Electrical Question - Transfer switches

[BrianC636]

Gentlemen (and ladies too I guess) I need some input on how I can wire up my shop, then house with a new whole house generator. The wife wants to prepare for the worst storm ever and still be able to do whatever she wants in the process.

I’m in the process of wiring up my new shop (40 x 64) and can’t figure how I should wire in the transfer switch for the generator. Here is what I have.

400 amp meter socket (Milbank U5067-X-2/200) with 2 built in 200 amp breakers. One for the shop and one to run to the house once I get it started. The socket (not hooked up yet) is wired from the meter to those breakers then off to whatever it is they power (all in the same enclosure). My question is, am I going to have to run 2 manual transfer switches (I don’t want automatic) or can I unhook those 2 breakers and run the meter to my transfer switch (400 amp switch) then back to those breakers to feed their sources?

I currently still have a clean slate to work with since nothing has been installed I just want to do it the right way the first time. The only hang up I have is the location I want to mount everything. I have about 4’ wide and about 50” tall worth of space I’d like to make everything fit into if possible.

Suggestions?

Thanks,

Brian

 

[Docholiday]

Gentlemen (and ladies too I guess) I need some input on how I can wire up my shop, then house with a new whole house generator. The wife wants to prepare for the worst storm ever and still be able to do whatever she wants in the process.

I’m in the process of wiring up my new shop (40 x 64) and can’t figure how I should wire in the transfer switch for the generator. Here is what I have.

400 amp meter socket (Milbank U5067-X-2/200) with 2 built in 200 amp breakers. One for the shop and one to run to the house once I get it started. The socket (not hooked up yet) is wired from the meter to those breakers then off to whatever it is they power (all in the same enclosure). My question is, am I going to have to run 2 manual transfer switches (I don’t want automatic) or can I unhook those 2 breakers and run the meter to my transfer switch (400 amp switch) then back to those breakers to feed their sources?

I currently still have a clean slate to work with since nothing has been installed I just want to do it the right way the first time. The only hang up I have is the location I want to mount everything. I have about 4’ wide and about 50” tall worth of space I’d like to make everything fit into if possible.

Suggestions?

Thanks,

Brian

Need to know what u want to run off the gen.

 

[Jagmandave]

I would think you could go meter to transfer switch to breakers to load panels.

The transfer switch will isolate the line power so you won't backfeed into the grid.

Right, electrical guys?

That way your genset will feed your entire house and shop, and you can turn off various breakers on your load panels to make sure you don't overload the generator, unless your genset is big enough to carry all the load.....

 

[BrianC636]

The wife said she doesn't care what the generator cost but wants one large enough (30kw or so) to run our entire house and most of the shop.

 

[pattenp]

There are transfer switches that you have to pick and choose what circuits you want powered off the gen and then there are switches that transfer the whole house. I'd think you'd want the whole house style to switch over everything, including the shop. Be prepared to paid around $2000 for a 400A transfer switch. Plus I don't think you can get a manual 400A transfer switch, I think they only come as auto. Whoever you buy the gen from will set you up the best way.

 

[Speedy Petey]

The wife said she doesn't care what the generator cost but wants one large enough (30kw or so) to run our entire house and most of the shop.

I'm sorry, but I laugh out loud whenever I see/hear this. How spoiled are we that this is THAT important?????
What is wrong with just the essentials with a few luxuries?? Jeeze!

Also, if you are thinking 30kW, think AGAIN! You're looking at 50+ kW.
Since you are going manual you can avoid the code that states the genny must be able to serve the WHOLE load if transferred automatically. If that were the case you'd be looking at 80kW. INSANE if you ask me.


If you go from the meter to the transfer the transfer switch MUST be service rated. This means it has a main breaker/fuse built in.

If it were me I'd go with a 200A automatic switch and only do the house. Then you can get away with around a 30kW unit.
Do you REALLY need your shop for the rare times power will be out for more than a few hours??

 

[pattenp]

Speedy, that is a very smart suggestion. I get by with no problems using a 8000W portable gen on a manual switch. As long as I got TV and the frig runs I can tough it out for several days without power. I just tell the wife to **** it up.

