Rooftop GFCI

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wireday

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Is it ok to come off the bottom of disconnect with an 1/2 inch offset nipple to a bell box for the service GFCI ?
 
wireday said:
Is it ok to come off the bottom of disconnect with an 1/2 inch offset nipple to a bell box for the service GFCI ?
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Yes. Presuming this is for AC unit - you can not connect the receptacle to the load side of the disconnect. Also can not tie a 15/20 amp receptacle directly to other than 15 and 20 amp branch circuits and would need a neutral conductor as part of those circuits if that is what you are tying into - so often you will be running a separate circuit to the roof for the receptacle - nothing prohibits it from being run in the same raceway that supplies the AC unit though.
 
Thanks Kwired, Yes I have a separate 120 volt circuit, what I was wondering is coming off the bottom of disconnect with offset nipple OK, If water would be an issue or not.
 
wireday said:
Thanks Kwired, Yes I have a separate 120 volt circuit, what I was wondering is coming off the bottom of disconnect with offset nipple OK, If water would be an issue or not.
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The issue here could be in details of listing. Many inspectors will let you do this, but if you look into listing details, chances are your offset has non tapered threads and your outlet box hub is likely listed for tapered thread meaning it must have threaded RMC/IMC inserted into it to completely comply with listing. EMT fittings also have straight threads - and there are millions of them installed in such boxes anyway.

I would drill a weep hole in the outlet box regardless, even if your threads don't leak, you likely still get some condensation in the box and need to drain it.
 
I wonder if they make RMC threaded offset nipples, looks like Crouse Hinds mentions one, not a lot of info on the threads.
 
You also need to watch for this.

210.23(A)(2) Utilization Equipment Fastened in Place. The total rating
of utilization equipment fastened in place, other than luminaires,
shall not exceed 50 percent of the branch-circuit ampere
rating where lighting units, cord-and-plug-connected utilization
equipment not fastened in place, or both, are also supplied.
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Also you need a neutral in the box also
 
Dennis, I do have a 120V circuit with a neutral, Are you thinking someone might get a hot from the disconnect and use the egc for a neutral.
 
wireday said:
Dennis, I do have a 120V circuit with a neutral, Are you thinking someone might get a hot from the disconnect and use the egc for a neutral.
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I have seen that done :).... I didn't really make that comment for you as I was pretty sure you knew but it was meant for others that may be viewing that don't know.
 
If there are, it would defeat the purpose.
Tapered threads tighten up and seal when the gap between the two tapers closes up, regardless of orientation.
The purpose of an offset nipple is to provide an arbitrary orientation. To use it for that, you would need to leave the tapered threads incompletely tightened -- and incompletely sealed.

A large o-ring -- 2 or 3 mm cross-section or so -- would probably seal adequately for a rain-tight installation. (but wouldn't be listed)
 
If using a bell box, drill a small hole in the bottom to let the water out. I would always use SS screws on recpt and cover but the WR recpts have SS screws.
duct seal on the inside over any threaded KO plugs, think the instructions mention this. I would silicone between the inuse cover and box
 
wireday said:
Dennis, I do have a 120V circuit with a neutral, Are you thinking someone might get a hot from the disconnect and use the egc for a neutral.
Click to expand...

tom baker said:
If using a bell box, drill a small hole in the bottom to let the water out. I would always use SS screws on recpt and cover but the WR recpts have SS screws.
duct seal on the inside over any threaded KO plugs, think the instructions mention this. I would silicone between the inuse cover and box
Click to expand...
Drill the weep hole and move on. Any thing else you do is a waste of time. Bottom line is if any sealing effort fails you still potentially fill/partially fill the box with water. Even well sealed box can still fill with condensation.
 
same circuit for GFCI

same circuit for GFCI

Dennis Alwon said:
You also need to watch for this.




Also you need a neutral in the box also
Click to expand...

Let us say the AC unit needs 20 amps 240 volts. Would it be permissible to simply run a neutral with the two hot conductors to supply the GFCI with 120 volts?
 
Greg1707 said:
Let us say the AC unit needs 20 amps 240 volts. Would it be permissible to simply run a neutral with the two hot conductors to supply the GFCI with 120 volts?
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Yes, but the fixed load (the AC) must be 10 amps or less to be able to place the receptacle on the same circuit.

Seen this rule cheated a few times - reality is that receptacle is mostly only used when the AC unit is not in service
 
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