Pole base

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GSXR600

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I am installing lighting poles on a bridge. The bridge came with 5/8" piece of steel over the edge of the bridge with a 4" radius hole cut in it to sit the pole on. I have RMC ran under the bridge then i am changing over to seal tight. The problem i am having is with the 4" radius hole in the supporing steel plate for the pole i dont have anything to keep the seal tight in the base of the pole. Anyone ever come across this. If so what did you do?
 
GSXR600 said:
I am installing lighting poles on a bridge. The bridge came with 5/8" piece of steel over the edge of the bridge with a 4" radius hole cut in it to sit the pole on. I have RMC ran under the bridge then i am changing over to seal tight. The problem i am having is with the 4" radius hole in the supporing steel plate for the pole i dont have anything to keep the seal tight in the base of the pole. Anyone ever come across this. If so what did you do?
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Let's assume you are using 1/2" flex. Weld a 1" bar accross the hole. Place a sealtite MA on 1 side of the plate and a threaded coupling on the other side with a MA in it. On that side install a piece if flex about 18" long up to that pole hand hole. (asuming there is one).

I'm guessing this is gonna ster up a fuss. Let the games begin.
 
So if i took like a 24" caddy spander bar, cut it down and layed it above the hole. Ran the seal tight up to the hand hole and just tye rap the spander bar.

This should be NEEC compliant right?
 
LawnGuyLandSparky said:
Nothing less than a solid weld will survive very long on a bridge.
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I disagree.

However, I do agree that a solid weld is the best means of fastening... but regarding conduit and such, we are still pretty much bound to mechanical means, especially concerning LFMC... and I've yet to see RMC directly welded to structural steel even in the most stringent of industrial conditions.
 
Forget changing over to LFMC and just stub the RMC up into the base of the pole through the 4" hole. Do not concern yourself with a physical connection between the pole base and the RMC - just use a brass MIGB on the RMC inside the base and install a bonding jumper. Think of it like "setting switchgear over stubups on a slab."
 
From what I understand welding is one of the very few prohibited fastening methods for conduit... You can not tell what is happening inside the conduit...

See 300.18(B)

Otherwise Lawguy's last advice is best - as they were meant to be installed like that, or use a condulet to enter the pole from the side if you can't do that. (In say maluable iron - not cast AL - which may not last long on a bridge over water.)
 
e57 said:
From what I understand welding is one of the very few prohibited fastening methods for conduit... You can not tell what is happening inside the conduit...

See 300.18(B)
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Yeh... but I do work at times in various power plants in the region, and though many times the contracts spec' work to be done to NEC, the NEC has no jurisdiction in power plants. Use to be running conduits had have steel brackets welded to the structural steel and the conduits had to be U-bolted to the brackets (not korn clamped)... but even they have gotten away from this practice since many plants stiil have lead-based paints on their structural steel.


Otherwise Lawguy's last advice is best - as they were meant to be installed like that, or use a condulet to enter the pole from the side if you can't do that. (In say maluable iron - not cast AL - which may not last long on a bridge over water.)
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I agree... running RMC all the way [up through the hole] is the best overall method.
 
Smart $ said:
Yeh... but I do work at times in various power plants in the region, and though many times the contracts spec' work to be done to NEC, the NEC has no jurisdiction in power plants. Use to be running conduits had have steel brackets welded to the structural steel and the conduits had to be U-bolted to the brackets (not korn clamped)... but even they have gotten away from this practice since many plants stiil have lead-based paints on their structural steel.
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Even then - that is not welding directly to the conduit.... I have had strut welded to steel and then attachment of conduit to that... But not a bead that could have burned through and reduced diameter of the raceway... Which is why I beleive that code exists.

FWIW - welding is not mentioned in 314 as support - nor does it exclude it either - but I dont see it as a good method of support since it can damage the box...
 
e57 said:
Even then - that is not welding directly to the conduit....
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I didn't say it was... your taking pieces of my comments and fusing them together to get one meaning... don't do that, or are you gonna make me post one sentence paragraphs ;)

I was referring to the fact if I had seen conduit welded to structural steel, it would have been in power plants where the NEC has no jurisdiction (i.e. 300.18(B) would be a moot point)... and yet I have not seen it there... and I personally know electricians (one is a good friend of mine) that could weld GRC to steel without burning through... and they are smart enough :) to know you can't do it with wire in the conduit.


FWIW - welding is not mentioned in 314 as support - nor does it exclude it either - but I dont see it as a good method of support since it can damage the box...
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Can't say I've seen enclosures or boxes welded either... but I have seen bus duct welded to structural steel.
 
LawnGuyLandSparky said:
Forget changing over to LFMC and just stub the RMC up into the base of the pole through the 4" hole. Do not concern yourself with a physical connection between the pole base and the RMC - just use a brass MIGB on the RMC inside the base and install a bonding jumper. Think of it like "setting switchgear over stubups on a slab."
Click to expand...



This idea gets my vote. It is what I would do, and sleep just fine.
 
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