 

[BrianC636]

Yes, I have to have the shop since that is where the power for the well comes from. The meter socket I have has 2 200A breakers in it already so it sounds like I'm going to have to run 2 switches. The shop can probably get away with a smaller manual switch for the "must haves" and the 200A going to the house.

 

[PRH44]

Speedy raises a very good point as it relates to your service entrance conductors. The conductors or bus between the meter and the Main breaker. Not only does this transfer switch need to be service rated and have a main breaker.
The transfer switch will need to be a full 200 amp rated switch= $
You will also need to get approval from your power company.
like pattenp and Speedy have stated. you can get by with far less and still run a lot of equipment.
I use an 8KW with a manual switch also. I can run virtually anything in the house as long as I load manage.
Lights, fridge water pump, sump pump no problem If I want hot water turn some things off good to go. I can use the range just manage the load.

 

[BrianC636]

Good point. The smallest manual switch I can run is 100A. My electric company has a list of approved switches that can use. I may just run 2 smaller ones and let the wife deal with it. Thanks guys.

Brian

 

[nehog]

The wife said she doesn't care what the generator cost but wants one large enough (30kw or so) to run our entire house and most of the shop.

You need professional help... (Uh, not that way, but an electrician who knows generator setups...)

First, a generator that is too large can result in other problems, including very high operating costs, and if diesel it can do things like wet stack. Be careful about over-sizing a generator. I doubt very much you can use more than 15-20 KW maximum at one time--you are not a business with fixed electrical usage, a house's usage goes from near zero to maximum and back constantly as things switch on and off.

Your generator expert/electrician can clarify you as to the code issues re: multiple transfer switches. I think (big think, I'm not going to try to look it up) you can't have multiple transfer switches wired the way you plan, however it may be a gray area.

BTW, a 400 amp transfer switch and a 30 KW generator is not going to be cheap--one hopes your wife has the money stashed away somewhere.

(BTW, my full electric house, with electric heat, in NH, with a big shop, can easily be powered by a 15 KW generator.)

 

[koditten]

That problem with the well power supply at the shop is going to be a toughy. Prolly call a specialized company that does standby generators.

My 16k runs my entire house, including the central air. I had to draw the line at supplying the shop tho. I really couldn't see myself running welders and air compressors during an extended outage anyways.

I researched on doing it myself as well. I found out that a complete, pro installed unit was only a few hundred more. It was a no brainer on my part.

If it was me, I would have the house with a standby unit, and have a dedicated portable genny for the well pump at the shop. Just please get a decent manual disconnect for the shop.

You don't have to run the shop genny constantly, just long enough to get the house thru shower time anyways.

 

[jeff000]

Just run the well power to the house panel.

Most everything else has been covered. Best bet is to have someone go and look at what you have, too much gets missed in explaining over of the internet.

 

[theoldwizard1]

My suggestion.

Return the meter socket and get one with a single outlet with no breaker. Run that into a 400A rated panel box. Make certain to buy a panel box that has a built in generator interlock. (Info on an aftermarket interlock. Most panel manufacturers offer an interlock option on at least some of their product line.) No other transfer switch is required !

Feed the shop from this panel box through a separate 200A breaker. Clean. Simple.

30KW should run your home A/C and the well pump and probably everything in your shop at the same time (well, maybe not your welder/plasma cutter).

 

[theoldwizard1]

First, a generator that is too large can result in other problems, including very high operating costs, and if diesel it can do things like wet stack. Be careful about over-sizing a generator. I doubt very much you can use more than 15-20 KW maximum at one time

I have to agree with everything he said ! Bigger is NOT better always better when it come to generators.

Add up your heavy load items in the house; A/C, refrigerators/freezer, water heater, stove, dryer, etc. Don't forget the well pump which is technically wired to the shop power. If you are just building, get a gas water heater, stove and dryer and those won't be on the list.

If you cover the major appliance (including the well pump) with a 10-20% cushion, you should be golden. Worst case is you won't be able to weld with the A/C on in the house during a blackout ! If that is unacceptable, go buy a 5-8KW portable generator for use with shop tools.

