Amps and electrical in shops


duckkisser

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I'm looking at buying a house and seting up my first shop. But to figure it out I was wondering how much amps do you run at one time? Will I be better off running a seperate line to the garage or would I be able to run a line from the box in the house to the garage and putting in a second box in the garage to run my machine off of. The house is currently running at 60 amp but I think I can put in 100 amp box in the house and the 100 amp cable will fit in the pipe in the roof. Then I can bypass the house box put in a second in garage off the same line.

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I highly recommend that you contact a licensed electrician in your area to determine if what you are plannning is allowed by local building codes. With a service for the house of only 60 amps, I think an independant feed for the shop is a good idea, but don't run the risk making your new home unsellable or unsafe by ignoring the codes!

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going to just want to get some basic ground information under me so i don't get taken advantage of and it would be nice to know what im doing before i do it.  and if i can figure out the best way to do this then i know what to ask for when the time comes to hook up the electricity.  

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In my garage shop I have 50 amps and it has never been a problem. I was in a similar situation as you when I put up my pole barn as my house panel was maxed out. In order for me to put a bigger panel in my house I would have had to run bigger cable from the transformer. I decided to run a separate line from the transformer to my shop.

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I dug a trench from the  house out to my shop running a wire from the house out to the box in the shop -  based on my electricians recommendation. He then wired the box in the shop for all my machines. If I had it to do all over again, I'd put in a separate meter for the shop to keep the electrical costs separate from the house since I operate a business out of my shop.

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decided to increase the pipe from the pole into the house large enough for 200 amp service but ill only put in 125 wires just like the option to increase it.  then ill put in a bigger box in the basement so that i have more space for the house.  as it is i have a circuit going out to the garage with like 15 amps for the garage door and light but im going to dig a trench and fill it with 2" pipe out to my garage and put a sub box out there.  ill have ether 125 or 100 in the garage depending on the size box my brother bought at an auction.  but ill need like 8 circuits to cover the garage and then have some extra for expansion in the future.  my goal is to roof my new house (ill probably be finished sometime in the afternoon tomoroow) and get electricity stretched out to the garage by winter/heavy fall rain (coming real fast)

 

i need to call com-ed (electrical) to find out the rules but is it ok to use pvc to pipe electrical into the home or do i have to use metal?  i know it depends on the city and state but what is legal in your area?

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It’s been awhile, so some of this might not be exactly right. I think NEC was updated in ’12 or ’13, but I haven’t taken a hard gander for some years. Things may have changed and my memory isn’t what it was… YMMV.

 

60a is the lowest allowed residential service under NEC. However, utilities [usually] run 200a service cable, so the header/mast may support the larger gauge service already – your electrician will check that. Actually, the last time I looked, the smallest header/mast available at the supply shop was 200a...

 

<but I think I can put in 100 amp box in the house and the 100 amp cable will fit in the pipe in the roof. Then I can bypass the house box put in a second in garage off the same line.>

 

Splitting a service is at the discretion of the utility. A local electrician will be able to guide you. You may be able to split the service as you indicated, or you may be required to up your current service and run a sub. A local pro is your friend…

 

Many shops run just fine with a 60a sub. However, the cost of going from 60a to 125a is basically the cost of copper and $40 for the larger panel/breaker/disconnect. You’ll never use the 125a (most never use more than 50a), but the extra ‘room’ is nice. In a shop, it's nice to dedicate branches and having the space in the larger panel gets you there...

 

Good Luck.

 

I guess after the Great Chicago Fire they got kinda strict on the building codes?
Or maybe it was a union thing?

 

We had a place in Lake Forrest -- it's the latter... definetly the latter...

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It’s been awhile, so some of this might not be exactly right. I think NEC was updated in ’12 or ’13, but I haven’t taken a hard gander for some years. Things may have changed and my memory isn’t what it was… YMMV.

 

60a is the lowest allowed residential service under NEC. However, utilities [usually] run 200a service cable, so the header/mast may support the larger gauge service already – your electrician will check that. Actually, the last time I looked, the smallest header/mast available at the supply shop was 200a...

 

<but I think I can put in 100 amp box in the house and the 100 amp cable will fit in the pipe in the roof. Then I can bypass the house box put in a second in garage off the same line.>

 

Splitting a service is at the discretion of the utility. A local electrician will be able to guide you. You may be able to split the service as you indicated, or you may be required to up your current service and run a sub. A local pro is your friend…

 

Many shops run just fine with a 60a sub. However, the cost of going from 60a to 125a is basically the cost of copper and $40 for the larger panel/breaker/disconnect. You’ll never use the 125a (most never use more than 50a), but the extra ‘room’ is nice. In a shop, it's nice to dedicate branches and having the space in the larger panel gets you there...

 

Good Luck.

 

I guess after the Great Chicago Fire they got kinda strict on the building codes?

Or maybe it was a union thing?

 

We had a place in Lake Forrest -- it's the latter... definetly the latter...

