AFCI and GFCI with a Manual Transfer Switch

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  #1  
Old 04-08-16, 09:34 AM
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AFCI and GFCI with a Manual Transfer Switch

After a 10-hour power outage this past weekend, I decided to bite the bullet and buy a transfer switch for my generator. The rats nest of extension cords all over the house was effective, but did not allow me to run my furnace. Thankfully the fireplace kept temps in the mid-60s downstairs.

I purchased a Reliance Controls Pro/Tran manual transfer switch, model A510A. It's a 10-circuit switch with standard breakers installed. They are swappable. It comes with 20-amp breakers standard.

It installs by looping the circuit through the transfer switch and back to the service panel. So when running off the generator power is going through the MTS breakers rather than the breakers in the panel. Therein lies the rub.

I have a portable, floating-ground generator.

I've done a ton of Googling on the subject and have not found definitive answers to 2 questions:

1) Will AFCI breakers function in the MTS? Both ground and neutral from the MTS go to the respective bars in the service panel. There is no switched neutral. My understanding is that powering the AFCI circuits through non-AFCI breakers from the generator is a code violation. I understand the (infinitely small) risk and I'm willing to live with that but would obviously like to install AFCI breakers if they will work.

2) Will the GFCI circuits work or will the GFCI trip immediately (I'm thinking no but I have to ask)? I do not have any GFCI breakers - just GFCI receptacles. With only 10 spots on the transfer switch, I don't want to power the GFCI circuits if they're just going to trip anyway.
 
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Old 04-08-16, 09:51 AM
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AFCI and GFCI devices will not work when there is a shared neutral AFTER the protective device. If the neutral is combined prior to the *FCI, the device is blind to that fact. GFCI receptacles will behave the same when powered from mains or a generator.

AFCI and GFCI breakers will not work in a transfer panel unless you are also able to switch the neutrals between the panels. This however in itself would be a code violation as switching a neutral is a safety hazard.

This is perhaps a good argument for using an interlock kit on your main panel instead of a separate transfer panel. With an interlock, the *FCI devices will work the same when you are on generator power as when you are on mains power. There are some other variations on this theme in which you could put all of the AFCI and GFCI devices in a separate panel, and then provide a 60A or 100A LINE-OFF-GEN switch between that panel and the main panel. Likewise a full size manual transfer switch could be installed on your service entrance to transfer the entire main panel to the generator, but these options are of course more involved and expensive.
 
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Old 04-08-16, 10:37 AM
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Thanks! You just saved me a few hundred bucks. I hadn't considered a lockout. It's simple and code compliant. Back feeding the panel is far less complicated too!
 
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Old 04-08-16, 03:21 PM
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So I was able to catch the vendor of the transfer switch before he shipped. Got my $365 back. Have been looking at lockouts. I have a GE load center. Home Depot sells a GE-manufactured lockout for the panel. The genny breakers need to be in the top right position. I'd need to move 10 breakers down 2 positions, which shouldn't be an issue assuming there's enough slack in the wiring.

My current gasoline-powered generator is only 3500 running watts. I aspire to acquire a 7,500 watt or better propane/NG generator in the near future. Long story but I'm converting my home to natural gas. Construction starts next week and I'm putting a quick-disconnect fitting outside where the future generator will be.

In the meantime, I plan to wire up a 50-amp inlet and breaker and get an adapter to go from the L5-30 on my generator to the L14-30 plug on the inlet. Yes I know I can't run any 220-volt stuff but I wouldn't attempt it with my little generator anyway.

I really like going the backfeed route because I was limited to 10 circuits with the transfer switch. I have a lot of circuits that don't have a lot of draw. All the lights in the house are LED and most receptacles aren't in use until I turn something on. I like the idea of being able to pick and choose from all of the circuits.

I now have another question: what's the proper (code compliant) way to run the cable from the service panel out to an inlet box on the side of my house? I know 6-gauge wire for the 50-amp inlet and breaker. I need to poke through the side of the house (through wood - accessible from the basement near the panel) and mount the inlet box. The inlet would literally be on the other side of the wall from the service panel. Do I need conduit? Can I just flush mount the box on the side of the house and poke the wires through the back?
 
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Old 04-11-16, 08:51 AM
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I'd need to move 10 breakers down 2 positions
Nah, just move 2 breakers down 12 positions. You don't need to maintain them in order. You can extend the wires with wirenuts if they don't reach to the bottom of the panel.

what's the proper (code compliant) way to run the cable from the service panel out to an inlet box on the side of my house?
Same as if you were running a receptacle or anything else. Poke the cable through into the outdoor rated box. Make sure everything is sealed up with caulk and/or foam. You can use a short length of the conduit through the wall if you want, but it is not strictly required.
 
  #6  
Old 04-11-16, 09:17 AM
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Of course - move the top 2 down 12 positions. I definitely need to extend the wire for those top 2 breakers though but that's easy enough to do, like you said, with a couple of wire nuts.

Thanks!
 
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