Thinking Of A Way To Hook Up My Generator

[clearance]

Broken powerlines are to be grounded to the neutral before work commences, always. That means on both sides of the break, right to the neutral. Always. Do not buck trees off the line, do not go near the line, keep everyone away (at least 33' for a distribution line).

And it is a fact that generators are to be installed to house, shop, or barn wiring by an electrician. With a backfeed preventor.

 

[046]

hey wirenut... what gen-set panel would you recommend for a residence with 3 phase power with a wild leg?

currently running a single phase 200 amp breaker panel for main house, then a separate panel with 60 amp fuse on each leg for 3 phase A/C compressor/heating system.

naturally both systems are run in parallel from same feeder lines. with main house panel using only two legs. the wild leg is not used for main panel.

I install prolly 1 Gen-Set panel every six to eight weeks, then tested and inspected. Just hate to see burnt home elctronics and appliances over a simple fix.

 

[wigglesworth]

STOP do not do it. Hire a Professional. Not worth the risk. I am a licensed electrician. I have installed back up generators on homes. In the same way the "pro" guys try to talk a "newbie" out of felling some huge oak over there neighbors house, i am also telling you, NOT WORTH THE RISK!!! Hire a pro. Could get some people hurt or killed.

 

[Wirenut2266]

046: Are you sure you have 3-phase? Is your residence now and old farm sight or some other commercial building converted. I'll assume you know what your talking about, not too many folks know about the "wild" leg. If you have a true wild legg off an old tub from utility, the "wild" leg will be around 195 volts to ground or neutral. As far as generator panel, you can use the same as everyone may use, it's this wild leg just makes me really think about your setup. Oh-crap......Wait.....Wait......What is phase to phase reading with a digital meter on your home panel, 208 or 240? Now you got my gears really turning. Now i'm wondering if you CAN do it or not? Tell me voltage, remember, your Gen-Set will put out 120/240. Unless........You really do want a true 3-phase 120/208 generator, ah-dude, that would be sweet. Remember, you can buy a nice 3-phase gas welder/generator and you will get the best of both worlds!

Seriously though, your setup sounds complex, be very careful and get multiple opinions for safety reasons, best bet, hire it out.

 

[Labman]

Lab: I still think your missing my point. Let's assume your home has this interlock you showed in a post. Did you install this and test, or a electrical contractor? Was it inspected by local authority having jurisdiction? Be honest now? I'm saying your setup is a safe one. but will be hell on your Gen_set and home electronics and appliances. Your Gen. has no way enough power when everything in home when it needs it. I install prolly 1 Gen-Set panel every six to eight weeks, then tested and inspected. Just hate to see burnt home elctronics and appliances over a simple fix.

The authorities are pretty lax here. Yes I installed it my self. Tested? I have tried to turn both breakers on with the plate in in different positions. You can't do it just as the approved device is susposed to work. You need to accept that somebody has designed a good product, gotten it approved and is making it easier to do the job right. I have also checked the voltage when we were using a bunch of stuff and it is about the same 118 volts as under a light load. I have 10-3 with ground between the generator and the 30 amp breaker it feeds.

By the way, I know they are shabby outfits, but Square D and on their Gold Prime panels, GE are selling the same thing, and I think a lot cheaper.

Now why don't you forget about it and get on the guys that are skipping any backfeed preventer?

 

[046]

yup... I'm sure there's 3 phase to my house.. it's one of the few in Tulsa with 3 phase... reason was to drive the fairly large semi-hermetic compressors in this area that was built in the 50's.

mine is one of the few water tower units still functioning... I re-engineered a modern copeland semi-hermetic compressor from the aging radial piston compressor.

not a licensed electrician, but have often thought of getting licensed.

have been around electrical equipment for quite sometime. fully equipped with all the safety gear. Used to be in the Electrical Supply business a few years back.

yes my gear is Fluke and Klien and I do wear double insulated gloves that I keep in it's own protective bag. my ladders are insulated fiberglass. etc..etc.

there's two completely separate circuits ran in parallel... two legs drive the main panel to house (wild leg is not used or it'd blow up most devices) then a separate fuseable panel is used for the AC/heater system. 60 amps on each leg... have to be careful of proper rotation direction anytime 3 phase wiring is touched.

just took reading at 3 phase panel with fuse block removed. reading were: 206.3 phase to phase... 174.5 wild leg to ground.

taken with Fluke 87 true RMS meter

046: Are you sure you have 3-phase? Is your residence now and old farm sight or some other commercial building converted. I'll assume you know what your talking about, not too many folks know about the "wild" leg. If you have a true wild legg off an old tub from utility, the "wild" leg will be around 195 volts to ground or neutral. As far as generator panel, prolly a full blown transfer switch is needed, I never seen or at least looked into a 3-phase on a small scale as you may want? I have made quite a few up from parts which is legal, just don't know if they make a factory interlock for small frame 3-phase breakers? I bet not. You may need to dig deep in pockets, sorry. Humor me, do you have just a large 3-phase panel in home, or another building with a switchgear, then that feeds home panel. Watch that wild leg, you hook up a 120v. branch circuit to it, you'll cook some stuff? If you put an electrical meter from phase to phase, does your meter say 240v. or 208v. Now I'm just curious? Be safe!!!

