25kw Generator Hookup

[pcpro15]

Alright, My buddy is attempting to "rig" up a PTO generator hookup at his house. While I don't know much about AC, I think I know enough to determine when something doesn't feel right.

The setup...

200amp service in to a outside panel located on a telephone pole. Inside are 100 amp service for house, 100 amp service for the new shop.

The Goal...

To be able to run the generator in the shop so the noise isn't right near the house. Have a little power for the shop to tinker around (shop lights, etc), but mostly to service the house.

The problem

He wants to backfeed the system through the shop panel and kill the 200 main breaker on the pole which in theory would work, but I know it is a big no-no. Ideally i'd like to come up with the most logical and cost effective way to set this up so no one gets hurt

The panel on the pole does not have to exist anymore if that makes it easier, but there would still need to be a way to split the 200 amp to 100house/100shop.

Again, the generator is primarly for the house. The part I am lost on is whether a 25kw generator that says it is rated at 100amp, but I guess we need to make sure it has a "full power" plug

The Solution...

I was thinking of suggesting a 200 amp generator switch between the meter and the panel. Then Run a line from the transfer switch to the shop to make it a done deal? Thing is.. those transfer switches are expensive at 200 amp. It should be a manual switch too.

Downside... you won't know when the power does come back on. Also the only reason you would need a 200amp transfer switch is because of the incoming service. The other problem is we would need to have the power cut, and the power turned back on again to install the switch.

Solution 2

If the disconnect was in the basement of the house, it would only need to be 100amp, but then you'd have to run a cable from the house down to the shop for the generator. This does take care of the primary concern, and has a cheaper disconnect, but... doesn't take care of the shop.

I'd assume there would be 120 spots on the generator too which could provide any power, but that would still leave the shop lights.

As you can see I did put some thought into this. I'd like to see what you guys think / suggest. All thoughtful suggestions are appreciated!

 

[mrb]

install generator at shop. run generator feeder directly from shop to house. Install backfeed breaker with proper mechanical interlock in the house panel and in the shop panel.

this needs to be done by someone who knows what theyre doing. Its one of those if you have to ask you shouldnt be doing it things.

 

[rkevins]

Install a transfer switch below the meter base at the pole, this may be the only legal place the utility will allow it to be to run both the house and shop, to tell when the power comes back on install a light that feeds from the power company side of the transfer switch (when the light comes back on the power is back on ) I know the tractor running the genset is loud we use them for many years before installing a 65kw diesel unit here on the farm. The main thing is you want to be safe..And remember you can run a lot off a 25kw if you don't let everything start at the same time.

 

[pcpro15]

install generator at shop. run generator feeder directly from shop to house. Install backfeed breaker with proper mechanical interlock in the house panel and in the shop panel.

this needs to be done by someone who knows what theyre doing. Its one of those if you have to ask you shouldnt be doing it things.

I hear you loud and clear on the last part. The guy doing the work is a friend of his, so it will be done however he asks him to do it. I am just trying to shove in the right direction. Hopefully my efforts are worth while.

As far as your suggestion, I follow for the most part. The part I can't process is if you feed to the house using a back feed breaker, and you kill the main feed, how does this feed back to the shop? Or are you suggesting two back feed breakers, one for each panel. House functions with full load socket, and hopefully a spare socket on the generator you could back feed the shop panel even if it is only 50amp? I need to find out what generator he is planning on buying.

Edit

What size wire would you need for that run would you think? I said about 200 on paper, call it 225. Lets make it 250 length just to be safe, and able to handle 100 amp. What wire would you use?

 

[pcpro15]

Install a transfer switch below the meter base at the pole, this may be the only legal place the utility will allow it to be to run both the house and shop, to tell when the power comes back on install a light that feeds from the power company side of the transfer switch (when the light comes back on the power is back on ) I know the tractor running the genset is loud we use them for many years before installing a 65kw diesel unit here on the farm. The main thing is you want to be safe..And remember you can run a lot off a 25kw if you don't let everything start at the same time.

I wouldn't imagine it is a requirement that it would have to be at that pole vs anywhere else really. This is at a farm, and all the lines come down the long drive on poles. The panel was put out there years and years ago for something. I forget what he told me, but they haven't used it in a long time. The thing that scares me the most is that old farm house panel in the basement I think 25kw will be more than plenty like you said.

I honestly thought about the light earlier, but figured if you wired it into the elec. co side, it would be lit all the time. Then I thought switch... but then who is going to remember if it is in the right position lol. Then again, if I follow the above posters suggestions with the interlocks (I like that), then the pole panel would still be live, so you could just run an extension cord and plug in a lamp at the house if need be lol. Either way, that is a minor technicality.

 

[mrb]

i dont know what a full load socket is.

someone needs to consult a professional on this. you may need to switch the neutral in the arrangement i mentioned which would preclude you from using breakers and would require a transfer switch.

and yes I was mentioning two transfer switches, with a feeder from the generator to the house and a transfer switch at the house. Saves a bunch of cost and wire.

 

[mrb]

pole panel still live? you mean pole panel still connected to utility?

 

[pcpro15]

pole panel still live? you mean pole panel still connected to utility?