 

[theoldwizard1]

Something else I just thought about. Are you going to run your generator off of propane or natural gas ?

If propane, you might want a separate tank or at least one larger than you had planned.

If natural gas, you need to do some research quick and find out the flow requirements for your chosen generator. You may need a bigger diameter feed line coming from the main to your house. You probably WILL need a larger meter/regulator !

 

[mrb]

i would just install two 200a transfer switches. Two of something 200 amps is usually quite a bit cheaper than one of something 400 amps whether its a transfer switch or a main breaker panel

 

[Jagmandave]

I have a 12,500 watt genset, and I can't envision that not being enough for our household needs even in the dead of winter, although summer might be a bit marginal between the A/C and two fridges.

 

[RECox286]

We took care of a vacation home where the new owner removed a 13.5kw self

contained coleman style gen in favor of a 70kw genset powered by a Ford diesel fed

from a 2" natural gas line. The first time that I was in the house, and the darned thing

fired off to self prove, I thought the house was hit by a semi truck or an airplane.

It really rumbled ! Had an induction system piped in from outside the garage, and the

cooing fan sucked the flood gates on the garage doors to full open.

Owner told us his company wouldn't allow an electrical failure to put him out of reach

any time night or day, nor render his computer down. Sold the home 3 years after

buying it, for a cool 5 mil.

Uncle Bob

 

[mm08822]

Consider refeeding the well from the house panel. If you do, the entire job gets real simple. Rent a ditchwitch and refeed the well.

 

[Alchymist]

We took care of a vacation home where the new owner removed a 13.5kw self

contained coleman style gen in favor of a 70kw genset powered by a Ford diesel fed

from a 2" natural gas line. The first time that I was in the house, and the darned thing

fired off to self prove, I thought the house was hit by a semi truck or an airplane.

It really rumbled ! Had an induction system piped in from outside the garage, and the

cooing fan sucked the flood gates on the garage doors to full open.

Owner told us his company wouldn't allow an electrical failure to put him out of reach

any time night or day, nor render his computer down. Sold the home 3 years after

buying it, for a cool 5 mil.

Uncle Bob

Man, that must have been some setup - a diesel running on natural gas! I'd like to have seen that!

 

[theoldwizard1]

Man, that must have been some setup - a diesel running on natural gas! I'd like to have seen that!

It can and is being done. Complicated as hell because the heat of compression will not light the natural gas so a small amount of diesel is inject near TDC. That flame starts the NG.

This is all fairly new technology.

 

[Speedy Petey]

We took care of a vacation home where the new owner removed a 13.5kw self

contained coleman style gen in favor of a 70kw genset powered by a Ford diesel fed
.................

Sold the home 3 years after

buying it, for a cool 5 mil.

Anyone who can afford a $5m vaca home in south Jersey is not worried about cost, and is NOT DIY'ing their generator.

 

[theoldwizard1]

Link for Square D QO load center generator interlock.

Less than $50.

Down side is that the max main breaker for a QO load center is 225 Amps. Max branch circuit (for feed to shop as well as feed from generator) is 125 Amps. 125 Amps at 240 Volts is 30KW.

 

[thammel]

Heck, my 7.5kw Winco gen running off propane is fine for my 3000 square foot house with well pump. Unless you need to power a heat pump or A/C, this size would be fine.

Tom

 

[Speedy Petey]

Link for Square D QO load center generator interlock.

Less than $50.

If you are buying those for LESS than $50 buy a few extra next time and send them to me.

 

[nehog]

If you are buying those for LESS than $50 buy a few extra next time and send them to me.

The lockout is (IIRC) about $50... They are not expensive, a few pieces of stamped sheet metal and some screws. They are made for many different types and makes of boxes, not just SquareD ones.

 

[foolishpride]

The lockout is (IIRC) about $50... They are not expensive, a few pieces of stamped sheet metal and some screws. They are made for many different types and makes of boxes, not just SquareD ones.

