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Power inlet box mounting: What is needed to go through wall?

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olytdi

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I'm installing my 30 amp power inlet box for my back up generator project. The box is a steel GE weather tight box seen here:

http://www.lowes.com/pd_206355-76863-T030N_0__?productId=4326713

The mounting holes stand out a 1/4 inch or so from the back of the box (like feet). The box will mount to the outside of the garage on T-111. What is needed to line the hole through the T-111 since the box will essentially stand a 1/4 inch out from the exterior wall?

I'm using 10/3 romex so I suspect that I need to have some sort of connecting ****** or collar that goes through the T-111 and into the box such that it is weather tight to the inside of the garage. No insulation or sheet rock -- I have access to the inside of the T-111

What's the standard for this?

Thanks!
 
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Charles (in GA)

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I'd put a PVC fitting in the box, and if needed to get to the inside of the T1-11, a short piece of conduit. Drill the hole in the T1-11 just large enough for the conduit fitting to push thru and once in place, you can figure out where your mounting holes need to be drilled in the siding.

Charles
 
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olytdi

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Thanks you guys.

I ended up putting in a plastic ****** that secured to the box on one end and on the other, is threaded inside such that I could attach a romex connector to the end that protrudes to the inside of the wall. Weather tight and has the romex secured. I just had to drill through the wall with a paddle bit and slide it in. Little bit of silicone and done.

Thanks!
 
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olytdi

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Yeah, so there are a few things that need to be accomplished with regard to getting the wiring from the power inlet box, through the back of the box and through the siding, and into the interior of the garage where it can be run to the panel.

One is that the romex needs to be secured such that if it were pulled on, you couldn't pull it off of the inlet plug inside the power inlet box -- it needs to be secure like any wire entering or exiting an electrical box.

Another is that the passage from the inside of the inlet power box to the inside of the garage needs to be weather sealed as the box stands out from the siding about 1/4 inch. So a ****** secured to the back of the power inlet box that then goes through the wall and has a romex connector attached to it's inside end addresses these requirements.

I could have probably just run a wire through a hole in the wall into the back of the box but it would have been a hack job and I wouldn't have been satisfied. This way it's safe, to code, robust, and weather tight.
 
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Speedy Petey

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Well, your latter scenario is certainly NOT a hack job and serves the exact same purpose.
I am obviously not suggesting passing the cable through the KO into the box. Of course an NM connector would need to be used.
And how is weather sealing (silicone, duct seal, etc) around the cable and different than around a conduit ******? In both cases you are sealing that 1/4" gap.

Again, how is a tiny ****** going through any different than just the cable itself?
 
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pattenp

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Speedy Petey said:
Well, your latter scenario is certainly NOT a hack job and serves the exact same purpose.
I am obviously not suggesting passing the cable through the KO into the box. Of course an NM connector would need to be used.
And how is weather sealing (silicone, duct seal, etc) around the cable and different than around a conduit ******? In both cases you are sealing that 1/4" gap.

Again, how is a tiny ****** going through any different than just the cable itself?
Click to expand...

For the purpose of meeting code, none as lone as the opening is sealed and the NM is not exposed to getting wet. I used a short ****** on my inlet box just because I like the ****** over caulking the gap.
 
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olytdi

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Well, because the power inlet box stands away from the wall to which it's mounted by about a good quarter inch, there is 1) no way to contain the romex as it passes from the box and then into the wall, and 2) no room between the box and the wall for a romex connector (without also drilling a hole large enough for the romex connector). So I hard-fixed the pipe to the box as the knockout and it will (snugly) go through the wall. All of this will be rock solid as the box is firmly mounted to the wall. On the inside where the pipe comes through, there are inside threads to which the romex connector can be attached for cable securing.
 
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Speedy Petey

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olytdi said:
1) no way to contain the romex as it passes from the box and then into the wall,
Click to expand...
There is no need to.



olytdi said:
1)2) no room between the box and the wall for a romex connector (without also drilling a hole large enough for the romex connector).
Click to expand...
Yes, that's exactly what you do. Just clearance the hole a bit to accept the NM connector (it does NOT have to pass completely through the hole). In fact, if you use a black button type there is no need at all.
 