I ended up deciding to put in a 2" pipe to expand later if I want to. The electrician said I would have to upgrade the size of the pipe, meter box, wires, circuit box size everything from the roof to basement. Just figure I'll probably never need more the 100 amp but to be safe I'm placing 125 and heaven forbid I need more in the future but I have a pipe big enough for 200 amp. I then started puting in pipe in the ground from the house to run wire to the garage where I'll put another box to be my sub for the shop. Both the house box and the shop box will have more then enough circuits for expansion. My parents home growing up was always blowing circuits because there was not enough in each room. Rather not have that problem so I'm having more then I need right now but enough for when I have a family.

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I have a 200 amp main panel, I just got a quote to add a 100amp sub panel in my garage.  100amps is more than I need, but I will put a few machines on 220 and they hog up a lot of space in the panel.   In your situation, I think you will need to upgrade your main panel to 100amps and ask an electrician how big of a sub you can put in.   I was quoted $1400 for the full installation - running the line from my house to my attached garage, installing the 100amp sub, fixing a few problems in my main panel, and installing two 220v outlets and a bunch of 110s in my garage.   

 

Mike I'd be interested to hear how your install goes and maybe get the info on the electrician if it ends up being someone you'd recommend...I'm probably going to do the exact same thing at my house.

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  • 2 weeks later...

2" pipe size is good, just watch the gauge wire you are using.  You want to reduce voltage drop as much as you can.  Also no more than a total of 4 90 degree bends without a pull box.  As a matter of economy aluminum is used for feeders.  #2 Al is minimum for 100 amps and I would move up a size (#1) if over 100' per run.  Total amperage use gets weird.  In the past I wired a lot of 16 & 20 unit apartment buildings all with a 400 amp main.  Electric stoves and window shakers for A/C.  In theory each unit only could consume 20 amps, about a hair dryer and a couple of lamps.  Never had to replace a main fuse.  Bigger wire, yes bigger main, maybe not.

 

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On our house we has a 480 amp service but I have a commercial catering kitchen as well as a shop. I have 200 for the house and hundred for both the kitchen and the shop. I hear you about separate meters. I did get a unit that the electrician put in the kitchen sub box that shows how much current is flow through it.  But calculating based on it is a nightmare...

 

 

Chef

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Duck,

I'm sorry. I'm too late to this thread. All my good ideas have already been stated.

But just for reference. I have 100 Amps split from my house service to my shop. I have a new relatively home with geo-thermal. Where I live that means you get a 200 Amp box in your house. Probably over-kill to be honest. Where I live code says you get a main breaker in the house for the split line. Then you can choose if you want to have individual breakers in the house, in the shop or some combination there-of. I'd recommend putting them in the shop. Not so much for safety, but in the chance you do trip a breaker, you don't have to run back to the house to reset it.

 

Anyhow. One thing I like is that my shop has a breaker for each wall. So that way anything plugged in on my left is isolated from anything plugged in on my right. I have a dedicated 220 line for the dust collector. All the other 220 stuff (current or future) shares the other 220 line. As a 1-man shop its not likely I'd ever run more than one 220 machine at a time. For example it's unlikely that I can push a board through my table saw, my bandsaw and my jointer all at the same time.

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maybe if you try real hard you can run 3 saws at once.  

 

I will 99 percent of the time be the only one running a machine just was thinking that I might some day run a one on one one on two classes mostly turning in the garage.  I decided to just put in a 100 amp box in the house and run the electricity out to the garage and have a box out there as well. 

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My inspector would not let me have multiple machines on a single 220 breaker without a lockout key. I put the key into the outlet that I want to use and it energizes the machine. Still cheaper than multiple circuits. It is now attached to a big 2x4 cause of the times that I carried it to the house and left it on the bathroom counter. 

 

chef

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I know around my county you can only have 1 machine on a 220 breaker

 

I bought a circuit box with 20 spaces so I have plenty of circuits for the shop. 

 

I am going to need 6 circuits but if I ever move or expand I can put in more circuits in the garage. I bought this package because it was the better deal since it came with 5 circuits and a 2 pole circuit. so I ended up saving money buying a larger box.  ended up getting two one for garage and one for shop. 

1-lights

1-for dust collection

2-table saw

1-for left side of shop

1-right sides

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My inspector would not let me have multiple machines on a single 220 breaker without a lockout key. I put the key into the outlet that I want to use and it energizes the machine. Still cheaper than multiple circuits. It is now attached to a big 2x4 cause of the times that I carried it to the house and left it on the bathroom counter. 

 

chef

Even if you only run one machine at a time?

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No my brother owns the house( inherited it from his neighbor.) so I'm doing bunch of updates first then he will sell to me or rent to own. The lady who owned it passed away so I'm updating outside stuff like roof and electricity before it gets cold. After it get cold or rainy I'll start cleaning it out. Then I'll fix inside and move in. Since I'm doing the work on evenings and weekends it will take a while.

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