Transfer Switch FMC Connectors in Drywall

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Old 06-27-20, 02:24 PM
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Transfer Switch FMC Connectors in Drywall

I'm installing a Reliance A510C transfer switch & flush mount kit next to a flush-mounted breaker panel in a finished garage. I want to be able pass a city electrical inspection and have a couple of specific questions about whether I'll be OK code-wise.

The transfer switch and breaker panel occupy adjacent wall cavities separated by a single wooden 2x4 stud. I've already bored a hole through the stud to run the Reliance-supplied 1" FMC flex conduit through. Reliance supplied both straight and 90-degree FMC squeeze connectors, and in order to make this work at least one connector will unavoidably have to be a 90.

I want to be sure that, unlike with 90-degree conduit bodies, code allows this type of connector to be concealed in drywall -- I think it's OK, but after reading some online conversations I still haven't found a definitive answer. Can anyone confirm? Things that might be relevant are that this is a dedicated use conduit, an integral part of a UL approved appliance, and there won't ever be a need to pull any more wire through it like might be possible with a conduit body in general purpose conduit runs. Something else that I've seen mentioned that could be relevant would be that both ends are open and directly accessible from inside the two boxes.

The other question I had was regarding the normal code requirement to secure cable and flex within 12" of a box. I've seen at least one reference to hard connectors satisfying the 12" securing requirement... So would a 24" piece of flex passing through a wooden stud and attached to boxes with hard squeeze connectors on each end be OK or not?

 
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Old 06-27-20, 03:01 PM
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Since the flex is less than 6' it could be considered a whip and not be required to be secured. That said, I would just install a strap just to make it neat.

Since it came from the manufacture with the whip installed and was not field assembled I would think you would be OK installing inside a wall. However, your local inspector may disagree and they have the final say.

It seems to me that if you have the panels next to each other you would come out of the bottom of one and into the bottom of the other using two straight connectors.
 
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Old 06-27-20, 04:57 PM
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Ahh thanks, I didn't know the thing about under 6' being a whip. That certainly sounds like it ought to apply.

Just a technicality, but as far as coming already assembled, the transfer switch did come with its bundle of 4' wires already assembled into the box and threaded through an 90-degree connector on the bottom (minus the connector shell cover). All I needed to do was slide the short piece of FMC over the wires and screw down the squeeze cover, and then add the appropriate squeeze connector on the far (breaker panel) end. But an inspector certainly wouldn't need to know all that, for all intents and purposes it came assembled.

I would have liked to come out of the bottom of both boxes straight down as you suggest and then bend the flex into a U-shape, but there's an obstruction a few inches below the breaker panel that would be in the path of the flex so I need to use a 90 to route directly out of the panel and stay above the obstruction..I was planning to change the connector on the transfer switch end to a straight one, it should be easy enough.

 
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Old 06-29-20, 10:15 AM
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OK, the transfer switch has been mounted and I've pulled the circuit wires through the 1" FMC into the bottom of the breaker panel. There is a picture below of where things stand now.

Not visible behind the insulation are two romex wires coming out of the bottom left corner of the breaker panel and a receptacle box for the clothes dryer serving the laundry room on the other side of the wall. The dryer receptacle box is what necessitated the 90-degree squeeze connector and prevented simply running U-shaped FMC with two straight squeeze connectors as the FMC.would need to penetrate the stud.right where the box is.

I'd appreciate any thoughts on whether anyone sees any potential issues that could cause an inspection failure.

EDIT: Forgot to mention I will be adding a nail plate to the stud


 

Last edited by vblg01; 06-29-20 at 10:49 AM.
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Old 06-29-20, 01:19 PM
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Hi, I donít see a problem with that , I would leave it open until after the inspection.
Geo
 
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Old 06-29-20, 03:21 PM
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Right, I'll definitely wait for the inspector before covering. I guess if he has a problem with the 90-degree connector behind drywall I can always suggest one of those removable plastic access hole covers just under the breaker panel. The screws would still be pointing down instead of out, but they would certainly be accessible. Thanks very much for the input.
 
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Old 06-29-20, 03:49 PM
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If the inspector has an issue with it just tell him you will install an access panel.
 
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Old 07-09-20, 06:53 PM
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Transfer Switch Install Part II - Power Inlet Port

I've decided that I should go ahead and extend the transfer switch's power inlet port to the outside world before calling for an inspection. The majority of the run would be in approximately 20 feet of surface-mounted conduit that would run along top of one wall the length of the finished garage just below the ceiling.

