Detached workshop

[Bruce09]

I have been constructing a 12x20 backyard workshop. I am in upstate South Carolina and have reached the time to begin the electrical portion of my project. I have done a lot of research on the Web and looked at several diy wiring books. I was fairly confident until recently my girlfriend's parents lost there home to an apparent short or improper wiring. It was an older home but everyone is fine and thankfully insured. I've always respected electricity but now I'm second guessing my abilities, or rather cannot seem to find enough information to match my needs and circumstances. I'm confident I could pay close enough attention to the proper way to do it, it's just obtaining that info tailored to my specifics. I will briefly describe what I have going on and if someone is willing to help me out, keeping in mind that I've done very little electrical work in my 42 years. Before I get responses telling me to hire an electrician, you're probably right, but I enjoy doing things myself and don't cut corners or do enough to just get by when it comes to something this serious. Any advice or help you give will be appreciated. I'm not here to waste anyone's time, I just want to properly and safely do this myself.

I have a 200 amp main panel on a pole outside that feeds my home. The meter is on the same pole with one main breaker, a breaker for my heat pump, and one twenty amp breaker that is running 80' of 12/2 wire (copper) in pvc pipe underground to my old building I sold. I spliced into that with a drop cord and have been running a saw off of it. I'm sure this isn't safe, that's why I'm now trying to do it the correct way.

I ran up on 3 individual aluminum 6awg service wires, 80' long. I haven't buried them yet, not really sure they'll be enough for what I plan to run. Before the fire I had the mindset of, that'll work, now I want to make dang sure before I have to go back and redo or regret something. I want 8 receptacles, two switches, two four foot t-8 fluorescent lights, two bulbs per light. I am currently looking for a welder, I'm considering one of the Lincoln 230v ac/DC stick welders. I want to install a small window unit 120 ac and will have a radio, fan, and no more than one power tool running at a time. I don't have any large tools like 220 table saw or drill presses and won't get anything larger than a 120v tool except a welder. I'm sure there's more information I'll need to give I just can't think of anything else right now. The aluminum wire is thhn 94° 6 gauge. I want a subpanel breaker box inside my shop so I won't have to kill the power at the pole when it needs to be off. I'd like to save as much money as possible but do not want to just get by, if it takes $100 more now to keep everything safe later then so be it. I also don't want to go overboard and wire it for much more than I'll ever use. Thanks in advance.

 

[Reach4]

Figure 50 amp circuit for the welder? You may want to get figures on the model you are planning. Figure 12 amps for the 120 V AC AC. If you made that air conditioner 240 v, it would draw half as many amps for a given size.

Maybe 20 amps for everything else? So 60 amps would not be enough. 100 would give some extra margin for future growth. #6 aluminum would not be enough for even 60 amps. While less common than 60 and 100, I think there are 75 and 90 amp breakers available.

You want cable rated for underground. You could use UF direct burial or THWN in conduit, but others will probably have better info for you.

Will you need to run 4 conductors -- 2 hot, 1 neutral, 1 ground to meet the rules? Probably. Whether your on-the-pole main breaker lets you size based on service entrance rules, I don't know. But I am thinking you will need at least #2 copper, but if 60C rules apply, #2 copper is only rated for 95 amps. You might search for "310.15(b)(16)" uf thwn in your favorite search engine. http://www.ecmag.com/section/codes-standards/sizing-conductors

I don't know what all you need. I am trying to provide some things that may help you a bit in planning.

 

[Sponsor]

 

[DonL]

Did you get a permit ? Will your install be inspected ?

Good Luck on your project.

 

[Bruce09]

Figure 50 amp circuit for the welder? 40. I know it states 40 amp breaker in my photo, but I can't wrap my head around 12awg wire powering something wired for 220v. But I haven't the time for electrical theory, especially since the less confusion the better. I may be misinterpreting that chart? You guessed 50 so 40 isn't that far off, so I hope that answers your question on that portion.