Yep that is what I ment, I need to chose my wording more carefully

 

[pcpro15]

i dont know what a full load socket is.

someone needs to consult a professional on this. you may need to switch the neutral in the arrangement i mentioned which would preclude you from using breakers and would require a transfer switch.

and yes I was mentioning two transfer switches, with a feeder from the generator to the house and a transfer switch at the house. Saves a bunch of cost and wire.

Full load socket = one socket to give all of the power. Most other generators that I see that don't have this socket only give 50amps on the 240 connection.

Use this one for example, its one of the bullets.
http://jayhawkgeneratorsupply.com/i...n=com_virtuemart&Itemid=96&vmcchk=1&Itemid=96

I do appreciate your concern for suggesting to call a professional, but that is what you are for . All kidding aside, I will not be touching anything. Again my whole reason for asking in the first place was to see what options were available so I can push my friend in the right direction. All I think about is him cheaping out, and end up powering the utility lines while a linesman is attempting to fix because he forgot to hit the main switch on the pole.... Or if damage could happen when the power comes back one while his generator is running (again if he forgot to flip the switch). Only reason for asking was informational. Mama raised a fat kid, not a dumb one

I do appreciate the info from both of you. I think that will pretty much take care of it. I'll relay the information and hope it works out Thanks guys!

 

[nehog]

First, I'm an EE, who had done power systems at the industrial level. To give you an idea of the things I will do (for myself!) I have designed and built a three phase transfer switch system that feeds my house (single phase) while keeping the phases relatively balanced.

I considered what you are proposing with my setup. I gave it a *LOT* of thought, and in the end I decided that as much as I'd love to do it that way, it was not practical. You would need several control circuits to allow you to do the necessary switching, and some relatively expensive double throw contactors to switch the power.

You need a transfer switch at the pole where your main feed is, and feed the generator to that transfer switch directly. You don't need permanent wires (you could lay it down as needed, take it up when done), or you could bury the wires in conduit (just use the correct wire types.)

 

[mrb]

nehog, why the need for all these contactors and control circuitry to have a generator feeder from the shop to the house? Seems all thats needed is a pair of manual transfer switches.

I do believe the neutral has to be switched since the generator feeder comes from a different location and if you dont switch the neutral then you have a second neutral path from the house through the generator feeder, and back out the shop's feeder to the pole.

 

[rkevins]

The reason that transfer switches (here anyway ) are installed at or near the power pole where the main feed comes from is (or was at the time) by the power company. when a generator is running if the power is not disconected from the power company feed it will go back up the pole out the transformer to the main lines. when we installed the pto units the outdoor rated transfer switches were below the meter base, now with the diesel unit the indoor rated auto transfer/auto start control panel is installed per the maufacturer specks inside a building with the genset it would start, transfer and be running full power in seconds.
this is the type of manual I am talking about with the handel in the up position you are connected to the power co. ,in the center all is off, with it down you are connected to the genset. you will have power to everwhere with the genset just like you do from the power co.

 

[nehog]

nehog, why the need for all these contactors and control circuitry to have a generator feeder from the shop to the house? Seems all thats needed is a pair of manual transfer switches.

I do believe the neutral has to be switched since the generator feeder comes from a different location and if you dont switch the neutral then you have a second neutral path from the house through the generator feeder, and back out the shop's feeder to the pole.

You need a failsafe way to both connect the generator, and disconnect the utility power at the same time... As well, to be properly safe, you need to create an interlock so that should for some reason the utility cutoff contactor not operate, the generator one won't allow the generator to energize back through the utility lines. (A set of contacts on the utility cutoff contactor would suffice for this purpose, put them in series with the generator feed contactor. (The utility contactor, as I mentioned, needs to be a double throw type, which are not common.

 

[sdowney717]

nehog, how about a 4 pole switch on-off-on which energizes 2 separate contactors?
so when switch is one way and has power from source, its contactor is energized and vice versa. it is either one or the other not both can be energized simultaneously. Except they are not mechanically locked out.
Do contactors fail in the closed position? perhaps the control on-off-on switch could fail.

 

[mrb]

You need a failsafe way to both connect the generator, and disconnect the utility power at the same time... As well, to be properly safe, you need to create an interlock so that should for some reason the utility cutoff contactor not operate, the generator one won't allow the generator to energize back through the utility lines. (A set of contacts on the utility cutoff contactor would suffice for this purpose, put them in series with the generator feed contactor. (The utility contactor, as I mentioned, needs to be a double throw type, which are not common.

maybe I wasnt clear. Everything I was speaking to invloved running a seperate generator feeder from the shop to the house. So generator connects to shop panel through a manual transfer switch, and generator connects to a manual transfer switch in the house via this new generator feeder.

 

[nehog]

maybe I wasnt clear. Everything I was speaking to invloved running a seperate generator feeder from the shop to the house. ...

Ah, a classic apples/oranges! You're right, that is a solution as well, and would be reasonable to implement. I just totally missed your point of a separate feed to the house from the shop.

 

[mrb]

Ah, a classic apples/oranges! You're right, that is a solution as well, and would be reasonable to implement. I just totally missed your point of a separate feed to the house from the shop.

do you agree that the neutral would have to be switched in this arrangement?