OT - Wiring my Workshop, Input on 220v needed

[Ed S.]

Was just reading the thread on stick welders, which prompted me to "tap" into some of that knowledge for the workshop I'm building (and am now wiring) inside my big machine shed.

I have 3 phase to the barn, and have replaced the old 60 amp fuse box with a 100 amp panel. Would like to run two 220v lines, one for an eventual stick welder, and one for an eventual 60-80 gal. two-stage compressor.

First, I'm assuming I should use four-prong (grounded) outlets - I presume if I were to buy an older used welder, it would use the three-prong outlet, though?

And based on the other thread, it sounds like using at least a 50 amp breaker on the welder would be good... As I don't have the equipment yet, I can't read the tags or manuals to see what they would call for... maybe I should just pull the wire and wait to get the breaker?

Is there a "standard" breaker size for a 60-80 gal. two-stage compressor? Tech specs are scarce when googling, but I did see a couple that indicated a draw of around 30 amps (so I presume a 40 or 50 amp breaker?).

Lots of questions, not much detail, I know... just curious as the the general direction to take this while I'm still pulling wire.

So I guess the actual question is, "How would you wire yours if you were doing it anew?"

es

 

[DollarBill]

Ed are you sure you have 3 phase? Extraordinary as 3 phase is usually only seen in industrial construction.

Or do you have a friend at the power company :lol:

 

[BillM (OH)]

Ed:
When I did mine I used a 60 amp breaker for the old
welder, and a 30 amp breaker for my single stage
compressor. The size of the breaker will depend on the wire
size you are using, which will depend on the motor draw, so
you really need to know the motor HP and amp draw before
you pull the wire and install the breakers.

 

[Jim in Western MI]

This may be inherently known without being said (written), but the breaker amp rating is only one of the two factors. The wire size is the real player..., 30 amp-size 10 wire, 40 amp-size 8 wire, and 50 amp-size 6 wire. The latter is the same as most electric ranges, the wire is big (and expensive).

 

[Ed S.]

(quoted from post at 06:52:08 01/25/11) Ed are you sure you have 3 phase? Extraordinary as 3 phase is usually only seen in industrial construction.

Or do you have a friend at the power company :lol:

You know, that's a good question! I assumed because I have two hot wires and a neutral coming into the barn that it was three phase, but my understanding is probably wrong, it sounds like. We do have 400 amp service on the farm, as I believe they used to run dryers, etc. back when it was an active large farm.

How can you tell what you have?

es

 

[TheOldHokie]

(quoted from post at 09:14:59 01/25/11) Was just reading the thread on stick welders, which prompted me to "tap" into some of that knowledge for the workshop I'm building (and am now wiring) inside my big machine shed.

I have 3 phase to the barn, and have replaced the old 60 amp fuse box with a 100 amp panel. Would like to run two 220v lines, one for an eventual stick welder, and one for an eventual 60-80 gal. two-stage compressor.

First, I'm assuming I should use four-prong (grounded) outlets - I presume if I were to buy an older used welder, it would use the three-prong outlet, though?

And based on the other thread, it sounds like using at least a 50 amp breaker on the welder would be good... As I don't have the equipment yet, I can't read the tags or manuals to see what they would call for... maybe I should just pull the wire and wait to get the breaker?

Is there a "standard" breaker size for a 60-80 gal. two-stage compressor? Tech specs are scarce when googling, but I did see a couple that indicated a draw of around 30 amps (so I presume a 40 or 50 amp breaker?).

Lots of questions, not much detail, I know... just curious as the the general direction to take this while I'm still pulling wire.

So I guess the actual question is, "How would you wire yours if you were doing it anew?"

es

I would die for POCO 3 phase to my shop!!!! You can run some big electric motors with 3P!!! The biggest single phase electric motor you are likely to see is 5HP. I have to brew up my own 3P for my machine tools using a whole shop rotary phase converter I built:

I found a "little" 5HP three phase compressor nearby and bought it for $500 including the stand alone industrial air dryer that it had with it. Unfortunately my phase converter doesn't run 24 x 7 so I had to swap out the big old 5hp Lincoln motor for a 5hp single phase unit half the size. Still works wonderfully but I'm sure the 1P motor you see here won't last nearly as long as the old Lincoln. It is currently on casters because I just moved it out of teh old shop and I have it plugged into a 220V/30A circuit that I use for the lathe behind it. The smaller motors used on some of the stuff I see at TSC have pretty hefty startup draws so they might not.

