pictures for the forum, BUT..I might get into some trouble if I start taking pictures of 'vital' plant equipment.

Wondering about the statement "specificaly designed by it's manufacturer for weld mounting", the hole looks to have been made with a cutting torch, not to pretty. I'll be looking into this further, any more comments would be appreciated, thanks guys & gals.

Luke
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Luke Clarke
Electrical Planner for TVA.


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