wiring questions for inlet box to transfer switch

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  #1  
Old 11-27-12, 05:20 PM
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wiring questions for inlet box to transfer switch

Hi - I'm looking for some advice on inside wiring between an outdoor inlet box and an inside transfer switch, for generator use. I'm located in Mercer County, NJ. I realize that everything is subject to local codes and inspections. I am simply looking for general guidance on what would be a reasonable starting point to propose to my inspector.

- I have a transfer switch wired into my panel already (Reliance 30216A, the direct connect model, not the plug-type)
- I am looking to install an outdoor-rated L14-30 inlet box, attaching it to the outdoor wall (vinyl siding over plywood)
- my generator is 120V 30 A max
- unfinished basement, cinder block walls. Estimated 30 ft linear cable distance from inlet box entry location to transfer switch.
- cable would presumably run down about 3-4 feet from hole drilled through wall above cinderblocks, horizontally along one wall about 12 feet, make a 90deg bend, run another 10 ft to the transfer switch

My primary questions are on the recommended type of cabling, how I handle turns, and how I attach the cabling to the cinder block walls. I am looking for ease of installation primarily, and am willing to spend some more $$$ if needed to minimize the amount of work I need to do. I am also looking for guidance on how to run the cable through the wall out to the inlet box.

Would 10/3 armored cable, attached to the cinderblock walls with metal clamps be the easiest option?

What's general best practice for passing this type of cable through the wall to the inlet box?

Thanks
 
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  #2  
Old 11-27-12, 05:39 PM
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Would 10/3 armored cable, attached to the cinderblock walls with metal clamps be the easiest option?

What's general best practice for passing this type of cable through the wall to the inlet box?
That would be a reasonable option IF you use steel armored cable. I would suggest using steel MC cable such as MC Tuff. PVC jacketed cable would also be acceptable, but the cost would probably be prohibitive as it would probably be a special order. I'd stick to the steel cable.

http://www.afcweb.com/pdf_/afc_1001_mctuff_120.pdf

You cannot directly attach aluminum clad cables or aluminum conduit to a masonry or concrete wall nor can you penetrate a wall of this construction with any type of aluminum cable or conduit.
 
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Old 11-27-12, 05:56 PM
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Thanks CasualJoe and congrats on your 3Kth post.

Would this be a suitable type of cable also? Available at HD in a 50' length.


(steel, 10/3, copper solid)

50 ft. 10/3 Gauge BX/AC-90 Cable-1408N24-00 at The Home Depot
 
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Old 11-27-12, 06:14 PM
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I couldn't quite figure out if the wire is going to be run outside at all, or if the wire will just penetrate through the wall and enter the back of the inlet box.

If the wire is run outside, it needs to be UF in protection (I don't believe AC is outdoor rated, though I may be wrong). If you're just penetrating the wall into the inlet box, you can use NM-B or AC without an issue.

On the interior, if you can run the wire along the joists or rim joist, where it's not subject to damage, you can use NM-B (Romex), which will be cheaper and easier to work with. Otherwise, you'll have to either sleeve it in conduit or as stated use AC or MC.

You actually may be better off just using PVC conduit and running 10ga THWN wire in it. With only two bends, it'll be an easy install and easy pull.

Just some options to consider...

-Mike
 
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Old 11-27-12, 06:28 PM
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Thanks Zorfdt. The cable will have no outside runs - it will simply penetrate the wall to the outside and enter the inlet box, as you stated.

I could run the cable along the basement ceiling joists but there's a lot of other stuff up there already to snake around and I prefer to work at eye level or slightly above/below. As for the rim joists there are 2 windows in the foundation that I would have to go either above or below.

Manually pulling wire through conduit is something I would like to avoid. I am willing to pay extra for this convenience. I think it will be 3 bends actually, one pointing down from the wall point of entry, another turning to the right to start going horizontal along the wall, and then one around the room corner. Are there any limitations on number of 90deg bends for AC within a given run length?

What clamps would I use to secure the AC, either for the cinderblock path or the joist path, something like this:

1 in. 1-Hole Strap, Electrical Metalic Tube (EMT) (50-Pack)-61510B at The Home Depot


Thanks
 
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Old 11-28-12, 05:45 PM
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Would this be a suitable type of cable also? Available at HD in a 50' length.


