Shop wiring...need some quick answers

[91FE]

Alright, I know this has been covered to death, but it seems everyone's situation is a little different (I searched...I swear).

I'd really like to power up my new shop and I figured now would be a decent time to buy most of the parts since I have one of those HD 10% off coupons.

The specifics:
Small 12'X12' detached "shed"
The feeder run will be something like 90' long

I figured on the following circuits:
(1) 15-20A lighting
(2) 20A general power (BT, CMS, DP and misc stuff)
(1) 20A Dedicated DC/Compressor
(1) Maybe future A/C - not sure, haven't worked in there yet

The Questions:

1. I've read the debates on 50-60A sub-panels vs. 100A. The argument is...the higher rating doesn't cost much more. BUT...do I really need 100A? The feeder is going to cost more, the conduit will be bigger and the wire will be harder to work with.

2. I'm confused with how many wires I need to feed the panel with. I read both 3 and 4... the difference being 2 hots. What gives?

3. What gauge feeder wires do I need for 60A? How about 100A?

4. The tricky question: My yard drops pretty good on the side, so-much-so I have a walk-out basement. I want the feeder conduit to come out of the side of my garage (where the panel is), go underground to the corner of my house, and come back out of the ground as the grade drops away. I then want that exposed conduit to run along the side of my house (pretty much even with the first floor), under the deck and into the shed (which is under the deck). Is it legal to have a conduit with a 50-100A load within hand's reach?

Thanks for reading...and commenting.
Scott

[JBCrooks]

1: You don't really NEED 100A with the setup you described, but its always better, IMO, to go with more than what you need. Cost wise, the 100A may be about the same as 60A these days since copper has gone up so much. (the 100A triplex you can get in aluminum)

2: You will need 4. 2-hot 1-neutral 1-ground. The first panel off the meter base can have a combined neutral and ground, but all sub-panels must have a seperate neutral and ground. So you run the 4 wires, but 2 of them hook up in the same spot in your first panel. Don't try to make sense of it...its government.

3: As a general rule of thumb, 20A - 12g 30A - 10g 40A - 8g 60A - 6g.
For the 100A, you would be best looking at #4 aluminum triplex and a grounding wire....most likely a 6g aluminum.

4: It's not wrong to have the wire within reach so long as it is in conduit properly. If you have an underground service on your meter base, you basically have an unprotected #2 size wire in conduit coming from the ground up to the meter.

[Anna]

Hi, there. Newbie perspective here. Probably not very helpful, but I just got my shed wired a few weeks ago. My shed is similar to yours. I had a 220 V/30 amp line in the garage. Shed is on the other side of the house. I had an electrician do the wiring, and this is what we did:

We snaked the line under the house, into a conduit and up into the shed. Inside the shed, I have 4 lines, each one is 20 amps. I know that totals 80 amps, which is more than the 60 amps that's available from the main, but I figured I won't be using all 60 amps at the same time anyway.

One circuit is dedicated to lighting and the AC. The AC I got draws only 4 or 5 amps. Lighting draw is practically nothing (8 x 4-foot fluorescent tubes). I'm going to hook up my air cleaner to the same circuit, and I don't expect any problems there at all.

Since the shed is pretty small, I had three walls wired with separate circuits. So I know that if I have something plugged in one wall, the other two walls are free. It's just easier for me to keep track of which circuit has a load. Most of my tools are 15 amps, hence the 20-amp circuits. The lighting circuit is not used for any of the tools at all. Well, I did use it for the power planer (because I got too lazy), and the lights did not hiccup at all.

Inside the shed, we used #10 Romex to handle the 20-amp lines. For the 60-amp line from the garage to the house, we used #6. I think that was about 60 feet in length. I've seen some guidelines about length versus grade of wire for certain amperages, but I'm just too lazy to search it online right now (well, it's really warm around here lately).

The only reason I went with 60 amps is because that's what was available and most convenient. I'm a little unsure about the need for 100 amps, but then I'm new to all this, so my point of view is a bit limited. And it's not like you'll be running 3 or more tools at the same time.

Unless you decide to put in a 220 V outlet, in case you one day decide to buy those really big tools like the Unisaws, or whatever they are. But then again, in a 12x12 shed, I doubt you'll have the space.

[crokett]

I can't answer specifics on wire sizes, etc but I can say this: From experience install the 100A service unless cost is prohibitive to do so. I've never heard of anyone (and certainly not me) wishing they had less power. Everyone wants more.

Besides you might want to add lights or outside outlets or something later on.

[gsmittle]

I'm planning on 100 amps to my new shop (pics coming soon). After all, you need enough power to keep the fridge and plasma TV running... Not to mention the tools.

Actually, eventually I'll be installing a fairly hefty DC and maybe someday a big-boy saw. I inherited a huge air compressor from my father which requires 220 right away (or 221, whatever it takes ).

Hoping to get estimates from the electrician in a couple of days.

g.

[91FE]

Thanks for all the advice.

I had hoping to buy the parts before going away this past weekend... it just didn't happen. I'm still on the fence about the panel size. I'm pretty sure I'll never come close to growing into a 100A panel. I'm only using one 15A duplex in the garage currently... and the new shop is only 12' X 12'. Not really enough room for much growing.

[scorrpio]

2: You will need 4. 2-hot 1-neutral 1-ground. The first panel off the meter base can have a combined neutral and ground, but all sub-panels must have a seperate neutral and ground. So you run the 4 wires, but 2 of them hook up in the same spot in your first panel. Don't try to make sense of it...its government.

Actually, electrical codes are there for a very good reason, just like all other codes.
Here is a quote:
The most fundamental requirement in controlling stray voltage is to rigorously maintain the distinction between Ground and Neutral (the grounded conductor). The Neutral wire is a conductor that provides the return path from the load back to the power source. The neutral has White insulation and is grounded only once at the service entrance. The neutral wire is a conductor and must never be grounded at a second place in the system. If it is grounded a second time, part of the neutral current will flow through the building structure and will cause stray voltage.