100+ Amps Neutral Switching Transfer Switch

[Runaway Tractor]

Interlock would trip GFCI on truck unless you lift the ground wire....which is a whole debate thing I don't feel like touching with a 10 foot pole.

If OP wants to lift the ground then interlock is way to go.

If OP does not want to lift the ground wire to make truck work as backup power then a neutral switching transfer switch of some type is the way to go.

Yes, yes, and yes

All the electrical engineers like to talk about the "right" way to do it without having to actually deal with the implications (typical). All the engineers designed all of this equipment to not effing work while they sit in the comfort of their chair writing long memos (also typical). We the users that exist in actual reality sometimes have to play the hand we're dealt in the field.

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[Maquis]

That's seems unclear from the OP. If it's for a critical loads subpanel then why a 100A switch? PPOB can only supply 30A.

Because the transfer switch can then handle more load when on utility power. That’s exactly my setup. I have several loads that I can’t use simultaneously on backup, but don’t want that limitation on utility power.

 

[sansnom]

Interlock kits and service level switches are great suggestions, but they don't seem work for me.

• Interlock kits: grounding issue aside, my main panel is literally full. I cannot swap any to tandem breakers because all my current 120 V breakers are GFCI or GFCI/AFCI combo. No idea why the previously owner did so, but I assume there must be a good reason. So I'll need a subpanel even if I go with the interlock route.
  • I also considered meter collar, but it isn't approved by my utility (SDG&E). Not to mention that it is way too expensive.
• Service level switch: as a DIYer, I’d rather spending days relocating breakers than mess with the service entrance. Even if I were willing to, those switches are so expensive that the ABB + subpanel setup feels like better value, especially considering my main panel is full and I may need a subpanel anyway. Lastly, service level switches are bulky and can’t be (semi-)flush mounted, not aesthetically pleasing.

 

[sansnom]

Seems like nobody bothers with Nature's Generator's 125A ATS - a $599.99 ATS+subpanel combo. Is that purely because the ATS isn't UL listed (yet?)?

https://naturesgenerator.com/collec...witch/products/125a-automatic-transfer-switch

 

[sansnom]

Because the transfer switch can then handle more load when on utility power. That’s exactly my setup. I have several loads that I can’t use simultaneously on backup, but don’t want that limitation on utility power.

Which transfer switch do you have?

 

[Maquis]

Which transfer switch do you have?

It’s not UL listed.
Here’s a link to my thread on my installation.

 

[Runaway Tractor]

Interlock kits: grounding issue aside, my main panel is literally full. I cannot swap any to tandem breakers because all my current 120 V breakers are GFCI or GFCI/AFCI combo. No idea why the previously owner did so, but I assume there must be a good reason. So I'll need a subpanel even if I go with the interlock route.

Just because the previous owner did unnecessary things doesn't mean you have to keep doing those unnecessary things. There is absolutely no good reason or code requirement for every single 120v circuit everywhere to have GFCI/AFCI breakers. You can absolutely change two of the unnecessary ones to conventional tandem breakers.

Do what you will, just trying to make sure you're making informed decisions.

 

[chl]

Interlock kits and service level switches are great suggestions, but they don't seem work for me.

• Interlock kits: grounding issue aside, my main panel is literally full. I cannot swap any to tandem breakers because all my current 120 V breakers are GFCI or GFCI/AFCI combo. No idea why the previously owner did so, but I assume there must be a good reason. So I'll need a subpanel even if I go with the interlock route.
  • I also considered meter collar, but it isn't approved by my utility (SDG&E). Not to mention that it is way too expensive.
• Service level switch: as a DIYer, I’d rather spending days relocating breakers than mess with the service entrance. Even if I were willing to, those switches are so expensive that the ABB + subpanel setup feels like better value, especially considering my main panel is full and I may need a subpanel anyway. Lastly, service level switches are bulky and can’t be (semi-)flush mounted, not aesthetically pleasing.

Some panels only have certain spots suitable for tandem breakers so consult your panel's docs (can usually find them on line if don;t have a copy - sometime the sticker info on the panel door has the infor, in small print).

If the previous owner had a lot GFCI breakers maybe there was a reason for at least some of them, who knows though.

Could be that maybe it was just less trouble than putting GFCI outlets at locations that require them, anywhere near water/moisture like bathrooms, kitchen, basements, garages, outdoors, etc.

If you switch them out, gotta put GFCIs where the code requires them.

A transfer switch like the GENERAC 6853 just requires one 50A breaker in the panel and you remove all the breakers for the circuits you transfer to the switch - it is like a subpanel in that sense. Breakers that are not connected to any circuit wiring must be removed by code and replace with filler pieces, last time I checked.

good luck

 

[chl]

Update on my install (GENERAC 6853 transfer switch - without removing my old transfer switch):

Well, I tested it with the Lightning and got a ground fault.

In figuring out why I tested all the generator input box terminals for continuity and I found in the GENERAC STANDBY position (for generator input) there was 120V across the Neutral to Ground pins - popped the bulb on one of my continuity testers and popped the fuse on my other one before I realized there was juice there, lol.

I immediately knew that meant I had mixed up the neutrals inside my service panel on at least one circuit. So I put an AC voltmeter across the neutral and ground pins and by turning the breakers in the panel on one at a time, found the offending circuit.

It was quite a tangle of white neutral wires at the top of my panel but I found the circuit neutral wire that was the culprit - it was a place where two # 12 ROMEX wires entered the service panel through the same opening, which was why I got them crossed.

Only one circuit involved in the mix-up.

Switched them and all is well.

There is always something...

The wiring in block diagram form:

The fronts of the GENERAC and 200A service panel taken off to show the spaghetti:

I was glad I used the WAGO wire connectors for the neutrals which made switching in the correct one easy.

Some of those wire nuts in the box were used by the electrician who upgraded the panel to 200A from 100A in 2011, and 10 of the wire nuts connect the 10 load circuit hots to the old transfer switch (black wires). The red wires from the old transfer switch go into the GENRAC which feeds the old transfer switch either utility power or Lightning/bonded source power.

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