 

[treeslayer]

.and at least one he let me slide with (sneaked one 110 feed though the 2AWG feed conduit...not allowed & I knew it)...up to code.

sure its legal, if the wire insulation matches (600vac). fill capacity is rated to the conduit size, not wire size. adding a couple of #12's is allowed.

 

[Labman]

Chances are your generator only puts out single phase. So you are out the air compressor when the power is off. Just put some sort of a backfeed preventer on your single phase panel and connect the generator to it.

 

[cord arrow]

I'll take your word for it tree...couldn't have been too bad...he passed it.

I would have liked to run more in there...but guys on the electrical sites said taboo...

 

[treeslayer]

Chances are your generator only puts out single phase. So you are out the air compressor when the power is off. Just put some sort of a backfeed preventer on your single phase panel and connect the generator to it.

almost all generators make 240vac, single phase. this will power most air compressors, as they are also 240 vac single phase.
having ENOUGH amperage though, is the question, especially if trying to run anything else.
I'm not trying to nitpick, but a backfeed preventer? there are backflow preventers`in the plumbing/pipefitting field, but sorry, this is improper nomenclature. As a rough description, I get it, but as a master electrician, I'm gonna tell ya; you need a double pole, double throw transfer switch.

http://www.smps.us/transferswitch.html

a lot of spirited debate, and good advice here in this thread. but the bottom line is, there are a lot of shortcuts, and all are meant to save money, not save lives.

cord arrow, if you have your inspection,
and a few more wires wander thru?..............................
its only a problem if you have a fire in the panel area, and the fire marshals or insurance investigators find out. IT IS a fire hazard, too many current carrying conductors are a risk.

a slight risk, though. get it?

 

[046]

thanks for the clarification... for 3 phase I'd need a triple pole, double throw switch. instead of the double pole, double throw shown below.

even though my genset is only putting out single phase 220 and system is only using wild leg for the compressor... I'd want a third pole just to make sure wild leg totally isolated when tripped.

this is getting to be quite the production... may just keep using a beefy extension cord!
especially since our neighborhood should be going to underground wiring within 1-2 years.

 

[treeslayer]

yup... I'm sure there's 3 phase to my house.. it's one of the few in Tulsa with 3 phase... reason was to drive the fairly large semi-hermetic compressors in this area that was built in the 50's.
there's two completely separate circuits ran in parallel... two legs drive the main panel to house (wild leg is not used or it'd blow up most devices) then a separate fuseable panel is used for the AC/heater system. 60 amps on each leg... have to be careful of proper rotation direction anytime 3 phase wiring is touched.
206.3 phase to phase... 174.5 wild leg to ground.

"A high leg delta (also known as wild-leg or red-leg delta) is a type of electrical service connection sometimes found in older three-phase electric power installations.
This type of service is supplied by a transformer having four wires coming out of the secondary: the three phases, plus a neutral that is used to center-tap one of the windings. The voltages between the three phases are the same in magnitude, however the voltage magnitudes between a particular phase and the neutral vary. The phase-to-neutral voltage of two of the phases will be half of the phase-to-phase voltage. The remaining phase-to-neutral voltage will be √3 times half the phase-to-phase voltage. Typically, the transformer is connected such that the 'B' phase is the 'high' leg."

so you have the old delta 3 phase, all the new sets are derived from a wye configuration,
with equal voltages.
you can use standard 3 phase equipment, rated for 240vac, but it costs more. especially if you buy 600vac equipment, which is used for 480 volt applications. but surplus, or used ?
talk to some commercial electricians doing renovation work.

 

[treeslayer]

thanks for the clarification... for 3 phase I'd need a triple pole, double throw switch. instead of the double pole, double throw shown below
]

exactly. you are on like donkey kong, bro !!

 

[cord arrow]

I get it tree....

 

[Labman]

almost all generators make 240vac, single phase. this will power most air compressors, as they are also 240 vac single phase.
....

The OP specified he has a 3 phase. Yes, rare in a home

....I'm not trying to nitpick, but a backfeed preventer? ....

I never saw that phrase outside this thread, but it sounded to me like a good term for any one of the approved methods that isolate the generator and electrical line.

 

[treeslayer]

I never saw that phrase outside this thread, but it sounded to me like a good term for any one of the approved methods that isolate the generator and electrical line.

:agree2:

 

[projectsho89]

:agree2:

The plumbers already have dibs on that term....

Too late.

Steve

 

[treeslayer]

The plumbers already have dibs on that term....

Too late.

Steve

tried to tell em.......................da m plumbers

 

[beerman6]

Plumbers only need to know 2 things...

Payday is Friday and #### dont flow up hill...

JOKE!

 

[treeslayer]

ya wanna know the difference between an electrician and a plumber?




























an electrician puts his a$$ where a plumber puts his face.