Home Generator / Automatic Transfer Switch

[Greg O]

Price? You only need 8? Greg

[stretch]

The refrigerator should always have it's own circuit per code. Same with the furnace and water heater.

Stretch

[m Ransley]

240v takes 2 transfer panel circuits, Sumps, refrigerator, water sofener etc etc, get a clamp on amp meter and measre start up peak-surge and run load, dont guess or read the labels, measure it. Refrigerators can pull as little as 350 surge and 100 running or 1300 surge and 600 running., Surge load is critical with a gen, surge can be 8 times run load, but is usualy 4-6 times. Figure it wrong and you will ruin your gen. Even if it is a auto panel you dont want all loads comming on at the same time. You also will have 2 amp meters, you need to balance your load for max gen life. I like manual panels, I can monitor usage and balance the load. Also what brand is your generator and what is run load and peak load . Is furnace modern with a circuit board. A rough guess you could have a 50-60 Amp surge with what you mentioned Your gen may not handle it and die on startup or burn up trying. figure your startup load and run load first. Any high draw motor give it is own circuit. Your 2 - 240 v will take 4 circuits.

[m Ransley]

Each generator leg puts out 120, so balancing is important.

[Way Back Jack]

It's 15kw and the available automatic transfer switch comes in 8, 10, or 12 circuit versions.

Why would you choose a switch with 8 or 10 circuit capability if your generator supports 12?

[toller]

Cause you simply don't have more than 8 circuits you need to power during a blackout; and all the extra wiring fills up your breaker box pretty fast. I have a 6 circuit transfer switch and had trouble deciding on the 5th and

6th circuits, as I only really wanted 4.

[Way Back Jack]

OK, in your estimation, how many circuits would be typically involved in this bare-bones scenario:

Refrigerator; oil-fired furnace; well/water storage tank; water neutralizer/softener; water heater; sump-pump.

Thanx, Jack

[toller]

If the water heater is 240v, then you have 7 circuits there. All these items should be on their own circuit. Or is this a trick question? Adding one circuit for some lights and your TV gets you to 8. (I don't have a water heater, sumppump, well, or softener; so 4 was plenty for me.)

[Way Back Jack]

No trick question. I'm just stupid on these issues and trying to learn. Thanks.

Jack

[Doug Miller]

Water softener is obviously not a critical device.

No, six circuits. But two of them are 240V circuits (the water heater, and the well pump). Five if you subtract the unnecessary water softener.

That's just silly. There's no need to put each of these on its own circuit. Neither a furnace blower nor a sump pump is a particularly high-current device, so these two could share a circuit, and still have capacity left to support lights or outlets. And a water softener draws hardly any current, so it could share a 120V circuit with any of the other loads.

Lights can share a circuit with either the refrigerator or the furnace and sump pump, as long as you don't try to turn night into day.

So a more realistic count at this point is two 240V circuits:

- water heater

- well pump two 120V circuits

- oil furnace + sump pump + optional water softener + a few outlets

- refrigerator + some lights

I *hope* you mean you don't have an *electric* water heater... ;-)

No, not "stupid". Uninformed.

Ignorance can be cured, but stupidity is forever.

-- Regards, Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?

[toller]

"Way Back Jack" >>>during

Sure. We all have to learn. As someone pointed out, some well pumps are 240v and will require 2 circuits. You can check that easily by seeing it it uses a single or double breaker. (However, he was foolish to suggest putting the furnace and sumppump on the same circuit; hopefully the electrician who wired your house knew better. They, like the refrigerator, are critical appliances and need their own circuits.)

[L. M. Rappaport]

On Sun, 13 Mar 2005 22:53:23 GMT, [e-mail] (Way Back Jack) wrote (with possible editing):

Refrigerator is 120v and requires a separate circuit (NEC). Oil furnace is 120v and requires a separate circuit (NEC). Well is either 120v or 240v and requires a separate circuit (NEC). Water heater is 240v and requires a separate circuit (NEC). Sump pump is 120v and I think requires a separate circuit.

That's a total of 6 or 7 circuits and you've left nothing for lighting. If it were me, I'd have at least 2 or 3 extra circuits, so I'd be buying at least a 10 circuit switch.

FWIW, what I did here with our 18kw diesel was to add a 200 amp transfer switch and put it ahead of the entire distribution panel. The generator is protected by a dual 60 amp breaker. With no electric heat, is capable of running the entire house and often does. Your only really big additional draws are an electric oven/range and (less so) an electric dryer.