As for the welder - same thing goes for 3P - if you can find a used 3P unit you can usally get a lot more machine for your $$$. Down side is if you ever move to some place without 3P service you are going to be SOL.

A single phase 220V circuit for an electric motor or welder has no neutral so it uses two current carrying conductors and a grounded conductor - 3 prong plug. You only need the fourth neutral conductor and 4 prong plug if the equipment also has a 120V component in it (like the light in a clothes dryer). Wire your welder circuit with #6 THHN wire (not cheap) run in conduit and it will handle anything up to 70A. You can put whatever size breaker is appropriate in the box when the time comes.

If you are not comfortable with any of this get some assistance from someone with more experience and knowledge.

TOH

 

[Ed S.]

Good info on the wire sizing, Bill and Jim... As I'll need to button things up well before I buy the tools, I'll have to make some assumptions on what I will eventually need. And yes, I remember the thick wiring for the range and electric dryer, and that they were expensive!

es

 

[Ed S.]

That's helpful, TOH... Now I'm beginning to understand what questions to ask. I'm comfortable with doing the work, once I understand what I need to do.

es

 

[TheOldHokie]

(quoted from post at 10:51:35 01/25/11)

(quoted from post at 06:52:08 01/25/11) Ed are you sure you have 3 phase? Extraordinary as 3 phase is usually only seen in industrial construction.

Or do you have a friend at the power company :lol:

You know, that's a good question! I assumed because I have two hot wires and a neutral coming into the barn that it was three phase, but my understanding is probably wrong, it sounds like. We do have 400 amp service on the farm, as I believe they used to run dryers, etc. back when it was an active large farm.

How can you tell what you have?

es

From that description you have 400A single phase service - same as me - so ignore all that 3P stuff I posted. Quite a few farms around here have 3P for running big motors and such so it's not unusual to see it in an AG setting.

TOH

 

[RogerN]

Ed, It's very possible you have three phase wiring. If the working farm had grain bins and dryers, to my knowledge, most of those needed 3-phase.

 

[JMOR]

(quoted from post at 11:02:52 01/25/11)

(quoted from post at 10:51:35 01/25/11)

(quoted from post at 06:52:08 01/25/11) Ed are you sure you have 3 phase? Extraordinary as 3 phase is usually only seen in industrial construction.

Or do you have a friend at the power company :lol:

You know, that's a good question! I assumed because I have two hot wires and a neutral coming into the barn that it was three phase, but my understanding is probably wrong, it sounds like. We do have 400 amp service on the farm, as I believe they used to run dryers, etc. back when it was an active large farm.

How can you tell what you have?

es

From that description you have 400A single phase service - same as me - so ignore all that 3P stuff I posted. Quite a few farms around here have 3P for running big motors and such so it's not unusual to see it in an AG setting.

TOH

phase has 3 hot wires, virtually always accompanied by a neutral, thus making a total of 4 wires coming to the meter & if you read the face of the meter it will very likely have the words 'three phase' or 'single phase' on it. There are exceptions to everything, except death.

 

[R Geiger]

I do beieve that it would pay to hire an electrican to come out and check out what you have and what you will need. It will be money well spent and keep you safe. Do you have to have an electrical building permit before you do the work? I had to have one here in Oregon befoe I wired my shop and the inspector was a real big help.

 

[TheOldHokie]

(quoted from post at 11:32:29 01/25/11)

(quoted from post at 11:02:52 01/25/11)

(quoted from post at 10:51:35 01/25/11)

(quoted from post at 06:52:08 01/25/11) Ed are you sure you have 3 phase? Extraordinary as 3 phase is usually only seen in industrial construction.

Or do you have a friend at the power company :lol:

You know, that's a good question! I assumed because I have two hot wires and a neutral coming into the barn that it was three phase, but my understanding is probably wrong, it sounds like. We do have 400 amp service on the farm, as I believe they used to run dryers, etc. back when it was an active large farm.

How can you tell what you have?

es

From that description you have 400A single phase service - same as me - so ignore all that 3P stuff I posted. Quite a few farms around here have 3P for running big motors and such so it's not unusual to see it in an AG setting.

TOH

phase has 3 hot wires, virtually always accompanied by a neutral, thus making a total of 4 wires coming to the meter & if you read the face of the meter it will very likely have the words 'three phase' or 'single phase' on it. There are exceptions to everything, except death.