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teamextreme

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Romex is required to be attached to the box with a connector of some kind (unless it's a single gang, plastic box, which we're not talking about). How does a ****** provide an attachment means? I understand it makes a clean install with regards to the passage through the wall and looks clean and professional and all, but I don't think it's technically legal.
 
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pattenp

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teamextreme said:
Romex is required to be attached to the box with a connector of some kind (unless it's a single gang, plastic box, which we're not talking about). How does a ****** provide an attachment means? I understand it makes a clean install with regards to the passage through the wall and looks clean and professional and all, but I don't think it's technically legal.
Click to expand...

As to securing, NM cable can be stapled within 12" of where it enters the ****** to satisfy code.
 
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olytdi

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Okay, the romex connector is connected to the ****** which is HARD connected to the box. The box to the connector is one rigid piece. Having the romex connector attached to the back of the box is a no go because the box is NOT flush to the outside wall. You'd have a romex connector and romex exposed to weather (potentially) without a pipe to transition through the wall.

I do believe you need some sort of cable anchoring associated with the box. I don't think you can simply run a wire through the pipe and have it's only attachments at the receptacle and, on the other end, at the romex staple. Anyway, maybe it's a bit overkill but that's okay.

And for those who inevitably cannot resist commenting on proper genset installs:

The power goes to the main panel with a properly installed interlock, well labeled and with full instructions mounted in the panel on how to safely lock out the main. There is no need for a transfer switch and I won't comment further on this.
 
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teamextreme

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olytdi said:
Okay, the romex connector is connected to the ****** which is HARD connected to the box. The box to the connector is one rigid piece.
Click to expand...

This makes sense and provides the romex attachment I was thinking of.

olytdi said:
I do believe you need some sort of cable anchoring associated with the box. I don't think you can simply run a wire through the pipe and have it's only attachments at the receptacle and, on the other end, at the romex staple.
Click to expand...

This is what I've always understood. I'm not sure pattenp's explanation is correct in terms of the romex entering the box. Securing with a staple is a separate requirement from the attachment to the box. I'll see if I have time to look it up tomorrow. Maybe one of the other usual suspect experts can chime in and confirm one way or the other.
 
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pattenp

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teamextreme said:
This makes sense and provides the romex attachment I was thinking of.

This is what I've always understood. I'm not sure pattenp's explanation is correct in terms of the romex entering the box. Securing with a staple is a separate requirement from the attachment to the box. I'll see if I have time to look it up tomorrow. Maybe one of the other usual suspect experts can chime in and confirm one way or the other.
Click to expand...

Once you attached the short ****** to the box the Romex's entry point is now via a raceway. Not to argue over such a minor thing, but I will say I do feel the clamp is the best way to go. I just know, at least around here, if Romex enters a sleeve that's attached to a box/panel the securing of the Romex can be done with a staple at the entry point of the sleeve. I can't find anything in the NEC that says that's not allowed.
 
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Speedy Petey

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olytdi said:
Having the romex connector attached to the back of the box is a no go because the box is NOT flush to the outside wall. You'd have a romex connector and romex exposed to weather (potentially) without a pipe to transition through the wall.
Click to expand...
Not if it's sealed properly, which is the most common way to do it. HOW could you do this and not seal around the cable??? That would not only allow the cable to get wet, but also leak into the house/wall.
The ****** way is fine and works just as good, but it is overkill.
 
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olytdi

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pattenp said:
Once you attached the short ****** to the box the Romex's entry point is now via a raceway. Not to argue over such a minor thing, but I will say I do feel the clamp is the best way to go. I just know, at least around here, if Romex enters a sleeve that's attached to a box/panel the securing of the Romex can be done with a staple at the entry point of the sleeve. I can't find anything in the NEC that says that's not allowed.
Click to expand...

Good to know. If I can remember and have my sh&t together, I'll take some pics. I'd like to post a more comprehensive post on my gen setup and why I made the decisions I did (stationary vs portable; fuel type; sizing; trans switch vs. interlock, etc.) in hopes that it helps others more clearly define their choices.

Thanks to all for feedback!
 
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