The power port is 50A, so I would plan to use #8 individual THHN conductors in 3/4" conduit. To get up to the ceiling from the flush-mounted transfer switch I was thinking I would use 6/3 W/G NM-B romex from the knockout on the bottom left of the switch and loop it up around the right side of the switch (see picture above) and up to just behind the drywall where the surface mounted conduit begins.

I've been dithering about how to do this in the most code and inspector friendly way. I was afraid that trying to penetrate the drywall into a surface-mounted box might raise bend radius red flags, so I've been thinking I would mount a square box inside the stud cavity at the top just behind the drywall so that the romex could enter straight in from the bottom. Then I would add an extension ring and blank plate to the box that would stick out of the drywall enough to allow me to connect the surface-mounted conduit to a side knockout on the ring. I sure hope the knockouts on the box and ring are far enough apart to accommodate the 5/8" sheetrock. Has anyone ever done this?

Besides the sheetrock clearance issue, my main worries are whether there are any code issues doing it this way I'm assuming there's no code issues splicing 6 gauge romex to 8 gauge THHN and they don't all have to be the same gauge.
 
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Old 07-09-20, 07:30 PM
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Using a box in the wall and extension ring is for sure an option. You will have to make sure that the box has enough space for 3 #6 wires, 3 #8 wires, and 1 #10 wires (The grounds only count once).
 
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Old 07-09-20, 08:04 PM
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Since the 6/3 romex requires a knockout for a 1" clamp the square box and ring would need to be the larger 4-11/16" size. I think the box by itself would meet the fill volume requirement and the additional volume from the ring would be gravy. I don't know how accurate it is but the online calculator I used for three #6, three #8, and one #10 came out to 24in^3. The box should be ~42in^3.
 
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Old 07-10-20, 05:08 AM
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Hi, what is above the ceiling, any chance of drill through the top plate and fishing the cable down the wall?
Geo
 
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Old 07-10-20, 05:51 AM
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I did look at going up and out of the top plate, but once I get beyond that area it becomes too impractical with various other obstacles. I would have loved to keep this all romex in the ceiling or behind drywall, but the effort would totally exceed my threshold of pain.
 
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Old 07-10-20, 10:43 AM
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I would use 2 offset conduit bends to come out of the transfer switch and through the drywall. No extra connections or junctions, you'll just have to spackle or caulk around the conduit penetration.
 
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Old 07-10-20, 03:16 PM
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Since the 6/3 romex requires a knockout for a 1" clamp the square box
6/3 Romex will easily fit in a 3/4" twin-screw connector.
 
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Old 07-10-20, 03:31 PM
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I would use 2 offset conduit bends to come out of the transfer switch and through the drywall. No extra connections or junctions, you'll just have to spackle or caulk around the conduit penetration.
I assume you're suggesting something like a couple of opposing 45-degree EMT elbows that would zig-zag out of the drywall. Thanks, that's an interesting thought and I'd be totally fine with the look. But I still can't envision a way to deal with the knockout being on the bottom of the transfer switch and how to turn the conduit up within the roughly 12" distance between the knockout and the farthest away stud in that cavity.

I was really hoping for a path along the top of a particular wall, but I suppose I'll have to consider wheter I could go down the opposite wall down low which would allow for the idea you suggested.
 
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Old 07-10-20, 03:35 PM
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6/3 Romex will easily fit in a 3/4" twin-screw connector.


Ahh, I wasn't really sure about that so I was playing it safe with the 1" clamp.

 
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Old 07-11-20, 06:30 PM
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But I still can't envision a way to deal with the knockout being on the bottom of the transfer switch and how to turn the conduit up within the roughly 12" distance between the knockout and the farthest away stud in that cavity.
I should have realized the knockouts were on the bottom of the transfer switch. In that case, I'd do something similar, use 16" of FMC and do a U-turn, out the bottom of the switch, out the drywall, and u-turn vertically towards the ceiling. Then convert to EMT to get to the ceiling.
 
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Old 07-12-20, 10:09 AM
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I'd do something similar, use 16" of FMC and do a U-turn, out the bottom of the switch, out the drywall, and u-turn vertically towards the ceiling. Then convert to EMT to get to the ceiling.

Early on I had briefly considered coming out of the bottom of the switch with FMC before leaving that idea and going off in other directions. Thanks for snapping me back.