Help me out JMOR - my experience with POCO provided 3 phase sevice is nil. Three phase Wye service has 3 phase conductors and a neutral conductor coming rom the POCO transformer. But there is no neutral conductor on basic 3 phase Delta service - just 3 phase conductors. If you need a neutral you get it with a center tap transformer installed on two legs of the Delta (possibly by the POCO)?

And Wye/Delta service differ significantly on what you get for line to line voltages? This is why I was having trouble in my initial reply to Ed - I suspected he had Wye service for lighting circuits.

Where's JohnNOX when we need him - he made his living doing this stuff for PEPCO.

TOH

 

[Jock (OR)]

The easiest way to tell if you have 3 phase power is to count the number of wires that pass through the main breaker. If there are two, you have single phase. If there are three, you have three phase.

Check out your local library for a book called "Practical Electrical Wiring" by Herbert Richter. It is a textbook for electricians, and contains all sorts of information, including tables that help you determine the wiring for motors. It is well-written and understandable (unlike many textbooks) and is easy to use. There are several editions, but even the 20-year old editions are useful as the basics have not changed.

Another good book is "Ugly's Electrical Reference" which I have seen at Home Depot. It has a much more limited scope, but is pretty inexpensive.

 

[Jim in Western MI]

Most non-commercial electric clothes dryers like we have in homes are 30 amp and use 10-2 wires..., just a bit larger than the 12-2G used for lights and receptacles. I don't have a grain or peanut dryer, but I expect they are MUCH larger and most are 3 phase if available.

 

[JMOR]

Precisely why I ended by saying, there are exceptions to everything except death.
There are many 3 phase connection schemes/arrangements. Over time the number of variants seem to have decreased, but in various places some of the more obscure still exist. Books are written on preferences for one or another, depending on the loads being served, such as mostly single phase with a little 3 phase load or mostly 3 phase with a little single phase, etc. IF there is a need for both 3 phase and single phase, then a wye can be used with 120 to center/neutral and 208 phase to phase, or a delta or open-delta with N to either of two phases being 120 and phase to phase being 240 and caution exercised as neutral to that 3rd phase (high-leg or wild-leg) will be 208. These are found often, but there are many out there.

 

[lha]

If there are 3 buss bars in the breaker panel,then you have 3ph.If you have 3 pole breakers,then you have 3ph.If you have only 2 hots and a "not",then you have single ph power,which is adequate for almost any need.As stated,unless you have had some pretty big stuff,that's all you'll need.---lha

 

[old]

I to would love to have 3 phase in my shop but the cost of it is not worth it. Just to bring it in would cost a few thousand and then I would not use it enough to even come close to being worth the cost

 

[TheOldHokie]

(quoted from post at 12:28:10 01/25/11) Precisely why I ended by saying, there are exceptions to everything except death.
There are many 3 phase connection schemes/arrangements. Over time the number of variants seem to have decreased, but in various places some of the more obscure still exist. Books are written on preferences for one or another, depending on the loads being served, such as mostly single phase with a little 3 phase load or mostly 3 phase with a little single phase, etc. IF there is a need for both 3 phase and single phase, then a wye can be used with 120 to center/neutral and 208 phase to phase, or a delta or open-delta with N to either of two phases being 120 and phase to phase being 240 and caution exercised as neutral to that 3rd phase (high-leg or wild-leg) will be 208. These are found often, but there are many out there.

Bingo - the delta with wild leg configuration was the one I was having trouble dredging out of the memory banks....

TOH

 

[36 Coupe]

Theres a 3 phase line in front of my house.rural area.There was a cedar mill close to the sub station 40 years ago.

 

[Ed S.]

If you have only 2 hots and a "not"

That's what I have, so single phase. I love tossing out questions like this - always get an education with the responses .

I've got a wiring book around somewhere, and will dig it out for review before I mess with anything. We're very rural, so no permits... but I also don't have a problem having an expert come in when I'm not sure, or want my work checked.

es

 

[Jock (OR)]

Our POCO only provides 3 phase to smaller users in the form of 240V delta. This means that there are four wires: 3 feed wires and one neutral wire. The ground wire is not considered part of the service wiring.

The drawback of this type of service it that if you connect one of the the feed wires to neutral, you normally get 120V, for lights, etc. But with the delta service, one of the feed wires (the "wild leg) will give you 208V if connected to neutral!!! Our local service provider requires the wild leg to be marked with orange, but if you aren't inside the box, you'll never see it.