You may want to get figures on the model you are planning.
It's a Lincoln mp-210 multiprocess, stick, tig, mig. I have downloaded all the info for that welder and have decided this will suit my needs. Any info you need about the welder, I got that covered and placed am order earlier.


Figure 12 amps for the 120 V AC AC. If you made that air conditioner 240 v, it would draw half as many amps for a given size.

OK, now I want to be sure you know that nothing I say is meant to question you or to come off as a smart @$$. I am definitely way out of my league with electricity lingo. Are you telling me I'd save my usage by somehow wiring a 120 ac unit to convert it to a 230v unit, or am I over thinking and u mean to purchase a 230 volt ac? Hope that doesn't sound ignorant, I'm just trying to understand because I'm all for using half of the power.

Maybe 20 amps for everything else? I think so, I've done everything from a drop cord for years by plugging into one of my 20 amp 12awg receptacles in my home and never tripped anything.

So 60 amps would not be enough. 100 would give some extra margin for future growth. #6 aluminum would not be enough for even 60 amps. While less common than 60 and 100, I think there are 75 and 90 amp breakers available.

I have no problems with purchasing a 100 amp subpanel. It's my understanding that I could buy a 125 amp. Or greater, not that it's needed but future expansion is always a possibility. I found a load center value pack that comes with breakers, can I put a 40 amp in this load center along with the 20s? Meaning, it looks like this panel only takes the smaller thin breakers rather than the bigger double ones. Please excuse the photos being out of order, I'm scared to delete one it may remove them all.

You want cable rated for underground. You could use UF direct burial or THWN in conduit, but others will probably have better info for you.

Will you need to run 4 conductors -- 2 hot, 1 neutral, 1 ground to meet the rules? Probably.
4 conductors meaning 4 wires? I know I sound like I shouldn't be doing this with the little knowledge I have but trust me, I'll catch up. I've already learned a lot from this one post, thanks..

Whether your on-the-pole main breaker lets you size based on service entrance rules, I don't know.
OK, kinda lost me there but I can snap some pics of my pole and the inside of my panel box outside. Inside the door with breakers. It's my understanding that when I kill the main breaker at the pole, the breaker box will not be powered? Or will I have to have the electric Co op come and pull the meter?
Don't worry, I guarantee you I won't put myself anywhere around anything unless I'm absolutely 100% sure it's safe.

But I am thinking you will need at least #2 copper, but if 60C rules apply, #2 copper is only rated for 95 amps. You might search for "310.15(b)(16)" uf thwn in your favorite search engine. http://www.ecmag.com/section/codes-standards/sizing-conductors

I don't know what all you need. I am trying to provide some things that may help you a bit in planning.

You have helped immensely! It's very much appreciated to get this information to make sure I'm doing right.

And for something like this I'm sure a permit and inspection is required, I wasn't going that route but it would be the best thing to do especially since it involves something that if isn't up to pay could Bite me in the future. I just live so far out in the sticks that pulling permits and stuff like that just doesn't seem as mandatory as it would if I was in public view. But I'm not against it if it'd be crazy to not have it inspected.

 

[Jadnashua]

A subpanel has the neutral and ground busses completely separate...a main panel has them tied together which is one reason why you need a 4-wire cable feeding the subpanel in the outbuilding. And, it also needs its own ground rods. You may need to buy the optional separate bus bar for the panel to make it work right and pass code. How deep the cable needs to be buried depends (you should check) but figure at least 18" as typical. You don't want to accidentally damage it.

 

[Bruce09]

I'm gonna do a little further research, and try to put together a good combination of materials that yall have mentioned, to where I can be a little more organized and familiar with the basics before I bite off more than I can chew. I thought mechanics had tough jobs, but I'm learning really quick there's more to this than burying some wire and buying a panel, a sack of wire nuts and a roll of electrical tape. I need to step back and get organized for this one. I'll get it together and lay out a game plan to where yall can correct things I got wrong or forgot. I'll get prepared and quit acting like someone should give me a list where I can run pick up everything and get home and suddenly understand all that goes into this.

