How the heck does a typical home transfer switch work?

What do your panels look like,. It looks like you are transferring 2 "emergency power" panels being fed. What is it doing wrong?

How about a real Gernerac model number? The part and assembly numbers on the visible nameplates don't seem to point to a particular model.

I couldn't find a model number, so how about a search by serial number?

Incidentally, you should consider labeling the cables, wires, terminals, fuses, etc.

Why two transfer switches?

Got a schematic of how you wired it? If not, trace the wires and make one.

I had no problem finding the Generac wiring diagram for one switch but nothing for two. That is why I am asking if there are 2 emergency panels. The switch itself is a garden variety DPDT "non SDS" transfer switch.

Thanks for offering suggestions and asking questions.

I didn't wire it, but I'm pretty sure this is standard stuff.

It's just typical stuff I don't know - but I'm sure it's to typical code, which means everyone wires them similarly I would think since there's no rocket science going on.

I "think" the reason for the two panels is that each panel supplies half the house, which seems to be how it works when I pull the Buss fuses.

But that's exactly why I asked if anyone knew how the TYPICAL setup works, since this has to be as typical as typical gets for such things, given it has to be to code which means everyone does it similarly.

Back to your question, I don't know what an "emergency panel" is, as there's nothing "emergency" about this. PG&E power goes out once a month out here, for about a day on average, for about 10 to 12 times a year, where this setup isn't flipping those two fist-sized solenoids automatically.

I can manually flip them, and the setup works - but not automatically - but I'm NOT asking about that - as the problem will literally scream out where it is if I only knew how these things are typically wired.

Googling for what you mean by 'emergency panel", it "seems" that what you mean by "emergency panel" is the same as what I mean by "transfer switch", where I get the name of "transfer switch" right off the boxes themselves.

In short, I "think" this is set up as typical as typical can be, which means anyone who knows how these things are set up would be able to explain it, where I get Jeff's point that I can follow the wires, but that still doesn't tell me WHAT each thing does - just where the wires go (and there are a zillion of them).

I "think" the two panels are for two sides of the house, where I "assume" one panel has one hot and one neutral, while the other panel, I assume, has another hot and another neutral.

Otherwise, why would the two panels be so exactly symmetric?

This is one panel with an emergency panel If you have 2 panels, that explains it. There do seem to be parallel PoCo conductors feeding both switches. The small wires coming up to the one on the left is the generator. If you carefully wiggle each big wire going through the big nipple to identify them on each end you can prove all of that.

Thanks for the additional questions as this pretty much has to be typical stuff - but I just have no experience with debugging transfer switches.

This is the model number of the generator, if that's what you're asking

That Generac Generator is pretty typical stuff out here, if a bit puny, which is a Generac model 09067-9 8KW (67Amps) propane generator.

Maybe the model number on this placard is ONLY for the solenoids?

This, for example, is the placard on the side of the panel inside:

And this sticker is also on the inside of the panel:

Now that's interesting! (I can call 888-922-8482 tomorrow.)

The link shows that there "should" be a transfer switch serial number!

However while looking I found covers which have slightly different cards:

I agree. But first I have to figure out what they are.

I don't know. It's got to be standard stuff. Everything has to be to code.

I suspect each box controls one hot wire, as when I pulled the Buss fuses, one side of the house turned off when the generator was running with no power coming in from PG&E.

Both boxes seem almost perfect symmetric, so I think it's just one hot for each box. But that's why I asked about a typical setup, as this must be to code.

It came with the house, and it's to code since the house has all the permits filled, and it used to work but then stopped working about a year or two ago.

What happens is that the power goes out, and then the generator turns on, but the two fist-sized solenoids don't trigger. I can trigger them manually by putting this handle which is screwed to the box into the big solenoid.

Moving that lever down in each solenoid turns the transfer switch on.

While I was looking for the serial number, I found the closest thing to a schematic, which is this placard on the inside of the cover (which has been off for a long time since the transfer switch no longer turns on automatically when the power goes out.

*ENGINE WARMUP* - Time delay to allow for engine warmup before transfer. Fixed at 15 seconds.

*TRANSFER* - Switch transfers load from utility to standby supply; occurs after standby voltage is above set levels.

*RETRANSFTER* - Time delay after utility voltage supply is above pickup level before load is transferred from standby to utility. Fixed at 6 seconds.