I'm wiring a new shop using this system, and it will be OK, except that the meter reading will show more power used than I am actually using because it measures the peak of the unbalanced load, giving no "credit" to the lower loading on the "wild leg" which will have only 240V loads on it. I am going to install a 240V/120V single phase transformer on the "wild leg" so I can run enough single phase circuits to balance the load. At the current electricity rates, it is worth the investment!

 

[weaveman01]

Hey Ed- I'm not taking a shot at you, but by the general description of you're questions, you may want to invest a little more time in the learning of AC theory and installation, or bribe someone from CAT that is an electrician to stop by the house. Don't listen to the kid at home depot that is an expert because he stocks the electrical department either. Or the guy that does carpentry, roofing, and electrical and anything else he can talk you into paying for. These people usually know enough to make it dangerous (think fire or electrical shock).

You either have 240 volt which would be single phase, or 208 volt which would be 3 phase. The main breaker will give you that answer too, as 240 volt will have 2 wires going thru it and 208 volt will have 3 wires going thru it. Also, there are alot of variables when it comes to sizing wire to equipment. Distance, conduit it is run in, insulation of the wire, etc..

The point is, for you're safety, you're childrens safety, and the building's safety, be sure to get one qualified opinion, and don't start making changes based on what worked for a farmer one time. I've been a commercial and industrial electrician for 15 years, and have even installed a few of them big CAT generators you're company sells, and the scariest things that I have seen is when helping friends with their electrical that was farmerized by someone else.



Electricity can be done a variety of ways, but there is a reason that faulty electrical installations are the #1 source of house fires.

 

[TheOldHokie]

(quoted from post at 14:45:14 01/25/11) Our POCO only provides 3 phase to smaller users in the form of 240V delta. This means that there are four wires: 3 feed wires and one neutral wire. The ground wire is not considered part of the service wiring.

The drawback of this type of service it that if you connect one of the the feed wires to neutral, you normally get 120V, for lights, etc. But with the delta service, one of the feed wires (the "wild leg) will give you 208V if connected to neutral!!! Our local service provider requires the wild leg to be marked with orange, but if you aren't inside the box, you'll never see it.

I'm wiring a new shop using this system, and it will be OK, except that the meter reading will show more power used than I am actually using because it measures the peak of the unbalanced load, giving no "credit" to the lower loading on the "wild leg" which will have only 240V loads on it. I am going to install a 240V/120V single phase transformer on the "wild leg" so I can run enough single phase circuits to balance the load. At the current electricity rates, it is worth the investment!

Did you consider a phase converter instead of POCO service Jock? The POCO quote I got for 3P vs a heavy up to 400A 1P was very substantial. And the 3P bumped me into higher industrial rates for my home consumption!

I have a 20HP RPC feeding a 3P panel that powers all the 3P machine tools in my shop. I could run the air compressor off that panel as well but I opted to replace that 5HP motor with a 1P one so I didn't need to keep the RPC running just for it. RPC works great and it uses 2 10HP idlers - I only start the second if I need more juice than one can sustain. Here's a picture ofthe largest single load in my shop - a Cincy mill - alongside the 100A RPC control panel and 3P breaker panel that feeds the 3P circuits in the shop. The mill has a 10HP main spindle motor, a 3HP motor on the vertical head, and a 3 HP table motor and will run off a single idler if I don't power up the main spindle. That picture was taken while I was wiring everything up and things aren't nearly as clean or unclutttered now ;-) Any branch circuit tied to that wild leg should be marked in orange everywhere it goes in your shop!

TOH

 

[Jock (OR)]

The POCO made me a pretty good deal, since three phase runs right through my front yard. I have plenty of experience with 480 three phase from my rock quarry. I tried to get 480V but the POCO doesn't have any option for that except heavy industrial. They give me residential rates for the 240V three phase service. I guess it is because they supply it to apartment buildings.

It would be easier for me if they I could get 480V, since I already have a 45KVA 480-208/120V transformer. I looked around for a 115KVA 480/240V transformer to bump up the feed voltage, but couldn't find one for an affordable price.

I would need a pretty big phase converter, since my largest load is currently 7.5HP, and expect to add at least one 10HP motor later! I don't like the noise of the rotary converters, and the solid state units are more expensive than the POCO contract for the three phase.

By the way, the POCO started out expensive, but when they found out that I knew what I was doing, and that I was willing to put a phase converter on a 400A single phase service, they came down a lot! They realize that unbalanced loads are a big problem, and want to get away from them. They just want to make the most money if they can. BTW, Warren Buffet owns my POCO, so that tells you something.