(steel, 10/3, copper solid)
I prefer stranded conductors to solid, #10 solid conductors are not easy to work with. The specs say this cable has a 16 awg ground, I prefer and would suggest a full sized green ground conductor. I assume the ground is in the metal sheathing.

What clamps would I use to secure the AC, either for the cinderblock path or the joist path, something like this:

1 in. 1-Hole Strap, Electrical Metalic Tube (EMT) (50-Pack)-61510B at The Home Depot
That strap is a little big. I prefer Jiffy 125 one hole straps, but you may find an equivalent in another brand.

Minerallac 125 - 1/2" Standard Jiffy Clip :: Rigid One & Two Hole Straps :: Conduit & Fittings :: Electrical Supplies | Lighting | Motors | - Galesburg Electric Inc
 
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Old 11-28-12, 06:30 PM
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Thanks again CasualJoe. Ideally I would like to try to limit this project's supply to things I can pick up at HD. However where would I get the MCTuff in a 50' length. I understand your point about stranded vs. solid. However would the solid cable and clamps I linked to be generally acceptable code-wise?

Also are there any guidelines on number of clamps/straps per unit length, or near bends?
 
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Old 11-28-12, 06:51 PM
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would the solid cable and clamps I linked to be generally acceptable code-wise?
I think that would be acceptable, just not my choice. Sometimes your choices are limited at the box stores, but they do offer the advantage of the short 50 foot roll. I believe I would suggest a strap at about 3 foot intervals and about 8" from the ends. The straps in your link were 1" conduit straps and those are just too big. If you must use a regular conduit strap, look at the 1/2" EMT straps, but I think those would still fit loosely. See if they have any straps smaller than 1/2".
 
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Old 11-28-12, 06:56 PM
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Thanks again. I understand and agree with your point about the clamp size, I did not look at the size when I posted the link.

I think this will be my last question for now - for 10/3 solid, does it come in other armor outside diameters other than 1/2"? If it comes in 3/4" diameter also, should I be using 3/4" diameter 10/3 instead - question being are there rules around what max % of the conduit x-section can be filled by wire, for residential applications?
 
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Old 11-28-12, 07:07 PM
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I don't believe you'll find 10-3 in a diameter anywhere near 3/4" and they typically don't come in various diameters. 8-3 MC cable is probably about 3/4". Actually, I believe you can make the 1/2" straps work, but they won't be a perfect fit.

question being are there rules around what max % of the conduit x-section can be filled by wire, for residential applications?
Those rules don't apply when using armored cables.
 
  #11  
Old 11-29-12, 06:42 AM
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Thanks again for all your help.
 
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Old 11-29-12, 10:54 PM
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Are there any limitations on number of 90deg bends for AC within a given run length?
No, and you don't actually bend it to 90[SUP]o[/SUP] anyway, at least not in the sense that you bend pipe. The limitation on degrees of bend applies to bends in conduit through which individual conductors or datacom cables will be pulled.
 
  #13  
Old 12-01-12, 05:46 PM
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Understood - the conduit makes a 90deg turn, but not a 90deg angle. What would be the typical smallest allowed radius fo ra turn around a wall corner?
 
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Old 12-01-12, 06:14 PM
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What would be the typical smallest allowed radius fo ra turn around a wall corner?
Maybe 4 or 5 inches? Every batch of cable is different. You just have to stop before it starts to oprn up and then relax it a bit.
 
  #15  
Old 12-03-12, 03:37 PM
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Thanks, will do.

Any advice on best practices for passing the conduit through to the outside?

I plan to drill the smallest possible hole through the rim joist and vinyl siding, pass the conduit through, mount the inlet box around the hole, wire the connectors, then caulk as needed. The inlet box has a receptacle cover and has the receptacle downward-facing.

What size hole would I drill for 1/2" conduit?

Does the conduit then need to be encased in anything else as it passes through the joist?, or is there any sort of fitting or clamp needed when passing through?

Thanks
 
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Old 12-03-12, 04:18 PM
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Any advice on best practices for passing the conduit through to the outside? I plan to drill the smallest possible hole through the rim joist and vinyl siding, pass the conduit through... What size hole would I drill for 1/2" conduit?
7/8" for 1/2" EMT, IIRC, without getting my hole saw set out to check. Why are you using conduit? what will be in it?

mount the inlet box around the hole, wire the connectors, then caulk as needed.
Don't caulk under the inlet box.