System will operate automatically every seven days from the time of initial setting to ensure proper operation. Consult Owner's Manual for further explanation of Transfer System operating and features. Systems shall be tested periodically on a schedule acceptable to the authority having jurisdiction, to assure maintenance in proper operating condition. Enclosure is type 1, suitable for indoor installation. When protected with 200 ampere maximum (110a rated device) or 400 ampere maximum (200a rated device), Class J, T fuses, this switch is suitable for use on a circuit capable of delivering not more than 200,000 RMS symmetrical amperes, 250 volts maximum.

When used with 200 ampere maximum circuit breaker 100 ampere device; 400 ampere maximum curcuit [sic] breaker 200 ampere device; (type G.E. TJK or Westinghouse HLC) this switch is suitable for use on a curcuit [sic] capable of delivering not more than 10,000 RMS symmetrical amperes, 250 volts maximum.

Connect utility, standby generator supply and customer load as shown.

Terminal connectors tightening torque is 50 in-pounds (100a rated device) or 250 in-pounds (200a rated device). Control wiring terminal connectors tightening torque is 11 inch-pounds. 79959 D

Don't know why I'm getting involved here - but what you have is basically 2 SPDT contactors - on in each box, that switch the incoming feed to the main panel between the line and the generator. There are two becuase you need one for each side of the line - L1 and L2

Each contactor has 2 coils. When coil 1 is energized the contactor goesd toi position 1 - when coil 2 is energized it switches to position 2.

It is (likely) controlled by generator control box via the "plastic relay" which when not energized powers the contactor to the "line" position and when energized to the "generator" position.

It is EXTREMELY unlikey for both relays , both contactors, or both of any of the fuses in the switch assemblies to have failked so I would likely start at the genset, You COULD confirm the functionality of both relays and check all the fuses first if you want, but I expect that will be wasted effort.

What genset do you have? Generac by chance??? Very high faikure rate. Start the generator and check voltage output. Likely ZERO - which means it will never transfer. Genset may need to be "flashed" if it has not been used for years. No guarantee it is salvageable but worth a try. Something you should LIKELY get a generator tech to look at.

See

for a larger panel??? Kinda mickey mouse - but possible?????

Thanks for that document:

I just found this also, but it's the wrong model number:

Same with this one, which seems to be the wrong model number:

Unfortunately, I can't find a model number for the General Transfer Switch yet, but only model numbers for the big double-fisted solenoids.

I will call Generac tomorrow though.

Hi Clare, That was a GREAT question since I just looked and it's NOT what I thought.

I always thought I had 200Amp mains service, but I looked at the mains breaker which clearly says it's a 300Amp breaker, and on that same mains panel are three separate 100 Amp circuit breakers (plus a couple of 30 Amp spares).

So the service must be 300 Amp mains service, where I looked again at the two double-fisted solenoids in the transfer switches, each of which says it's 100 Amps.

That makes sense because when the transfer panels were working, they only ran "most" of the house, in that they didn't run the pool (which is one of the 100 Amp breakers I spoke about above on the main panel).

Given that, here's what I "think" I have. o 300 Amp mains service (broken into 3 100 Amp circuits) o Transfer switch handles only 200 Amps (100 Amps per "box")

Does that sort of sound like it might make sense?

You can't possible be that stupid. This is just another one of your long rambling posts that goes on and on so you can listen to yourself.

Kindly go f*ck yourself.

That's your cue to (wrongfully as usual) call me Snit, because you just HAVE to reply.

Nope. I'm looking for the model number or name of the transfer box so I can read the docs which should have wiring and installation instructions. Not much I can offer unless I know what you have.

Methinks I found the install manual:

"Installing Automatic Generator Generac Guardian"

I did some digging and found that the only excuse for 2 transfer switches is two generators, or two different sources of backup power such as generator and solar inverter.

I hate be the bearer of bad news, but you potentially have a miswired mess. I'm fairly sure it would not pass an electrical inspection in its present form. If you have time and money, find someone with a clue and let them fix the mess. My guess(tm) is they would recommend ripping it all out and starting over with the wiring and installation.

Good luck.

Hi Clare,

You are correct the generator is a puny 8KW Generac, model 09067-9

This propane generator is so tiny that it's only capable of 67 Amps, so I'm not sure why there are two 100Amp transfer switches yet, but the house is

It used to work, but now, when the power goes out (which happens about monthly out here in the mountains), the generator kicks in automatically, but the house doesn't get the current because the double-fisted solenoids don't turn on automatically.

