# pole sign at gas station



## sparklito (Jan 19, 2006)

i have to bid on moving a sign at a gas station. i will need to dig a trench thru the parking lot right in the area where the tanks are buried. the sign and my trench will be at least 30 feet away from the pumps. does all of this need to be explosion proof? the panel is in a back room and i will go out the back walll 4 feet away. can i run pvc? any help would be appreciated. thank you


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## mdshunk (Mar 13, 2005)

I can see that going both ways. If this is permittable work, I'd let the exterior plans examiner make that decision. The liability involved can be great. I'll admit that the only hazardous location work I do is engineered by others, I just install it. Determining the boundaries of the classified location is always the job of the engineer, in my opinion. There are special wiring/raceway concerns within 20' of the classified location. I'd recommend that you try to wrap your head around article 514 (motor fuel dispensing stations) of the NEC as best you can. I'm concerned about the fill openings of the tanks (and associated vents someplace nearby) being within 20' of your run. I gotta tell you, if it was me, lacking engineering advice, I'd be running RMC with a sealoff at both ends; one at the sign base and another right outside the building's mechanical room. I don't know if there are any fuel codes that might also be broken by trenching over buried gasoline tanks. I wired one gasoline station in my entire career, and it was engineered from A to Z. No thought required on my part. 

_514.8 Underground Wiring. Underground wiring shall be
installed in threaded rigid metal conduit or threaded steel
intermediate metal conduit. Any portion of electrical wiring
that is below the surface of a Class I, Division 1, or a Class
I, Division 2 location [as classified in Table 514.3(B)(1)
and Table 514.3(B)(2)] shall be sealed within 3.05 m (10 ft)
of the point of emergence above grade. Except for listed
explosionproof reducers at the conduit seal, there shall be
no union, coupling, box, or fitting between the conduit seal
and the point of emergence above grade. Refer to Table
300.5._

Maybe there's some hazardous location guru lurking that will chime in here.


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## furbis (Jan 10, 2006)

MD not to step on your toes but if you read a little further 514.8 EXC NO.2 says you can run RNC if covered 2' and RMC or IMC is used for the last 2' of connection to emergence or to point of connection.


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## mdshunk (Mar 13, 2005)

furbis said:


> MD not to step on your toes but if you read a little further 514.8 EXC NO.2 says you can run RNC if covered 2' and RMC or IMC is used for the last 2' of connection to emergence or to point of connection.


Yes, it certainly does, and I appreciate that observation. Special occupancies are is far from my strong pont in the code. 

It has been further been pointed out to me by private message, _"My understanding is if you do not pass through the classified location, PVC all the way w/no sealoffs with rigid stub up is fine. Exhibit 514.5 (in the 2005 handbook) shows this pretty clearly."_

This is a fun excercise.


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## furbis (Jan 10, 2006)

I am no expert in this area either, I just took my colorado journeymans test last thursday and it was on the test.


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## mdshunk (Mar 13, 2005)

furbis said:


> I am no expert in this area either, I just took my colorado journeymans test last thursday and it was on the test.


Okay, now I don't feel so bad. The special occupancies are one thing you learn well enough to pass the test, and never study up on again until you get a job for which the 500's pertain. For instance, being how there's no marinas or boatyards within a couple of hours from me, I'd be lost if I had to wire one of them. I do a certain amount of hazardous location work each year, but I've only ever done one gas station job. I notice most of the new gas station work in my area is done by firms that I've never heard of before. They must import them from out of the area for this purpose.


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## sparklito (Jan 19, 2006)

thanx for the responses. i spoke to an inspector friend and he thought i could run pvc with rigid for the last 2 feet with the sweep up. i am concerned about the tank fill pipes being in my direct path. i am going to call the inspector near the job and try and ask his opinion. this job is 2 hours away from me so the less trips there the better. i am going to bid it for rigid the whole way and i will block off both ends for vapors


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## Teetorbilt (Feb 12, 2004)

Don't forget all of the lines to the pumps and vent lines to each tank.


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## sparklito (Jan 19, 2006)

i'm going explosion proof and rigid the whole run for the sign and the post light. the ground is red clay with lots of shale so it is one tough dig. at least if i run rigid my trench won' t need to be as deep. thanx again and wish me luck, this one should be profitable if i can get the job.:thumbup:


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## sparklito (Jan 19, 2006)

does anyone know if i can run rigid aluminum or does it have to be rigid steel? there is a big price difference between the two types of conduit.:help:


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## furbis (Jan 10, 2006)

you might check 514.8 or maybe read the whole article. your answer should be in there.


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## mdshunk (Mar 13, 2005)

The code says you can use threaded RMC or threaded ferrous IMC for that. 

So, if you're using IMC, it specifically says that it must be steel (ferrous) and threaded. That section calls out no special material type for the RMC. That being the case, you can use steel, aluminium, silicon bronze, or stainless steel RMC, since they are all listed types of RMC. One caviet though... many inspectors don't consider aluminium RMC sufficiently corrosion resistant to withstand a direct burial application (see 344.10(B)). 

I havn't personally used RMC in a very long time for anything. Mostly IMC is what we've been using, since you can use IMC just about everywhere you'd have used RMC in the past.


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