The inlet box has a receptacle cover and has the receptacle downward-facing.
The receptacle (female) or the inlet (male)? And that's an in-use cover, right?
 
  #17  
Old 12-04-12, 05:13 PM
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Sorry - I was using the word conduit to refer to the 10/3 armored cable itself. I take it from your answer that I will just pass it as-is through the cut opening and not encase it in anything else. If that's the case, how do I "secure" it to avoid cable strain on the connections that I will make in the inlet box.

Yes understood on the caulking.

I plan to use this cover:

30A L14-30 Power Inlet Box w/ lid WiseSales.com

Yes, getting the terminology - yes, the female receptable on the cable is plugged into by the male prongs in the inlet.

"retains raintight rating while in use" = "in-use cover" correct?
 
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Old 12-04-12, 07:19 PM
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how do I "secure" it to avoid cable strain on the connections that I will make in the inlet box.
With a cable connector.

yes, the female receptable on the cable is plugged into by the male prongs in the inlet.
OK, got that.

I plan to use this cover:

30A L14-30 Power Inlet Box w/ lid WiseSales.com

"retains raintight rating while in use" = "in-use cover" correct?
Kinda pricey but yes that'll work and yes, that means pretty much the same thing. This is actually what I had in mind: In-Use Covers.
 
  #19  
Old 12-05-12, 08:09 AM
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For the cable connector, it looks like even if I drill a 7/8" hole through the rim joist and vinyl siding (for the 10/3 armored cable pass-through), I will still need to use a 1-1/2" spade bit or similar from the outside to carve out a wider place, say 3/4" deep, for the screw-and-clamp side of the cable connector to live in, since the inlet box would need to be flush against the siding (or close to flush).

I looked through all the in-use covers on the Intermatic site you sent, and I know that is just an example of one manufacturer, but I didn't see any that also included the actual inlet. So it seems like I would have to get my own round inlet and mount it in the in-use cover correct? If that's the case then, for me, I think the easiest solution would be the ready-to-go inlet box, even though it appears to be a few bucks more than then the total cost of the in-use cover and inlet - please tell me what I misunderstood here.

Thanks
 
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Old 12-05-12, 01:18 PM
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I think the easiest solution would be the ready-to-go inlet box, even though it appears to be a few bucks more than then the total cost of the in-use cover and inlet - please tell me what I misunderstood here.
You're fine. When you referred to that as an inlet box, I just glanced at it and didn't notice that it included the inlet. That's why I said it seemed a bit pricey.

For the cable connector, it looks like even if I drill a 7/8" hole through the rim joist and vinyl siding (for the 10/3 armored cable pass-through), I will still need to use a 1-1/2" spade bit or similar from the outside to carve out a wider place, say 3/4" deep, for the screw-and-clamp side of the cable connector to live in, since the inlet box would need to be flush against the siding (or close to flush).
Yes, that's right. FWIW, I wouldn't drill anything until I had the cable and clamp in hand and could measure them. Also FWIW, I start drilling for step-down bores on the outside, and use a hole saw for the first cut. That gives me a 1/4" pilot bore to follow as I cut the second bore. Sometimes I mount the hole saw on my 12" x 1/4" bit and run the pilot hole all the way through. Other times, I drill the wider, shallower first hole with a nail-eater bit and just use the hole that the tip of that leaved to center the bit for the narrower hole. A good spade bit will leave you that same centering point. Lots of ways to skin that cat.

Here's a question: To mount that flat-backed box, won't you need to mount an escutcheon, or mounting block, first? Even if you have to make one out of PT wood? If so, then your hole would be bored through that unless it came as a ring, wouldn't it?
 
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Old 12-05-12, 05:41 PM
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Got all the above.

For mounting what about something like this:

Dutch Lap Surface Block #117-Bright White-130110008117 at The Home Depot
 
  #22  
Old 12-05-12, 06:07 PM
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That looks like it would work fine as long as you have something to solidly attach the inlet to.
 
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Old 12-05-12, 09:41 PM
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At 6-5/8" square, outside dimensions, that particular block doesn't look big enough to be a good fit for a box that's 6" wide. But yes, something like that.
 
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Old 12-16-12, 01:47 PM
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Thanks again all for your time.
 
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