[Doug Miller]

AFAIK the NEC does not require separate circuits in *any* of those cases. Do you have a Code citation for that?

In any event... the subject was how many circuits do you need to be able to adequately power your home from a generator, in an emergency - not how many circuits are required by Code during normal operation.

-- Regards, Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?

[m Ransley]

Modern refrigerators do consume 1/4-1/3rd the power of 15 yr old units, what is important is surge load not just saying it has to have its own circuit. A modren VS DC furnace may only need 200 watts, or boiler 200 watts, and 19.5 cu.ft Sears frige 100 watts running. Sure alot of old apliances needed their own circuit as power draw was higher, new equipment often does not.

[Chris Lewis]

No code citation per-se (I'll look tonight if I remember), but the NEC does require seperate circuits for all of the above (with the possible exception of the fridge and sump pump. Older code certainly permitted fridges to be on shared circuits).

CEC has required separate circuits (with some trivial exceptions - ie: you can put an AC clock on the same circuit as a fridge) for all of the above except possibly sump pumps.

Both codes tend to require separate circuits for every electrical motor that may come on at the same time. At least for motors in the 1/4HP and up range (ie: furnace blowers), unless they're specifically approved together (ie: a furnace air blower and oil pump).

Since the "automatic transfer" equipment would be shared w.r.t. "emergency" versus "normal", "normal" use would be in violation of code _too_.

[L. M. Rappaport]

On Mon, 14 Mar 2005 15:31:10 GMT, [e-mail] (Doug Miller) wrote (with possible editing):

You're wrong. Here are some (not all) code citations:

Refrigerator is covered under 210.b1 (doesn't have to be a separate circuit, but kitchen must be) Furnace is covered under 422.12 and/or 210.63 Well pumps fall under horsepower requirement in section 430 Water Heater under 210.11 and 210.3. Sump pump is wet location so must be GFI and therefore separate, also see 210.52B(5)(G).

[zxcvbob]

You do realize the refrigerator will be just fine for a short time without power, and during an extended outage you can run it from an extension cord? The same thing goes for the sump pump. The water softener doesn't need backup electric power (after an extended power outage you might have to do a manual recharge.) So not everything you might want to use during a power outage needs to be wired to the transfer panel. It depends how hands-on you are willing to get.

If you don't want to have to do anything, put a big automatic transfer switch between the meter and the main panel and use the main panel for all the power distribution.

Best regards, Bob

[Doug Miller]

Like I said, refrigerator not required to be on a separate circuit.

Maybe I'm missing it, or maybe it's because the only Code book I have at hand at the moment is a bit old... but I don't see that. Would you mind citing the exact language from those sections?

The sump pump is not a "wet location" as defined in Article 100.

-- Regards, Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?

[Chris Lewis]

For the most part, if the person has a smallish/portable generator (say, 5500W or less), I tend to suggest that they don't bother with transfer switches and the like, and rely on (adequate!) extension cords. The only "prep" work they might wish to consider is to rewire the critical hard-wired devices (ie: furnace blowers) so that they're running off receptacles (replacement of hard wire with flexible power cord, plug and receptacle). Secondly, prepare a "hard point" for where the generator will be parked in use (stanchions/chains/padlocks[+], "rain roof" etc), and possibly a resealable hole for where the cords go through into the house.

[Never _ever_ run your generator in an enclosed space.]

Then, when you have a power failure, you just follow a schedule of what needs to be connected and for how long. For example, a fridge will probably be perfectly fine with half an hour of operation for every 6-12 hours of outage. A freezer even less. Keeping in mind the max output of the generator...

Strictly speaking, running things like furnaces off "cords" is frequently a code violation, but most inspectors will consider "emergency preparedness" to be a good reason. Just make sure that the installation is otherwise in excess of code. Eg: _adequate_ power cords - SOW cable for "appliance cord", not lamp cord, with appropriate measures to prevent damage to it.

As for "adequate extension cords", anything but smallish loads should be fed with heavy duty extension cords. Eg: consider 12ga "contractor grade"/"building site" cords[*] as your _minimum_.

[+] There's a special place in hell reserved for those who steal emergency equipment during an emergency. _Especially_ from emergency measures organizations. During the "great" ice storm, we actually had people stealing generators from hospitals and road maintenance depots. [*] The brightly coloured fat and expensive ones. Often rated "SOW" or better.

[HorneTD]

Double pole, double throw, center off switches; that are suitable for use as transfer switches for individual loads; are readily available and when wired to a flanged inlet they make a fully code compliant way to run a furnace from a portable generator.

-- Tom H