 

[Reach4]

I am not an electrician. I was trying to make a few comments and try to give you some terms that you might search with.

Let me explain the air conditioner comment. If I have an air conditioner that consumes 1200 (corrected) watts, I could get one that draws 10 amps from 120 VAC or a different one that draws 5 amps from 240 volts. I pay by the watts multiplied by time. I run wires sized based on the amps.

On the other hand, if you have the 120 VAC air conditioner on the opposite leg of the power from the utility outlets, the current demand for wires would be the largest of the two 120 VAC loads.

The size of the wire you need to feed to the sub panel is determined by the breaker in the main panel that feeds the sub panel rather than the rating of the breaker itself. In other words, if you use a 100 subpanel rated for 100 amps, but have a 60 amp breaker in the main panel, the wires to the subpanel need to be enough for 60.

 

[Bruce09]

I really hope no offense was taken from anything I said, I've come to the conclusion that I may of jumped into this before I was aware of the basics. I really appreciate your information and learned quite a few things from your comments. I just clearly need to be able to understand more about this before I try and tackle it.

 

[Bruce09]

Is the subpanel I posted above a good choice for my situation? And I've been outside looking over the 6awg service wire I have and noticed it has places where the coating is gone and showing bare wire. I wasn't aware of that earlier so I'm definitely going to get 80' of supply wire instead of using that 6awg.

 

[DonL]

I am not an electrician. I was trying to make a few comments and try to give you some terms that you might search with.

Let me explain the air conditioner comment. If I have an air conditioner that consumes 12000 watts, I could get one that draws 10 amps from 120 VAC or a different one that draws 5 amps from 240 volts. I pay by the watts multiplied by time. I run wires sized based on the amps.

That is a good thing, with a math calculation like that.

Sorry, Just could not resist. My Bad.


P=I*E

 

[Bruce09]

"if you have a welder, that you may weld both inside and outside, and if your garage is large enough to make distance a consideration limiting your welder cord length, then a trick of the trade may be used. An article in the code allows you to install two welder plugs in opposite ends of your garage, and install both welder plugs on the same 60 amp circuit for an arc style welder, or even a 240 volt wire welder that is 20 amp rated. The reason you can do this is that you most likely would only have one welder, and one person welding. This should be considered as a non-coincidental load as referred in Article 220-21 allowing both welder plugs on the same circuit without consideration of making those two welder plug locations bigger but just considering them as one welder load as an either or scenario."
This is something that fits my needs, is this still valid, or has this been changed?

The following is in my own words and isn't quotes from things I've copied and pasted. These are statements that I THINK is correct from how I've interpreted things I've read that someone has said, or has quoted from nec. If I'm wrong, please let me know.

I can buy 7-20 amp standard receptacles and 1-20 amp gfci receptacle and use 12/2 solid copper wire from subpanel to receptacles, from a 20 amp breaker inside my subpanel.

I'm going to use 2-2 bulb 4' t8 florescent light fixtures with a total wattage being 64. I'm also going to use 4-60watt led bulbs, 2 outside, 2 inside. I am going to have two switches inside the entrance door, one for interior, one for exterior lights. I can run all of this from one 20 amp breaker in my subpanel. It doesn't seem to me I can run my lights and receptacles from one 20 amp breaker in my subpanel but from my understanding this is OK?

A 100 amp breaker is designed to only hold 100 amps worth of breakers no matter how many breakers you use, as long as all of them do not exceed 100 amps. So I could have a 70 amp breaker for my welder, and one 20 amp breaker for my lights and receptacles?

Can I use a 30 amp breaker instead of a 20 amp breaker for lights and receptacles as long as my feeder wire is correct for the length of run with voltage drop considered for 100 amps?
Common sense is great, I'm trying to think that way but I may be wrong. If I have a 200 amp main I'm feeding my detached shop and my house with, I need to make sure I do not exceed 200 amps worth of breakers in both subpanel, my home and my shop.