A minor caveat in my case is there will only be an inch or less gap between the breaker panel cover and the edge of the bezel of the transfer switch's flush mount kit, so rather than coming out of the wall and running EMT up between them I would just stay inside the wall with FMC up to the surface mount 4" box up at the ceiling. I could then bring the FMC out of the wall just below the box, but for that matter with 3/4" FMC having a 4" minimum bend radius I might have just enough room to make the bend out of the 2x4 stud bay, through the 5/8" sheetrock, and then directly into the back of the surface box. That would be an even cleaner look. Depending on which way I did it I'd have about 4-5 ft of FMC with a total of either 180 or 270 degrees of bends.

Another benefit would be that I could stay with individual #8 THHN wires from start to finish and not have to splice in a short piece of 6/3 NM-B.
 
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Old 07-17-20, 12:56 PM
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Transfer Switch Remote Power Inlet Box Mounting

So now I'm trying to figure out how best to mount a remote power inlet box and if it's even possible to do in my situation in a code/inspection friendly way.

I've seen that remote power inlet boxes should be mounted at least 5-ft. away from doors, windows, etc., but my garage is pretty much landlocked with the only accessible outside wall being a narrow column next to the big garage door. The only place for mounting a box would be less than two feet from the garage door. So is this 5-ft requirement in the code somewhere, and if so would it also apply to garage doors? I'm not sure what the point would be since I would think they're already expecting car exhaust fumes in a garage.

The only other possibility I've considered is stopping short of penetrating the outside wall and mounting the inlet box just inside the garage door. I know a lot of people mount their car charging ports just inside the garage door like this, but I seem to remember seeing somebody question whether this violates code. The UL-approved transfer switch already has an integral power input port built-in on the front panel, so again I don't know what the point would be of a rule that said you can't extend it further inside a garage.

Anybody have thoughts on either of these two code/inspection issues?
 
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Old 07-17-20, 01:19 PM
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I haven't had or seen any inspection issues with the location of a generator receptacle.
Most of the location requirements are referring to a generator install...... not the receptacle.

You can use a longer interconnect cord to keep the generator away from the house.
 
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Old 07-17-20, 03:51 PM
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Great, thanks, that's what I was hoping to hear. I'll have a power cord long enough to allow enough distance between the portable generator and the house.

Now I'm pretty much down to deciding whether I want to drill a hole through my fairly new insulated vinyl siding large enough to pass thru a 3/4" liquid tight connector or just keep the inlet box just inside the garage door. That'll give me something to contemplate until I run the EMT over to that corner..

 
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Old 07-17-20, 04:51 PM
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That's what I do..... drill a hole in the back.

I hold the box up on the siding with the top of the box just under the lip of the siding. I mark and drill the hole. I put a bead of silicone along the top of the box (under the siding lip) and around the hole. I've never had one leak.
 
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Old 07-17-20, 06:08 PM
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Thanks very much for the tip! I've been thinking about exactly how I'd mount a box against the plank-style surface of the siding without having water problems, so your advice is appreciated. The Reliance PBN50 plastic enclosure I'm planning on using only has rear and side ko's, and since there isn't much real estate on either side I was already knew I would need to come into the rear ko. Since there will be at least one gap between the box and the siding I figure I would use a short stub of liquid tight and waterproof connector to feed from the box through the wall and into a 4x4 pull box inside.
 
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Old 08-06-20, 01:07 PM
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New Path For Power Inlet Feed

Despite my usual bad timing, I managed to get the Reliance manual transfer switch connected to my breaker panel a couple of weeks ago, just before Tropical Storm Isaias plowed past here and knocked out power for a day and a half. Hoo-ray! So nice, I would have really been fried if I hadn't gotten that done before losing power.

But enough gloating, I still need to move the 50A power inlet port to an exterior wall. I was all set to run EMT & THHN/THWN across the garage ceiling and mount a power inlet box out front next to the garage door, but for a couple of reasons I've re-thought that and am now investigating a path from the transfer switch in the attached garage at the front of the house to a rear exterior wall. This had originally been my first choice before giving up way too easily. After re-examing it I've decided it's feasible.

So, the path would be through a chamber built around some HVAC ductwork. The duct chamber is a 2"x2" wood frame covered with sheetrock running continuously through the garage, utility room, and rear bedroom along the top of a wall. Today I managed to get an inspection camera in there and see that running parallel to the insulated sheet metal duct are a natural gas pipe and a couple of wires. One of the wires looks likely to be 12/2 romex and the other is probably phone or coax communication wire.

Is there any code reason I can't just fish some 6/3 w/g NM-B wire in there and lay it right beside those other things along that same path?






 
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