small workshop wiring

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  #1  
Old 03-09-07, 11:40 AM
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small workshop wiring

Hi,I am in the process of wiring a small work shop, believe it or not it has run
on an extention cord from house for three years!.I have 4 110 recepticles,
5 flourecent shop lights,and a 2hp 14amp compressor 100 max psi. I plan to
feed from main box at house with 14/2 with ground, sub box with two breakers,both 20 amp,one will be dedicated to compressor only,the other to light's/recepticles..my questestion's : will the 14 gauge carry the load,and
what size breaker should I use at main(at house) would 20 amp be enough
or should I go higher since I have the two 20amps at sub panel? it is only
a hobby shop and no two electrical tools will be used at same time..the
compressor I mentioned(new) gas been kicking breaker since I bought it
(last week) and kicks breaker when it cycles...thank's
 
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  #2  
Old 03-09-07, 12:20 PM
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No, #14 is not enough (not by a long shot). And even so, you need xx/3, not xx/2.

But first things first. Is this workshop attached or detached? And how far away from your main panel is it?
 
  #3  
Old 03-09-07, 12:22 PM
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You are way off base on many points.

First, saying that the workshop has run on an extension cord for three years is nothing to be proud of.

Feeding with 14/2 would be stupid. Protecting this 14/2 with a 20 amp breaker at the house would be asking for a fire. 14 gage wire is a maximum of 15 amps. Period.

You are, at least now, in way over your head.

If you want a sub panel at the workshop, then run the proper wiring for one. This would be at least 30 amps at 240 volts. Then, the sub panel at the workshop can have two 20 amp breakers if you wish, and you will still have room for more. However, I would add more. I would separate out the receptacles from the lights. Put the lights on a 15 amp breaker, and run two circuits at 20 amps for the receptacles.

This workshop sub panel, if in a separate building from the main panel, will need a ground rod and should be run with four conductor cable or four conductors in conduit. Four would be required if the sub panel is in the same building.

Another (cheaper) and less power alternative which would work would be to run a multi-wore circuit to the garage. This could be a 20 amp multi-wire circuit, which would give you two 20 amp circuits at the garage. I donít recommend this, because it has no room for expansion.

As I said, you are in over your head. Electricity can and does kill people and start fires. Please buy and read at least three books on home wiring BEFORE you go any further with this project.
 
  #4  
Old 03-09-07, 12:31 PM
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waterbird, Bob and I are going to play good-cop/bad-cop here. Bob's job, as bad cop, is to scare you enough to make you prepare well--there are very real dangers here. My job, as good cop, is to encourage you that you will be able to do this successfully after that preparation. But please don't start this project until you are well prepared (i.e., don't set aside time this weekend to do it--there's no way you can learn all you need to know that fast).
 
  #5  
Old 03-09-07, 01:05 PM
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Honestly, you haven't given enough information to do a load calculation. Saying 110V really isn't helpful, other than you aren't currently running big tools.

But there are people here to help, so list out the big tools you'd like to run and anything that would use electricity to heat, as those are the big draw items. What size is this workshop? Would you ever run a/c? Another very important question, how far is this workshop from the panel. There will be voltage drop over 100ft.

Your plan to run 15amp circuits is a good start, but isn't practical. I would at least run a 30amp panel, preferably 60amp. It would be a pain in the a** to be out in the workshop in the dark b/c you blew your circuits running a saw.
 
  #6  
Old 03-09-07, 01:38 PM
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well thank's for the heat,I did'nt say I was Proud of the ext. cord,it was
simply a fact..not the smartest one by far,but since our home was destroyed
by a hurricane a few years back(Ivan) and the shop was the only thing that
was salvaged,built my my own two hand's,every nail,every screw,that was
run for over 12 years with buried unsheathed 14/2 and no sub panel hooked to a 25 amp breaker at main,never dimmed a light,never blew a breaker in all
those years...the original wiring to shop was destroyed by the heavy equipt.
that was tearing down our house..while my shop watched,after weathering
a cat 3 hurricane.now that I'm proud of! Saftey is paramount with me,but
there is a thing called overkill...a 12X12 shop with the few light's I have,and
I,being the only one to use this space,I did'nt want to over complicate thing's
but I now after reading how stupid I am,will run 10 gauge wire with a 40 amp
at main on 240v with the two 20 amp dedicated breaker's..am I getting
closer? thank's
 
  #7  
Old 03-09-07, 01:44 PM
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Getting closer. Are you planning on using "romex"?

I think 40amp would be too much for a non-connected building (there is a NEC table that permits higher breakers for subs inside the home), so I'd go with 30amp.

Also, you want UF or THWN in conduit.
 
  #8  
Old 03-09-07, 01:48 PM
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Closer, but not there yet. 10 gage wire can only be run at 30 amps max. However, that's 30 amps at 240 volts, so you could feed two 120 volt 20 amp circuits with that, and run them at 20 amps.

Please don't think I was calling you stupid. Many intelligent people do things that are far worse than using an extension cord for a shop. Unfortunately an unsafe setup will work just fine for a while., sometimes forever. However, as often is the case, an unsafe situation sometimes kills someone or causes a fire.

My intention for the harsh language is to impart a healthy respect for electricity. I am not attempting to make you or anyone else afraid of doing work yourself, I just want to make sure that you do so safely.

One of the reasons for inspections is that an inspector will, hopefully, catch the mistakes made and force them to be corrected. I strongly encourage you to buy and read books, as I have indicated, and then come up with a plan. I then encourage you to run the plan by the electrical inspector for your area and/or us here. Then, and only when we all agree it's safe and proper, do I recommend that you proceed.
 
  #9  
Old 03-09-07, 03:13 PM
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What seems like overkill now, may in fact be considered sub par in the future. Choose your path wisely.
 
  #10  
Old 03-09-07, 03:36 PM
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fair enough,great advise from all.....my thank's
 
  #11  
Old 03-10-07, 06:28 PM
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Safety First!!!!!!

Bob (racraft) cant say enough about the healthy respect for electricty and the need for utmost safety when working around it or installing electrical equipment and wiring. The codes that all of us electricians follow everyday are there to keep us all safe, please respect them. You dont have to be scared of electricity but you had better RESPECT it. This stuff can kill you, and remember, its not the voltage that kills you it's the amount of amps(amperage) so even a 120 volt circuit can be deadly under the proper conditions.
Please play safe!!!
 
  #12  
Old 03-10-07, 10:41 PM
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Originally Posted by waterbird View Post
....that was
run for over 12 years with buried unsheathed 14/2 and no sub panel hooked to a 25 amp breaker at main,never dimmed a light,never blew a breaker in all
those years...
I'm not surprised at all that you never tripped a breaker with 14 gauge connected to a 25 amp breaker, the wire would more likely burn up first, and the fact it hasn't is what surprises me. You could've burned the house down but looks like the hurricane saved you from that.
 
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