 

[TheOldHokie]

(quoted from post at 16:21:19 01/25/11) The POCO made me a pretty good deal, since three phase runs right through my front yard. I have plenty of experience with 480 three phase from my rock quarry. I tried to get 480V but the POCO doesn't have any option for that except heavy industrial. They give me residential rates for the 240V three phase service. I guess it is because they supply it to apartment buildings.

It would be easier for me if they I could get 480V, since I already have a 45KVA 480-208/120V transformer. I looked around for a 115KVA 480/240V transformer to bump up the feed voltage, but couldn't find one for an affordable price.

I would need a pretty big phase converter, since my largest load is currently 7.5HP, and expect to add at least one 10HP motor later! I don't like the noise of the rotary converters, and the solid state units are more expensive than the POCO contract for the three phase.

By the way, the POCO started out expensive, but when they found out that I knew what I was doing, and that I was willing to put a phase converter on a 400A single phase service, they came down a lot! They realize that unbalanced loads are a big problem, and want to get away from them. They just want to make the most money if they can. BTW, Warren Buffet owns my POCO, so that tells you something.

I hear you on the RPC noise issue - that's why my idlers are going outside in thier own little box come spring. I didn't push my POCO on pricing because I didn't want to attract a lot of attention to my plans for the RPC :roll: When I built my house one of the deals I worked with them was granting them an easement to bring their underground HV lines across my property and install a much larger than needed transformer next to my house in the event they ever needed to extend the line to the properties behind me. So it would have been very easy for them to give me 3P if they were so inclined. Does Warren have a piece of PEPCO :wink:

TOH

 

[36 Coupe]

You need 3 hot wires plus a ground wire to have 3 phase power.

 

[Jimmyjack]

What a beautiful shop! When I see one like that I just get depressed. After I retired I swore my shop would get to look like that, and it just never happens. My hats off to you TOH

 

[TheOldHokie]

(quoted from post at 19:17:19 01/25/11) What a beautiful shop! When I see one like that I just get depressed. After I retired I swore my shop would get to look like that, and it just never happens. My hats off to you TOH

Put your hat back on Jimmy - it doens't look anywhere near that nice now

TOH

 

[Plane Bart]

Ed where are you in Illinos or better yet how far are you from Scott Air Force base in Shilo Illinois I am a master electrician if you are reasonably close I could swing by this weekend got nothing better to do.
it sound like your best bet would be to add a sub panel in the new building if you are going to run a welder and compressor together you would probally need a 100 amp sub panel out in the new building.
for that you would need space in your main panel for a 2 pole breaker 100a
A 1" conduit, #2 copper wire (3 needed 2 hots and a neutral {white wire}], and a #8 Green ground
at the sub panel being it is a seperate building you will need to add a ground rod and a #6 copper conductor to ground bar in the panel.
50Amp 240 volt circuit for most stick welders, 30 amp 240 volt for most 240 volt air compressors.
if you have any questions shoot me an e-mail with your contact number and I can call you.
Bart

 

[Hobo,NC]

Why limit it to a 100 amp service,,, why not a 200 amp service... With a 100 amp service 100 amps is all you will ever have available,,, you can max it out real fast with a good welder and a good compression work'n at the same time.......

 

[Ed S.]

@weaveman01 - I hear you and will do some more self-education before jumping into something before I fully understand what to do - up to and including calling in pro help if I feel in over my head. I'll check the voltage at the panel, but after reading these comments and googling a bit, I'm 99% sure it's single phase now that I understand the difference. The old fusebox had three feed wires coming into the box - two hot and a neutral (black insulation), which, after hooking everything up to the new panel, has all existing circuits working fine.

@Plane Bart - We're NW of Peoria, about 4 hours from you... the workshop is just an 18'x24' room I'm building *inside* the machine shed, so it's really only a matter of replacing the old fusebox with a panel (already done) and running wire to the outlets and lights (also already done). The main thing I need to sort out is amps, wire size and 220v outlet ratings... both of which will be <25' from the panel. Once I know *what* to do, it won't take 30 minutes to do it. (c:

@Hobo - Already have the new 100 amp panel installed, so there's that... I did consider 200 amp, but my usage of the "big" stuff will be occasional... really didn't feel it was that necessary (I hope those are not 'famous last words').

@everyone else - thanks for the input and comments - educational as always!

es