Shop Power

I am starting to plan the power for my new shop which will be 65 feet away
from the house and across the driveway. The shop will run off the 200 Amp
service for the main house. The total cable length from the meter box to a
lug box in the shop will be approximately 120 feet. The first 45 feet will
run through the basement of the house. The rest of the run will be
underground in 2 inch plastic conduit. I plan to run from a 100 Amp breaker
with three 2-0 (00) wires (hot-neutral-hot) and a single #6 for safety
ground (green). I will probably drive a 10 foot ground rod at the shop too.
Note the neutral WILL NOT be connected to the shop ground rod. I found
several nice new, sealed 90' rolls of 2-0 at the reclamation yard for $25
each last year. Regulations in my area are such that I don't have to have
inspections. Does anyone see a problem?
Reply to
keith bowers
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In my town, they allow a house to have a 200+200 service. I kept the existing 200A panel and changed the power pole and meter base and used a 400A box. Then I pulled a 200A panel down to my shop. It's OK as long as there is an exterior shutoff switch the firemen can access.
Now I have enough power in my shop. I cannot imagine trying to live with less than 60 amps. Whatever you do, pull yourself a subpanel to your shop. And get a permit, else if you have a fire your insurance might not pay.
Grant Erwin Kirkland, Washington
keith bowers wrote:
Reply to
Grant Erwin
Haven't read the NEC lately, but IIRC there is only supposed to be one ground in a given system.
Something about circulating currents in the ground loop.
Or some such . . . Cheers, Fred McClellan the dash plumber at mindspring dot com
Reply to
Fred McClellan
I am not an electrician but have done a bunch of wiring as recently as half of today. I see no problem with your plans other then I think you could bump your amperage up to at least 125 amps and that might be nice if you intend to put in a "real" welder. Leigh@MarMachine
Reply to
Leigh Knudson
Why not connect the neutral to the shop ground rod?
Just wondering what the reason was...
Justin
Reply to
Justin
Why not connect the neutral to the shop ground rod?
Just wondering what the reason was...
The NEC requires the neutral to be grounded only at the service entrance panelboard.
Reply to
Peter H.
Ahh I see...
Humm doesn't make much sence but that's the code then you go with it....
Thanks,
Justin
Reply to
Justin
Ahh I see...
Humm doesn't make much sence but that's the code then you go with it....
This avoids "ground loops", and that is important.
Reply to
Peter H.
safety
My shop is in the basement, so it is a little easier. However, here are some things I did which you might consider:
1. Must have a sub-panel with its own main breaker for the shop. That is, a 100 amp breakers in the house to another pair of 100 amp breakers in the sub-panel. That way, you have emergency shut-off from either place and far more convenience in rewiring -- see below. 2. Make the sub-panel big. I put in a twenty-breaker sub-panel. Now each machine has its own, dedicated line. No sharing of lights and outlets, etc. It is really nice to not have to worry about overload.
3. Two circuits (110 volts) from the house, directly, without going through the sub-panel. One #12 for power, the other #14 for lights. That way, when you put in a new circuit, you shut the house side breakers, you have a totally dead panel in the shop and you still have lights and power with which to work.
Boris
Reply to
Boris Beizer
Good points, thank you. I found four 90' rolls of nice new 00 wire at the scrap yard for $25 each last year. This gives me the optino of upping the current later if needed. I will probably do 8" #2 stubs from the breaker to the 00 hots using half nuts for the connections. If I need additional power later I can add a second 200 Amp feed. Local electricians tell me the power company doesn't encourage second meters; don't know why. As for welding that will be from a tractor-mounted 28 Volt 300 Amp DC generator. Another conduit will have the emergency generator feed from shop to house, so I will have a way to light things up while working on the main feeds plus fiber optics. Aonther will have water and air and phone lines. A fourth will have coax, CAT-5e, and other control cables.
Reply to
keith bowers
Thanks for the URL; the block look like just what the doctor ordered. I'll drop the second ground rod idea unless local code requires it.
Reply to
keith bowers
In this case it appears that he is connecting the grounding conductor to the ground rod in the shop, just not bonding it to the neutral. One of the reasons for this requirement is so that the grounding electrode conductor does not function as a parallel neutral return or even worse as the main neutral in case of a lost neutral. This is particularly bad if metallic conduit is serving as the grounding conductor, because the connections will get mighty hot with sustained amperage going through them.
WRT to the ground rod controversy, it is very complicated and some of it is beyond me, but I have seen problems with elevated neutrals connected to copper plumbing systems serving outdoor spigots. People who used the spigots while standing on the wet ground with bare feet were getting mild shocks. There was a small but significant potential difference between ground rods connected to utility pole neutrals or the service neutral and any driven ground rod 10' away, which varied continuously and I suspect was related to voltage drop on the neutral of the somewhat inadequate utility distribution system. In this case the people were "earthed" with their feet, and at a lower potential than the service entrance neutral or the copper plumbing bonded to it.
