Mac
This isn't a Generac question, but this is one of few installation resources I have found on the web.

I picked up a used 7 kW B&S standby generator that I'd like to wire to a poultry barn. This did not come with a transfer panel, so I am looking for a transfer panel. I contacted a Briggs distributor and they said that the only recommended panel was the B&S 50 amp with integrated emergency load center. I told them that I wanted a "whole-house" transfer switch to switch the entire service and they said that they could only recommend their 50 amp emergency load center.

So I am left trying to figure out what will work on my own. This generator monitors the 240 volt utility service and upon voltage loss will autostart. Upon return of the 240 volt utility it shuts down after a five minute cool down. It has its own no-load exercise function built in. There are no communications from the generator nor any start/stop terminals to control the generator.

So, my question is whether a Briggs 100 amp "whole-house" switch (or Generac, Asco, GE, etc.) will work with this generator without communications between the generator and T/S?

I would assume upon loss of utility voltage that the generator will autostart and that once the voltage is stable the transfer switch circuitry will transfer to generator. When utility power is restored I'd assume the transfer switch will switch back under it's own control, and the generator will shutdown upon it's own cooldown timer.

Am I missing anything here? It looks like many of these generator and switch combos use RS485 serial communications, but the details about operation are sparse. What are they communicating besides start/stop functions for the generator that couldn't be controlled with simple contacts? Assuming the B&S generator can start/stop/exercise on it's own, will any automatic transfer switch take care of the rest without communicating with the generator?
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Skip Douglas SkipD
The first thing that you need to realize is that a 7 kW generator will NOT be suitable as a "whole-house" generator in an automatically switched system. The National Electrical Code requires that the generator be able to run everything that it would be automatically connected to. The NEC further requires that certain calculations be done to determine what the power demand for "everything" would be.

The only way to install your 7 kW generator with an automatic transfer switch would be to use either an ATS that has a dedicated set of breakers that are fed by either utility power or generator power (and the loads connected to these breakers add up to the generator's capacity or less) or you could have a load-shedding system to keep the possible demand within the capacity of the generator.

The Briggs distributor made the correct recommendations for valid reasons.
Skip Douglas
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Mac
It's plenty suitable for my installation. As I said, it's a poultry barn. Max load is around 6 kW, with normal operation being about 3-4 kW. All of the barn systems even step-start upon power up. I do not need load management nor an emergency load center.

The installation is not beyond me as I worked for over 20 years as a power linesman and have installed and operated multi-megawatt power generation systems. The info on theory of operation on these consumer grade systems is sparse. Most of the manuals say "wire it up and set the controls to the preferred mode of operation". Without any further info available I am asking here to see if my assumptions on device operations are correct and whether there may possibly be something I've overlooked.

If the generator can start/stop on its own by monitoring the utility service, will a typical T/S switch properly switch the loads as necessary without communicating with the generator? Is there anything I may have overlooked?
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ohmslaw
Mac,
The generac switch will not work. The Asco and GE will. Cutler hammer also has a switch that will work. You need a switch that has brains. The generac switches get there cues from the generator. That being stated I have a 50 amp Briggs switch I would love to sell you.
Tim
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Mac
Tim, thanks for mentioning Cutler Hammer as I hadn't looked at their switches. Upon looking at their website I found that Eaton sells a "Briggs Harness Kit" and has instructions for modifying their transfer switches to work with "utility sensing" generators.

[url]http://www.eaton.com/Electrical/USA/ProductsandServices/ElectricalDistribution/ATS/Contactor/index.htm[/url]

I figured the commercial switches would work, but was trying to go cheap with one of the consumer line switches. I'll probably shell out more for the T/S than I paid for the used generator.
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Mac
Well I tried posting a direct link, but you have to muck around the website to find it. Basically it's a two pole fuse block that mounts in the transfer switch and the 240 volt utility power is switched by a N.C. contact in the transfer switch allowing the transfer switch to control a utility sensing generator.
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ohmslaw
Eaton/Cutler Hammer sells a switch that will work with the Briggs. It is the same unit you can buy with an Eaton Generator which is now Generac.
You will not need to add anything to it. The sense wire fuse block is already installed.


[URL="http://www.eaton.com/Electrical/USA/ProductsandServices/Residential/GeneratorsTransferSwitches/ProductLiterature/idcplg?IdcService=GET_FILE&RevisionSelectionMethod=LatestReleased&Rendition=Primary&dDocName=IB70-8689"]http://www.eaton.com/Electrical/USA/ProductsandServices/Residential/GeneratorsTransferSwitches/ProductLiterature/idcplg?IdcService=GET_FILE&RevisionSelectionMethod=LatestReleased&Rendition=Primary&dDocName=IB70-8689[/URL]


Tim
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ohmslaw
[URL="http://www.eaton.com/Electrical/USA/ProductsandServices/Residential/GeneratorsTransferSwitches/ProductLiterature/index.htm"]http://www.eaton.com/Electrical/USA/ProductsandServices/Residential/GeneratorsTransferSwitches/ProductLiterature/index.htm[/URL]
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Mac
I found a used Cutler Hammer 100 amp "residential / light commercial" transfer switch on E-Bay. This is quite the contraption; two molded case circuit breakers with a motor operated rocker arm strapped to the handles. The seller wanted $500, but agreed on $300.

If all goes well, I should have less than $1200 in the installation.

Thanks for the help.
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Mac
I installed the 7 kW Briggs Generator and 100 amp Cutler Hammer transfer switch last week and everything works as it should.

I did install a fuse block in the transfer switch to provide utility service to the generator. I ran one leg through the N.C. side of the transfer switch's engine start relay so the transfer switch can control the generator. It works great.

Thanks again for the help.
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