Getting the most out of a transfer switch & generator

11 years ago

Hi,

I have a 10,500 starting, 7,500 running generator and a reliance 10 circuit transfer switch that was professionally installed and working properly.

My question is can I (meaning a professional electrician) add more circuits (lights and outlets mostly) to the transfer switch? right now all the switch wires are connected to the electrical box. Can an electrician splice and/or add more circuits to the transfer switch?

On the 110v switches I currently have lights/outlets on a couple switches; my microwave has its own switch, fridge and 2 outlets on another switch. As far as the 220v switches go, I have 2 baseboard heat units connected, and my water pump.

What I really wanted is my water pump and water heater connected on the two 220v switches if thatÃ¯Â¿Â½s possible to do? And can I add more lights/outlets to already wired 110v transfer switches?

I ultimately want my generator to run as much of the house as possible. I am not even coming close to half capacity on my generator. My current generator usage is only 25-30% when on gen. power. (I know this due to LCD panel on generator) with everything running except the baseboard heating.

Water pump, fridge, microwave do not run all the time as you know. With everything listed above and two baseboard heating units on 80 degrees, the generator runs at 60%. I would give up my baseboard heating for the water pump, and just get a portable electric heater to warm us up instead while on generator power)

What is the amps on a water eater, and i think min s 30A. Is there a way to convert 30 amps to work on my Reliance transfer switch? Or is there a way to directly plug in the water heater to the generator or something similar to this setup so I can have the water heater also working when the power is out?

Thanks so much for the help with all of this!!

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Comments (4)

Ron Natalie
11 years ago
An electric water heater? Depends on the size. I've seen little ones that have 20A plugs on them. If it requires a 30A circuit, you're not going to get it on that transfer switch.

The problem is the transfer switch can only switch branch circuits. Since you're stuck at a half a dozen 120 branch circuits, you need to be selective in which ones you put on the switch. You might be able to move around some loads on your main panel to get the ones you want on the switch.

A 30A hwh is going to chew up almost that entire generator (and already exceeds the capacity of that poor reliance panel which is only 20A anyhow).

My suggestion would be to put a propane HWH (Or natural gas if available in your area). My Rinnai tankless will run fine with only a half an amp or so of power to power it's control circuits. Much less than it takes to run my well pump.
ionized_gw
11 years ago
Is this an automatic transfer switch or a manual one?

You can run pretty much anything you want with that generator, but only one at a time, sort of. Resistance heating of air or water takes a lot of power. Big motors take a lot of power to start up. Motors will easily take up twice the running current in starting. Look at your meters when your pump triggers and see what happens!

As an illustration, you can sometimes start up a big load and then when it settles down, add smaller loads that would be too much while staring a pump. This really does not apply to your case, however, since the water pump will be on and off a lot.

Ronnatalie is right, if you want to run all of that suff seamlessly, you need a bigger generator, much bigger. If you want to be selective and run large loads, like the water heater and pump, one at a time, install a manual transfer switch and use the circuit breakers to turn everything else off.
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Usually, jargon from a technical field is unintelligible to people outside of that field. that is bad enough and is often avoidable. In this case, the jargon is misleading. That makes it unusual. Now, if everyone would call it "split phase 120/240" or something like that instead of single-phase, it would be much more satisfying. What makes it really frustrating is that when I have asked, probably a dozen or more times over so many years, why typical residential power is not two-phase, I get dismissive answers. Maybe the answers came mostly from people that I thought would understand more than I do, but really don't and don't want to admit it. I just thought of another point for the philosopher-engineers to critique as I re-read the previous posts. I have single phase power at my house (well, most people do) when connected to the POCO. That is because the power originates from a single winding on a generator. When the power goes off and I fire up my back-up generator, I have is two-phase. Is that correct?
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I would suggest just installing a 400 amp manual, non-fused, service entrance rated transfer switch with an inlet to plug your generator into. This way, you will be able to power your entire interior panel and have the luxury of using any circuit that you need. If the only objective here were to service the house main panel (interior panel?), I'd have no qualms with this approach, but it doesn't address the two-service configuration. [Also, assuming the remote house disconnect is fused at 200A, then a lower-rated transfer switch (e.g., 200A) could be used below the disconnect. Note that the OP still hasn't confirmed that the disconnect is fused, but I think he's implying that. It makes sense that it'd be fused in order to protect the 4-ought AL wire feeding the house.] **** If, as is likely, that water pump in the barn is 220V, the simple 120V extension cord option for the barn doesn't appear to be a viable option so, yes, I think you're looking at a two-transfer switch design of some sort. My hunch is that any kind of single switch designed to handle two services would put you into some really pricey industrial hardware, so it's probably a case of "two is cheaper than one". To further flesh out Option #2, you could consider installing a j-box with a 120/240V generator inlet spliced to two ouput feeds--one to each transfer switch, located immediately downstream of the discos. What remains to be vetted, to my way of thinking, is the issue of how the grounding system works with that three-wire feeder. I hope that one of the double-E's here comes along to weigh in on that because I don't feel qualified to give you a confident recommendation about how to bond (or not bond) at the generator itself.
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weedmeister
11 years ago
My friend does something similar. However, his generator is connected directly to the main panel through a manual interloc/transfer switch. So when the power goes out, he goes to the panel, operates the interlock, turns off loads he does not need, starts the generator, then switches it into the panel.

Since the HWH is already hot, he turns that off. He turns it on when he needs it, but sheds other loads (pump, kitchen stuff, etc) for the 30 minutes it takes to heat up the water.
ionized_gw
11 years ago
What I will probably do in planning a generator installation is have an ATS to run the refrig and freezer alone. Maybe run nothing else but I have to think about pipe heaters and heat to keep the pipes from freezing in the rare freezing event here. That is all I really care about if I am not home.

Then I will probably have it arranged so I can disconnect from the ATS and use a manual transfer switch enabling me to select additional loads. I will want enough capacity to run a couple of mini splits, but I have proven that 6500 W is enough to keep the food cold and run those.

It may be that is not much less expensive than a bigger genset to run the whole house. I'll just have to get estimates when the time comes.

Getting the most out of a transfer switch & generator

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Ron Natalie

ionized_gw

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weedmeister

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