I have to turn the solenoids on manually, which is the problem I'm trying to debug by asking how these two 100A transfer switches typically work.

I did find the model number, just now, after climbing on a stool

This model number is hand written as Generac 79848A (DD).

Googling for that model number, it does show up on Ebay. Generac Transfer Switch 100 Amp 250 VAC One Owner Used #71340 #79848A Switch is CSA Certified for use with control module assembly #79844, #75595 and #83494

Generac Transfer Switch 100 Amp 250 VAC One Owner Used #71340 #79848A $408.45 Buy It Now 32d 16h 48m 37s, Click to see shipping cost, 30-Day Returns, eBay Money Back Guarantee Seller: sparkyinpa (13,861) 99.6%, Location: Reading, Pennsylvania, Ships to: US, Item: 153421838181 Condition: Used, Condition: This transfer switch is in good working condition was removed because the generator was upgraded. Inside is very clean. Message us for shipping quote., Model: 71340, MPN: #71340 #79848A, Brand: Generac, Rated Amperage: 100 A, Type: Automatic

There are pictures with that Ebay listing which look almost exactly the same as mine does, so I'm pretty sure that's the model number.

I kept looking and found the model number of _each_ transfer switch!

The model number of _each_ transfer switch is: 79848A

Googling for that model number finds an exact lookalike for _one_ box

Here is just one of the eight pictures of that lookalike 79848A:

That's pretty close!

The manual switch is different, and the generator is different - but it's similar, where I will go through that excellent video with my Fluke.

I checked my main panel, which is definitely 300 Amp mains service (I had always thought it was 200 amps, but it clearly has a 300 Amp main breaker, plus 3 separate 100 Amp breakers, where the house has two of them and the pool has one).

The last guy who worked on that generator is in Santa Cruz, based on the label on the outside panel, which I found buried under stuff.

This DEFINITELY WORKED so it's NOT miswired. The only problem is that the solenoids are not automatically kicking on.

Here's what SHOULD happen:

1. PG&E power goes out about monthly
2. The Generac generator automatically turns on
3. The two transfer switches should automatically turn on
4. The house should have two 100 Amps (the pool does NOT have power) [Although the generator is puny - it's only able to output 67 amps!]
5. When PG&E comes back about 24 hours later - the generator turns off
6. The transfer switch transfers the two 100 Amps back to the mains

Everything above is working EXCEPT - I have to MANUALLY flip the double-fisted solenoids.

If I switch just ONE of them, I get only half the house. If I switch the SECOND one also, then I get the full house.

So my main problem is troubleshooting why the double-fisted solenoid is not automatically turning on.

Sounds right to me.

There are TWO DPDT switches there. I am not sure why they have two but there are two ungrounded conductors going to each throw of each switch and the line side seems to be parallel from the POCO. (See that big taped up split bolt on each ungrounded conductor on the right side). He said he has two load side panels serving half the house each and I suspect that is why he needs 2 switches. Essentially they are probably 2 100a panels fed by a 200a service.

The transfer switches need to handle the full load of the down stream panels on PoCo power. You are switching two 100a feeders. BTW you will be sorry that you don't pick up the pool if your power is out in the summer.

The transfer switch needs to be sized fir the total LINE capacity, not just the genset

Your crappy genset control board is not sensing the voltage output properly, the genset voltage is below spec, or the controller is mal-adjusted. If the genset voltage does not reach a specified value it will NOT switch over. That voltage may be adjustable or the sensor may be shot,

Daughter just had to replace the control board on the heat pump on their boat because it was mis-reading the shore-power voltage by half

- reading 57 instead of 114 - preventing the compressor from running. Was a blown chip onthe board that was no longer available for replacementby Flight Systems - the only facility in North America that services the board which has been obsolete since 2015

What amp service do most people have?

I just put some chalk on the raised letters of my mains circuit breaker which showed the mains breaker to be 200 Amps (not 300 Amps as I stated prior).

There are three separate 100 Amp breakers, each going to a different panel.

So I think, at this point, that the reason for the TWO 100A Generac model

Now I just need to figure out how to debug why this two-fisted solenoid isn't switching on automatically - but it does switch on when I flip it manually.