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I am planning to install a Reliance Controls Manual Transfer Switch, model R510A on the side of my house next to my electrical panel. The transfer switch is 13x12x5". I am planning to install above the panel to the right of my electrical box. This panel has the cable and phone connections coming from the street. I am planning to surface mount the transfer panel and route the 6/3 inlet cord and transfer switch outlets through the back of the transfer switch and into the stud cavity.

As an aside, I am running a 6/3 romex through the attic and dropping down the exterior wall at the generator location. The inlet itself will be mounted on the surface mounted on the siding as well. I have listed 3/4" connectors for the 6/3 on both sides and will seal the boxes to the wall with duct seal and caulking around the left, right and top side.

My biggest concern is with the proximity to the phone/cable panel and height. I have not been able to find anything regarding transfer switch mounting locations or restrictions, but is there something I am missing?enter image description here

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  • Product recommendations are off topic but I would change plans and get a lock-out kit for your panel. Cheaper, only rewire is adding the generator breaker and more versatility. Yes decades back I installed those but my homes have had lock out kits, under 100$ and no rewiring as required with the R510A
    – Ed Beal
    Jun 2, 2022 at 17:40
  • Thanks @EdBeal, I did consider that, but I couldn't find an interlock kit for my panel. Aside from that, I want it to be impossible for someone to overload the generator inadvertently by forgetting to disable high amperage devices like the AC or pool. Eventually I want to upgrade the main panel (will be in a couple of years though most likely) and would probably go Interlock for that.
    – FLTCHR
    Jun 2, 2022 at 17:44
  • That's a lot of money to spend for the sake of fools. Check the aftermarket for interlocks for almost any panel. The 510 type transfer switch does not play well with GFCI or AFCI and creates hazardous conditions with MWBCs. You could also just install a subpanel and put the interlock on that; wiring is about the same as the 510 except it is safe with MWBCs and works with xFCI (because you are handling neutral correctly). Jun 2, 2022 at 19:29
  • @Harper-ReinstateUkraine, I already have the transfer switch so I think I'm going to go ahead with that. I took care to get a generator that won't have issues with GFCI/AFCI and I don't have any MWBC. This is all going to be permitted and inspected which is why I want to ensure I'm good on clearance, etc. It's also why I can't just change the panel or add a sub right now, there is no room with the current gas main situation and I don't want to do GFCI/AFCI breakers which I understand I would need to in a new panel.
    – FLTCHR
    Jun 2, 2022 at 21:34
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    Don't get trapped by "plan continuation bias". A subpanel like this does not require GFCI/AFCI to be added, the circuits are still grandfathered. If a subpanel wouldn't be legal neither would a transfer switch. I would think to put the subpanel in the same footprint as your plan for the transfer switch. It would cable up similar to the xfer switch, no need to go through the walls. Jun 2, 2022 at 21:58

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Transfer switches are very costly, dangerous because of the way they (fail to) handle neutral, and the "octopus wiring" is very complex and confusing. And they don't give you any additional breaker spaces. And the price!

I would use a regular subpanel instead

For 1/5 the price lol.

With a generator interlock in the subpanel (solves the availability issue).

Safetywise, the subpanel will handle neutral correctly. Which means it will work properly with AFCI/ GFCI (in both utility and generator mode, as Code requires!) and will not create a silent hazard with MWBCs (3-wire shared neutral circuits). You are also free to put any number of circuits in it, constrained only by the number of spaces you chose to buy when you buy the subpanel - and spaces are cheap.

How to install a subpanel off a main

Use flexible conduit to link the 2 panels - the bigger conduit the better but keep it under 2 feet.

Run your 4-wire feeder in the normal way for a subpanel, since you have conduit you can use THHN individual wires.

If easy, go ahead and move the circuit's Romex cable to the new panel. Otherwise remember that conduit?

For each circuit, you disconnect its hot and neutral wire from the breaker and neutral bar, extend with wire-nuts and THHN wire through the short conduit into the subpanel. In the subpanel, land hot and neutral normally (both wires to a xFCI breaker; otherwise neutral to the nuetral bar and hot to the breaker). This is "handling neutral correctly". Safety ground can stay in the main panel.

You end up with the same number of wires cross-connecting as the Reliance would use, except they are hot+neutral.

This means the original breaker in the old panel will be disused. Leave it there so you don't have a hole in your panel cover (a code violation). You can buy blanking plates, but they're flimsy and costly.

Those old breaker spaces can be reused, so if you had a project you couldn't do for lack of breaker spaces, now you can :)

Who knows, you might even be able to defer or cancel the panel replacement! That would be a nice savings.

If you have expectations to want a "smart panel" in the future, Eaton and Square D are positioning themselves to be major players (in their BR and HOM lines). In fact, Eaton's Remote Control breakers allow some rudimentary smart-home stuff to happen right now! So choosing one of them as the subpanel, and making it nice and large in terms of breaker spaces, might be a good hedge. Spaces are cheap, and smart breakers will not be tandems (the electronics won't fit).

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