Power to detached shop

[Matt Meiser]

It sounds like you've already looked into it and you could do it, but in a recent discussion on our club's forum about our local utility, they won't do separate service to an outbuilding on the same property anymore. The outbuilding would have to have a separate address.

I disagree on the 100A service. If you are running a 3hp cyclone, a 3hp Unisaw, lighting etc and/or add the startup load of a central AC unit or a large air compressor you are getting up there on load. Have a friend over working with you and you could go even higher. I'd consider 100 to be the minimum for anything bigger than an average 2 car garage. You might not need it now but if you decide you do later you have to spend the money all over again.

[Tom Ewell]

I thought about adding new service, but the pole is pretty far away and the power company will not add another service for free. Could I run a service entry cable inside the house (thus no conduit) and then a junction and switch to individual conductors for the underground run?

Nick, my shop garage combo was new construction. Permits, inspections etc. were all in play. My electrician (who did my house) already knew that additional load from my existing service was insufficient to feed the shop so the point was mute.

My house service was actually further away from the shop than the utility pole so any trenching and other costs associated with it worked out to be actually cheaper.

Loads calculated should be all potentials, the "well I'm not going to use machine A at the same time as machine B so I don't need X amount of current" argument can be of some merit but if both machines are wired or plugged in then the service should really be capable of handling both.

In my case I know already that I'm in good shape, when I get around to replacing my smallish compressor with a big boy, all I need to do is run a new heavy circuit from the panel and I'm covered,don't need to worry about what happens if the compressor kicks in while I'm in the middle of ripping some good stuff on the table saw.

A smaller sub service may/should be just fine for your purposes just do it with safety first in mind.

We're all adaptable, we can figure out how far we can load the wire before tripping the breaker, that's part of the fun, just hope we don't overheat stuff enough to cause a potential breakdown that costs a lot more than the intitial investment.

[Stan Krupowies]

Bob, just a friendly note that the space bar is your friend. It really helps to make things more readable.

[Kevin W Johnson]

Bob, just a friendly note that the space bar is your friend. It really helps to make things more readable.

I'm guessing that he uses it already, but maybe it doesn't always register the hit. At best he may just need a new keyboard.

[Todd Burch]

I'm guessing that he uses it already, but maybe it doesn't always register the hit. At best he may just need a new keyboard.

I'm guessing it was due to a copy/paste operation from some other previous use of the explanation.

[Mike Heidrick]

I just got a bid from Ameran for dedicated 200a service to my shop. $1915.75 just for their bill. The engineer said it was considered commercial since it was second service on the property.

I am 186' from my existing service meter on my house. I am now considering 320amp service to that meter and a seperate new trenched line to the shop - a 200amp panel there.

Right now my shop is the third panel - it connects to the attached garage panel and that to the main panel.

I want to run a 20-30hp phase converter eventually so that is my driver for 200amp to the shop.

I found 200' of service entrance 4/0-4/0-4/0 aluminum on ebay for about $550 - momouth triplex URD. It says used to feed a panel - that could be used from a breaker at the meter to the shop (buried outside in conduit and ran to a new shop panel) correct for 200A service?

I am in the county and do not have to have permits/code for electrical work on my existing property here but I would like to have it sized correctly.

[Nick Cook]

Thanks for all the advice guys. As I'm adding up all the costs to run from my main panel, I think I'm going to try to get a firm quote for new service. I'm not close to a pole and but at the end of the day it may be cheaper or at least the same price, with the added advantage of me not having to do all the work.

Ill keep everyone posted on what I come up with.

-Nick

[Richard Jones]

".......He stated SER cable cannot be used in conduit underground, so I used four individual THHNwires in the underground conduit....."

Pretty sure you can't use THHN in underground conduit. You sure it wasn't THHW?

[Gary Max]

I contacted the city engineer who came out and did a inspection-----showed him what I wanted to run (amps I needed). They upgraded my can and I hung a second meter. I worked with the building inspector making sure his wants where meet. He wanted a GFI next to the door--- I didn't ask why. The trick is pleasing the folks that run the show and get what you want at the same time. Don't look for short cuts they will haunt you later in the game.

[Bob Deroeck]

Richard queried "".......He stated SER cable cannot be used in conduit underground, so I used four individual THHNwires in the underground conduit....."

Pretty sure you can't use THHN in underground conduit. You sure it wasn't THHW?

Richard is correct. The wire I used was dual rated for both THHN and THHW.


Bob

[Carl Beckett]

A smaller sub service may/should be just fine for your purposes just do it with safety first in mind.

We're all adaptable, we can figure out how far we can load the wire before tripping the breaker, that's part of the fun, just hope we don't overheat stuff enough to cause a potential breakdown that costs a lot more than the intitial investment.

This is a good question and that is: Should we apply a safety margin on top of the margin that is built into the electrical codes?

Im an engineer and by nature like to overbuild stuff. A neighbor does electrical liability claims as a consultant - his view is that the codes are designed to allow for a safety already. If its overloaded then thats what a circuit breaker is for. So as long as wires, outlets, connector boxes, etc are all sized properly then the system is working and is safe. He asked me how many times I have ever tripped my breakers and I admitted - never (thus, I dont know if I have 10% overcapacity or 50% overcapacity)

Philosophical, but I know I do overdesign and sometimes the cost is significant to me.

[Tom Ewell]

Carl, I worked out of my basement for a while using a few dedicated circuits and knew the limits for each circuit before the breakers would trip and adjusted my work flow accordingly. So using an a smaller service can be done but it is a pain and does not allow much in the way for expansion.

As you say, a safety factor is built in for the circuits per code, no problems there. How much to consider over and above code is hard to figure, I can see using 12awg for all standard circuits be they 15 or 20amp, maybe bumping things up for dedicated circuits if the upper limit is close but much beyond that might be superfluous for a shop assuming of course that the service itself is adequately spec'd for load.


My point about safety first is the potential consideration by some to do an easy fix like strapping in a 20amp breaker to feed a 15amp circuit, I've seen it done.