Reply to
ATP
Speaking of ground rods - I had a 'little' incident with a tree that resulted in the severing of the neutral feed (1440 volts) to my house or at least the transformer to my house (and a couple more) - don't ask! The tree brushed the hot wire on the way down and popped the breaker at the sub station. That breaker was programmed to try and re-connect and re-connect it did. Much to my suprise the house was up and powered as if nothing had happened. ALL the ground return from the transformer and the house (and the neighborhood) was returning through *the ground*. Although everything was working normally I knew I had to 'fess up' and face the music. The 'music' in this case meant bringing in a crew by helicoptor (no roads in this area - an island to boot). Think $1000.00/hr for the chopper alone. There is no hiding from the wrath of the power company (BC Hydro) in this situation. My honesty actually saved my ass. Owning up earned me a place in history as no one had ever done that before. The local manager allowed as "folks always tried to plead innocent - but, in the end we *always* caught them". In my case I realized that the pattern of fallen trees pointing away from a newly installed Satsllite dish might just prove embarassing. The power corp buried the minor fix in a bogus meter mixup and it cost me not a single dime - and no - I wouldn't get off that easily if I screwed up again.
Regards Ken (boning up on his trig in case I have to calculate the arc described by another falling tree in the vicinity of power lines,)
distribution
Reply to
Ken Davey
Speaking of ground rods - I had a 'little' incident with a tree that resulted in the severing of the neutral feed (1440 volts) to my house or at least the transformer to my house (and a couple more) - don't ask! The tree brushed the hot wire on the way down and popped the breaker at the sub station. That breaker was programmed to try and re-connect and re-connect it did. Much to my suprise the house was up and powered as if nothing had happened. ALL the ground return from the transformer and the house (and the neighborhood) was returning through *the ground*. Although everything was working normally I knew I had to 'fess up' and face the music. The 'music' in this case meant bringing in a crew by helicoptor (no roads in this area - an island to boot). Think $1000.00/hr for the chopper alone. There is no hiding from the wrath of the power company (BC Hydro) in this situation. My honesty actually saved my ass. Owning up earned me a place in history as no one had ever done that before. The local manager allowed as "folks always tried to plead innocent - but, in the end we *always* caught them". In my case I realized that the pattern of fallen trees pointing away from a newly installed Satsllite dish might just prove embarassing. The power corp buried the minor fix in a bogus meter mixup and it cost me not a single dime - and no - I wouldn't get off that easily if I screwed up again.
Regards Ken (boning up on his trig in case I have to calculate the arc described by another falling tree in the vicinity of power lines,)
distribution
Reply to
Ken Davey
That happens here from time to time - some times we are cutting them - we being neighbors.
Sometimes it is a stick of TNT a group member plants, or a car/truck crunch.
Often it is a Fir - whose roots have rotted in the soggy soil.
The last time was a 36" Fir that fell across the road and across my property. The scars a tree that big are massive. It brings everything down with itself.
It took several days for he county to decide it was in fact their tree and to send a team out.
It is fantastic what some of this stuff weighs! - Had a Redwood tree fall across a friends truck on Hwy. 17 (55 MPH) and crush the engine block into the pavement.
Oh it stopped the truck instantly. My friend, was in a good safety belt - just got bruised big time. Got a new truck.
Martin
Reply to
Eastburn
Hwy. 17 to Santa Cruz?
michael
Reply to
michael
Now you are setting your self up for some lovely ground loops.
Also, you will want (and need) a transfer switch for your generator. If you can iso late the neutral at the generator, and use the service entrance ground to ground it, you only need a 3 pole. If you can not isolate it at the generator, you need a 4 pole switch.
Reply to
jk
> keith bowers wrote: > > >>Good points, thank you. >>I found four 90' rolls of nice new 00 wire at the scrap yard for $25 each >>last year. This gives me the optino of upping the current later if needed. >>I will probably do 8" #2 stubs from the breaker to the 00 hots using half >>nuts for the connections. If I need additional power later I can add a >>second 200 Amp feed. Local electricians tell me the power company doesn't >>encourage second meters; don't know why. As for welding that will be from >>a tractor-mounted 28 Volt 300 Amp DC generator. Another conduit will have >>the emergency generator feed from shop to house, so I will have a way to >>light things up while working on the main feeds plus fiber optics. Aonther >>will have water and air and phone lines. A fourth will have coax, CAT-5e, >>and other control cables. > > Now you are setting your self up for some lovely ground loops. > > Also, you will want (and need) a transfer switch for your generator. > If you can iso late the neutral at the generator, and use the service > entrance ground to ground it, you only need a 3 pole. If you can not > isolate it at the generator, you need a 4 pole switch. > > > > >
Reply to
keith bowers
That is where the Highway ends or starts depending on the train of thought!
Yep, Martin [ in the mountains on the Pacific Plate, work in the North American Plate ].
Reply to
Eastburn
It'll always be 17 to me. When I was a kid we went and walked on it before it was open all the way to Camden Ave.
Had a house at Love Creek until it rained once. Still had it after, S C County took the bureaucratic way out of that.
michael
Reply to
michael

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