My main panel is 200 amp below the service entrance. I have 6 spaces left. I'm gonna buy a 100 amp breaker for the main panel, I'm gonna bury 80 foot of 4awg 3 wire copper and use an 8' ground rod at shop and can't use anything smaller than a naked, solid, 8 gauge copper wire. This is all alot to organize and consider. There's so many different accepted or not accepted variations. I have plastic boxes I've bought on sale for less than a dollar when I seen them on sale. I've just found out those only are OK to use for a finished sheet rock wall, so now I'm gonna have to go buy metal switch and receptacle boxes and covers, drill holes in 2x4s and put my wire inside some type of conduit.

My florescent lights aren't hardwired, they're designed to plug into an outlet. Can I cut the cord and wire it to my feeder wire? I'm sure that's not the proper way to do it but with an uninsulated metal roof can I put receptacles overhead to plug in my lights? Condensation in my mind could be a factor so any and all help is appreciated.

 

[Jadnashua]

The combined amperage of the cb in the subpanel could easily exceed the rating of the cb feeding it...this is normal UNLESS you typically would be actually using that much power! If I look at my panels, I only have 100A coming in, and there is easily over that in protected circuits after it. I've never tripped my main breaker, but in theory, if everything was on simultaneously, it would.

You can run lights and receptacles on the same breaker as long as your normal load is not going to trip it. Many people, especially in a shop, may find that having the lights and receptacles separate is a good idea so if you trip it using a tool, or something, you aren't in the dark.

This might get messy and I'm not sure you can get it to work, but you might be able to run 12-3 and a 240vac GFCI breaker, and then split each receptacle, so that each half had its own power. This works fine with a non-GFCI circuit, but I'm not sure you can get it to work when protected via GFCI, at least easily or with 12-3 - it wouldn't be hard with 12-2 and two breakers and GFCI for feed-through, or two 120vac GFCI breakers.

 

[Bruce09]

Many people, especially in a shop, may find that having the lights and receptacles separate is a good idea so if you trip it using a tool, or something, you aren't in the dark

Straightforward good common sense that a rookie like myself would of had to learned the hard way. Great point..

The combined amperage of the cb in the subpanel could easily exceed the rating of the cb feeding it...this is normal

makes perfect sense, as long as you aren't pulling all of those breakers at once like you said..

The last part of your comment is a little foreign to me as far as splitting it, so now that it's clear I'll need to put two separate breakers in for lights and receptacles, I'd only need one gfci receptacle at the start or finish of the circuit and that'd make it simplier for me to do right? Will a gfci breaker eliminate the need for gfci outlets? U may of answered that but that's the only thing you've said I'm scratching my head about.

 

[DonL]

In theory a GFCI on the welder should not trip. In the real world you may get false breaker trips.

And if you have any AFCI's in your house they may trip also, When welding.


Those electrons are funny sometimes.

 

[Bruce09]

Not sure if I have any of those or not. I bought all my stuff today. I have the option of direct burying 80' of 2 awg aluminum 3 service wire, or can run it overhead. It seems it'd be easier to run it overhead. I am lucky enough to have a telephone pole buried 4' in the ground directly next to my shop. I got it 2 years ago to hang deer and hogs from for processing. I didn't remove the grey ceramic roller at the top back then so that's one less thing to buy. The guy at Lowes seemed knowledgeable about this, but, it is OK to bury this stuff without putting it in conduit? If I decide to put it overhead, other than following a certain height, what other issues will I run into? To make a long post short, which one is best, or is it the same? Personal choice? 80' with a matlock, three foot deep has me leaning towards overhead. That's how my main is fed, so as of now I don't see any cons other than the cost of things I may have to place on the pole. Weather head? I got a 20amp Cooper gfci, 6 Cooper 20 amp receptacles, a heavy duty single pole switch, homeline 125 amp 6 circuit, 12 space interior subpanel, a single double 20 amp breaker, and a big fat 60 amp for the welder. A 4' shop light and a set of paddle drills. Still gotta get 12/2 copper for wiring inside and the right amount of 4 awg copper wire for the two 230v receptacles. Oh, and I found some 400 lumen, 5000k led Christmas holiday lights for outdoor wet locations that I'm gonna use for porch lights. How about the shop lights, they have a plug, should I put a receptacle on the rafters or can I hard wire them in my 20 amp light circuit? Thanks to you guys I'll be rolling up the drop cords and flipping switches..