Looks like they are about $150.

http://www.interlockkit.com/squareDmain01.htm

 

[Speedy Petey]

The lockout is (IIRC) about $50... They are not expensive, a few pieces of stamped sheet metal and some screws. They are made for many different types and makes of boxes, not just SquareD ones.

I am well aware of what a lock-out is, but I have yet to see one less than $75 and typically they are around $150, for those two pieces of stamped steel.

Funny how the factory SqD stuff is much less than the others. Kind of backward to other stuff.

 

[Morrisman]

The wife said she doesn't care what the generator cost but wants one large enough (30kw or so) to run our entire house and most of the shop.

Probably because she won't be the one paying for it.

Like the other guys say, does she really need her air-cons, curling tongs and heated toilet seat in the immediate aftermath of The Perfect Storm, or is it wiser to simply run the essentials, such as lights, refrigerator, water pump etc.

Remember, you may we be surrounded by hoards of people who have nothing, no backup plan, so don't advertise that you are living life unaware the rest of the county is blacked out.

 

[nehog]

Once again, I smell the sweet smell of business opportunity. Take about $5 worth of materials, and produce a product that will undercut the competition at $50.

(Before any screams: "This guy knows nothing about starting a company..." yes, I've been there, done that several times. I make a big chunk of my income from just such an enterprise right now. So if these things are $150 right now, the field is ripe for a new player to bring reality to the game.)

 

[mrb]

Once again, I smell the sweet smell of business opportunity. Take about $5 worth of materials, and produce a product that will undercut the competition at $50.

(Before any screams: "This guy knows nothing about starting a company..." yes, I've been there, done that several times. I make a big chunk of my income from just such an enterprise right now. So if these things are $150 right now, the field is ripe for a new player to bring reality to the game.)

UL and product liability insurance make that $5 part cost $50. Most such items retail at 3x cost, so there you go.....$150

 

[BrianC636]

Probably because she won't be the one paying for it.

Actually, she is. She's my suga-momma.


We save all of my income and live off of hers.

After more research, we've decided to put a transfer switch in the house and one in the shop. My electric co-op has a list of approved disconnect switches and says it requires positive disconnect from their system before supplying gen power. I don't think they'd buy off of on the interlock system.

 

[theoldwizard1]

After more research, we've decided to put a transfer switch in the house and one in the shop. My electric co-op has a list of approved disconnect switches and says it requires positive disconnect from their system before supplying gen power. I don't think they'd buy off of on the interlock system.

Why would they NOT approve of a system that does EXACTLY that ! I would stick with an interlock from the panel manufacturer (as opposed to a 3rd party), but I guarantee they pass all national and local electrical codes. Anyone saying otherwise is just not educated.

Do what you want, it is her money anyway.

 

[Aceman]

Why would they NOT approve of a system that does EXACTLY that ! I would stick with an interlock from the panel manufacturer (as opposed to a 3rd party), but I guarantee they pass all national and local electrical codes. Anyone saying otherwise is just not educated.

The co-op can approve or disapprove whatever they want. If they don't approve of a generator interlock, they don't have to supply you with power. Simple as that.

 

[theoldwizard1]

The co-op can approve or disapprove whatever they want. If they don't approve of a generator interlock, they don't have to supply you with power. Simple as that.

Not true. They have to report to the state, typically Public Service Commission. It a device meets all codes, they can't refuse to provide service.



My buddy got tired of the lights going out in his subdivision every time the wind blew because the power company was not maintaining the lines leading to his subdivision. A couple of phone calls to the Public Service Commission just before a hearing to approve a rate increase and man those trees were trimmed in record time.

 

[BrianC636]

The co-op can approve or disapprove whatever they want. If they don't approve of a generator interlock, they don't have to supply you with power. Simple as that.

Aceman is correct. Here locally at least on new construction, they inspect EVERYTHING prior to you signing off on it. The county we live in is crazy on how many inspections they require but we have the highest housing value around this area.

For my pole barn project alone, I have like 12 inspections.

They inpected the staked out shop, pad, plumbing in the concrete, footings, rebar, electrical rough in, plumbing rough in (in the wall), electrical box and meter socket.

After that they still have to come out and do a final inspection before I can use the shop.


Sounds fun huh?