Whole house generator install without a transfer switch - Power Equipment Forum : Power Equipment Forums
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post #1 of 13 (permalink) Old 01-07-2020, 06:22 PM Thread Starter
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Whole house generator install without a transfer switch

Hello,
I have a 22KW General generator (70422) I am planning on using without a transfer switch. I have wired up my 200 amp panels with mechanical interrupts so the generator can't be tied to the power company. Because I am not using a transfer switch I will have to go out and manually start the generator when the power goes out. Once the generator is running and supplying power I can go back to my panels and operate the mechanical interrupts to turn off the main preakers and then turn on the generator breaker to the panel. I am havig an issue with the wiring. The main 2-2-2-4 wire is self explanitory for where it hooks up. I am having a problem with the charging for the battery. I see where the blue terminal is for fused 120 VAC for battery charger. Can I just run the 120VAC hot lead to this terminal and hook the ground and neutral wies to their respective points?
I did call General and asked about the battery charger wiring and they told me their policy is that all of their generaors needed to operate with an Automatic Transfer Switch. I suppose that would be great if I could use the switch but my circumstances will not work for the switch.
Lemmeno what you think about powering up thw battery charger without the transfer switch.
Thanks
John
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post #2 of 13 (permalink) Old 01-07-2020, 07:01 PM
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Welcome to the forum.

That Generac G007042-2 22kW Generator is a VERY nice unit.

The 57 Page Installation Guidelines have LOTS of safety instructions, for hazard protection. My very strong suggestion is to fully comply with all the requirements.

It sounds like the existing installation has a manual transfer switch instead of an automatic transfer switch. Is that correct?

If correct, then the wiring could be implemented the same, it just wouldn't transfer as described.

The previously linked wiring diagram, looks like the battery charger is part of the Main Controller board. If correct, then city power would be charging the 12VDC battery when available and the generator would be charging during operation.
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post #3 of 13 (permalink) Old 01-07-2020, 07:38 PM Thread Starter
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Wingless,
I looked throught the manual and the warnings. They all make sense and I am not violating any of them.
I do not have a transfer switch. I have two 200 amp panels that are fitted with a mechanical interlock. The generator enters the box through a 100 amp breaker that is controlled by the interlock. The main breaker OR the 100 amp breaker can be on but the interlock will not allow both. I installed this circuit with an electrical permit.
I am looking for some help wiring up the battery charger. Since I am not using the ATS I will have to wire in some source of 120VAC to run the battery charger. I think the fix is to laythe hot wire on the blue T1 block and then run the neutral and ground to the neutral bar. Look on page 30 of the manual. I am asking if anyone has done this. Thanks
John
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post #4 of 13 (permalink) Old 01-07-2020, 09:00 PM
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According to the previously-linked manual and the wiring diagram, on the Sense Wire Terminal Block, the blue T1 120VAC LOAD SUPPLY is an input to the Main Controller Board. It is labelled: "Fused 120VAC for battery charger". The N1 and the N2 240VAC Utility Sense are also inputs to the Main Controller Board.

As previously stated, it looks like the battery charger is on that Main Controller Board.

My read on those instructions are to connect that Blue T1 to a breaker on the main circuit panel, to provide street power to the generator Main Controller Board, for it to power the battery charger.

Neutral and ground already exist from the rest of the generator wiring.
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post #5 of 13 (permalink) Old 01-08-2020, 02:01 PM Thread Starter
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Wingless,
Are you saying the battery charger circuit resides in the Transfer switch or in the Generator? I don't see what you are seeing in the manual. If the charging circuit is in the generator wouldn't it need the 120 VAC on T1 to power it up? If the battery circuit is in the ATS why would the 120 VAC need to come over from the generator? Wouldn't it come from the ATS?
I have to figure this out so Idon't hurt the circutry and I really don't want to but a transfer switch I can't use.
Thanks
John
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post #6 of 13 (permalink) Old 01-08-2020, 09:08 PM
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The manual does not define the battery charger location.

My analysis of the documentation leads me to conclude that the Blue T1 120VAC feed from the main panel (street power) is used as the power source for the generator's Main Controller Board battery charger, residing as part of that Main Controller Board.

Examine page 5 of 6 of the wiring diagram. The 12VDC battery is in the lower left corner. The generator Main Controller Board is in the center. That board is connected to the battery minus terminal with the 0 wire and to the battery plus terminal with the 13 wire. IMO, the battery charger HAS to be on that generator Main Controller Board.

My read of that documentation is to provide a 120VAC from the main circuit panel, either a 15A or a 20A properly-wired circuit would be fine.

The only thing that jumps out to me as a concern are the two yellow N1 and N2 utility sense wires. My read is those get wired to the street side of the transfer switch, to provide utility sense for the generator. How is fault protection provided to those two wires? Do those two wires require a small circuit breaker box to provide over current protection on those two sense wires?

WRT the ATS, the generator Main Controller Board has a three wire output connection w/ the 0 wire, 12VDC ground, the 194 wire, a +12VDC connection and the 23 wire, for the transfer actuation control.

IMO and ATS is not required, but the generator logic must somehow be configured for a manual mechanical interlock transfer, instead of the intended automated transfer.
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post #7 of 13 (permalink) Old 01-08-2020, 10:34 PM
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OK, I'm a lazy old man and before I tried to work around the built in logic to use the device in a way it wasn't intended, I'd just ignore it. Get a battery charger/maintainer and connect to the battery. Disconnect the wiring from the charger in the unit. Feed the charger with 120 volts, preferably from a dedicated breaker. Verify that you can start and stop the unit. The battery is kept charged, you can go out and start it. This may allow you to "imagineer" around the base design. By not feeding the generator with a constant 120VAC the automatic exercise, etc. won't be enabled, it'll just sit there in off until you start it-provided Generac doesn't have any more logic surprises built in.

Here's a charger/maintainer I grabbed at random at Amazon, there's tons of them out there.




Good luck
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post #8 of 13 (permalink) Old 01-09-2020, 08:32 AM
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Without looking at the drawings (disclaimer)... Usually, the sense leads come from a commercial-side breaker or fuse panel.

As for the engine battery, I agree with @exmar in that you're over thinking it. I believe a low-cost, regulated charger could be directly attached without causing a problem. Basically, it would be the same as if you needed to 'jump start' it.
Just make sure the charger has some sort of built-in regulation / overcharge protection.
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post #9 of 13 (permalink) Old 01-09-2020, 02:01 PM
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According to the previously linked Owner's Manual, page 15 shows operation of the front panel AUTO / OFF / MANUAL control.

That operates just as expected.

Pressing the OFF button has this result: "Shuts down engine and prevents automatic operation of unit."

That is probably the best option for a system w/ a manual mechanical interlock transfer switch.

The only other point is to ensure manual periodic operation for system maintenance.
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post #10 of 13 (permalink) Old 01-12-2020, 10:26 PM
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The manual system is OK, but can you wife operate the necessary devises when you are away?
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