 

[Jadnashua]

When using GFCI's, you get the protection after you insert the thing which can be either at the panel, or the first receptacle (they also make separate ones without receptacles that fit into boxes) in the daisy-chain IF the GFCI has both line and load terminals (most do, not all). You'd feed the downstream devices from the load side and put the input power to the line side.

On a shared neutral circuit, you can get by with only running 12-3 and have essentially two (mostly) independent circuits (rather than running two 12-2 cables). This can be handy to feed each half of a receptacle with its own circuit. Because the power leads are opposite in phase, any power going back through the neutral cancels out, so it isn't double, and the same size neutral works...it can never be bigger than the breaker feeding it, and if the power being used on both sides is equal, the current in the neutral is zero. But, you might have a problem using a GFCI doing this. A GFCI works by measuring the power out verses that returning and comparing them. IF it detects a difference, it trips. This means that some of the current leaked somewhere it shouldn't have. A suitable GFCI breaker might work, but two individual GFCI receptacles may not.

 

[JWelectric]

Must be 4 wire between buildings

 

[DonL]

Must be 4 wire between buildings

Where have you been JW ?

You need to inspect these threads better, and quit slacking on us (lol), before people get hurt.

I hope all is well for you and your family.

 

[Bruce09]

Something has come up and changed my direction for now, I'll make this brief so I won't over complicate it because it should be simple. I have buried, in pvc uf 12/2 cu gray wire. Me and a friend did it 16 years ago and not sure why we buried it in pvc but it is what it is. It is my understanding that I am under 2008 nec. It's also my understanding that I can (for now) wire my lights and receptacles from the main, without a sub in the shop. I go into the building with a Junction box, not sure of the term but it is rectangular, join my feed to my wiring and I'm good? For now at least I'm gonna hold off on the 220 outlets and subpanel and welder. I have a black, white, and naked solid ground. I have two lights and for now I'm gonna do 6 receptacles, one switch, and one gfci at the start so I can allow all of them to be gfci so to speak. I like the idea of the armored cable but I can't put it on top of my 2x4s I don't think. I can't put RomexA® in conduit from what I've read, and I can't run RomexA® through the middle of my 2xs unless it's... I really don't know about that but it appears I can go get pvc schedule 80 and put three separate wires in that and wire it all like that. I've avoided asking this question because I didn't wanna appear lazy, so now I have two options, hire an electrician, or somehow talk one if you guys into explaining this in terms that a dummy could understand. Just when I think I've got a grasp on the basics, I'm faced with another term that looks foreign. Duplex receptacles are for wiring more than one receptacles? That doesn't seem right, can't you branch out from the ones that aren't Duplex and cost 69 cents at Lowes? I have a switch that has a receptacle under it, does that switch control only that one plug? Probably not, I'm sure I could use that one switch for more but can I use it as the disconnect switch? I have seen diagrams on top of diagrams and jumpers, I'm gonna be honest, I'm confused as hell.

 

[Jadnashua]

A duplex receptacle has two outlets...you can break the tabs between them, and wire each one up separately which would allow you to say run two independent 12A devices on one duplex receptacle. When running to a subpanel, you need 2-hot, one neutral, and one ground wire. I think you are right, though, and that a single branch circuit to an outbuilding is treated differently than where you have a subpanel. Any wire run underground should be rated for underground use even if it is protected from physical damage with something.