Electrical service for a metalworking shop

[Bigredford]

I'm building a 40x100x17 shop. There will also be about 800 square feet of living space inside.

When I pulled my permits I selected a 400 amp service.

So far my three phase equipment is as follows...

A Gorton 1-22 Mastermill

2 Cincinnati Bickford drill presses. One has a 3 horsepower motor and the other has a 5 horse.

A Lincoln welder that has a three phase motor that spins a DC generator. 32 amps at 240 volts.

A 20 horse air compressor.

I plan to have a metal lathe or two in the not so distant future. I recently looked at a 20 horse American Pacemaker but only passed because I'd have to move it twice and store it outside until my shop is dried in. I have a addiction to old metalworking equipment.

Lighting will be 6 bulb t5 high bays. Not sure on quantity yet.

As far as heating is concerned I'll be using propane. Water heater may be electric.

Three phase is available to me. The line is about 6 telephone poles away from my driveway.

I like the thought of one service on my property and eventually feed the future house out of the shop service

How big should I go?

 

[LXCam]

Is there a question here I missed? If you're concerned about not having enough capacity you won't have a care in the world with the equipment you've listed even with a couple guys working with you. What it comes down too when sizing a service for a one man shop is what's the most load that will run simultaneously, lights/compressor/hvac/welder, etc?

But I'd suggest a VFD for that 20hp compressor maybe. That's a hell of a unit for a small shop. Got some pics?

 

[Bigredford]

I guess my real question is...if three phase is cost prohibitive will 400 amp single phase drive a big enough phase converter.

The compressor is a 3 cylinder 2 stage Worthington. One heck of a pump. Overkill? Yes. But the tank rotted out and it was going to go for scrap so I saved the pump and motor.

 

[wyliesdiesels]

Since youre looking into getting 3 phase from the PoCo and want to possibly feed the house with it in the future, there is quite a bit to consider here.

I see some of your equipment is 3 phase 240v. Is this equipment dual rated meaning it can run on 208v/240v or 240v/480v?

If it will only run on 240v, then you may have an issue as many PoCos are no longer installing new 240v delta service. I would ask your PoCo which flavors of 3 phase are available.

If they only install 208Y or 480Y (meaning no 240v Delta), then you will either need buck boost transformers for some equipment or a large step down transformer. If you feed the house with the 480v service you would need a step down transformer as well.

Having tranaformers energized all the time will mean paying for some extra electricity in the form of heat losses.

A 20HP 3 phase motor is gonna **** a lot of juice. @ 240v the NEC FLC is 54a.

 

[sberry]

200 is a lot cheaper. Get a modest air compressor unless you have a specific need for it. Same for the welder.

 

[Bigredford]

I had last talked to Georgia Power two years ago. At the time I wasn't sure how far away from the road my building would be. I had told the engineer I'd be willing to trench, lay conduit, supply and pull wire from the shop up to the road. Otherwise they wanted a 40' right of way to the building. Engineer said that it would cost little to hook up power. At the time I had asked about 200 amp 240v 3 phase service.

Building is about 400 feet from the road.

 

[wyliesdiesels]

I had last talked to Georgia Power two years ago. At the time I wasn't sure how far away from the road my building would be. I had told the engineer I'd be willing to trench, lay conduit, supply and pull wire from the shop up to the road. Otherwise they wanted a 40' right of way to the building. Engineer said that it would cost little to hook up power. At the time I had asked about 200 amp 240v 3 phase service.

Building is about 400 feet from the road.

Thats a hell of a run for secondary wire. Would need some very large wire to compensate for voltage drop.

I just browsed through GP's Blue book and they indeed offer new 240Delta service.

 

[nsula_country]

240V Delta would be the best option IF feeding house too.

Problems would be distance. Two services may be the better bet. We set the shop up with its own address for billing purposes. Our shop is about 700' from the 400A/320A 1P service feeding the house. Hence bit the bullet and paid POCO about $7000 to run about 800' of overhead to a pole about 80' from the shop. Pole xformer, pedestal at ground, ran underground to a 200A 1P pan on side of shop.

CT

 

[wyliesdiesels]

200 is a lot cheaper. Get a modest air compressor unless you have a specific need for it. Same for the welder.

Id be willing to bet that the air compressor is grossly overkill

 

[nsula_country]

Id be willing to bet that the air compressor is grossly overkill

Unless he sandblasts... My homemade 13 hp, 2 stage 2 cylinder 150 gallon compressor will go from 175 psi to about 80 psi on a 40 lb pressure pot load.

CT

 

[u3b3rg33k]

would a couple of these do?
https://emaxcompressor.com/products...le-phase-air-compressor/#product-features_tab

gotta love the low startup current.

 

[matt_i]

My free opinion is this: get your quote from the PoCo and then look at a Phase Perfect 10 or 20hp. Which is not cheap but it will do everything that utility 3 phase will do, at possibly a lower cost. Just feed it with 240vac single phase. Make sure you understand demand meters and if one will apply to you, if you go the utility route.

Its just me but I question the use of a compressor that big. Even a "little" 5 hp compressor running is like pouring money down the drain when you run it. Understandably cool piece of machinery but I'd just restore it and run it here and there unless you have a serious need (only one I could think of is sandblasting).

Its nearly impossible to draw full hp on a manual metal lathe without the toolbit being thermally grenaded into a chipped edge smoky mess that's producing a terrible finish. Love a big lathe but the amount of time one can spend on the opportunity to make massive chips is pretty small.

But whatever you do have fun. All it takes is money. And we can't take it with us.

 

[sberry]

5hp is kind of a standard. Small enough can be used on 100a service and big enough that it can be used for body work as well as run all the other basic air tools. 3hp was more popular back in the day for mechanics and 2 stage would run tools and air up truck tires, also back in the day lotso garages were on 60. Small for sandblast (so is 5 but better) but was light for body tools, sanding and wire wheels.

 

[Bigredford]

Only one machine I have is wired for 480. That would be the Gorton mill. The spindle motor can be rewired to 240 but there is some sort of rectifier for the power feeds and no idea what I'd have to change.

The older Cincinnati drill and the Lincoln welder are both 240 only. Only 3 motor leads.

The Lincoln uses a smaller circuit then my Miller Thunderbolt.

The plan for the compressor is to plumb it in with my 80 gallon CH and a 60 gallon tank. Only switch it on when needed. Otherwise run the 80 gallon on it's own.

If I ended up going the rotary phase converter path I'd probably build my own. Can get a used motor from work.

 

[sberry]

The Linc and the Tbolt use different type of circuit.

 

[4 FN 27]

I agree with Matt. Get a quote from the power company. See how it compares to a Phase Converter.

I did the math on mine, well as much as I could. I had 3 phase run to my place a 1/2 mile. They gave me a Time and Material bid. They wanted 100% upfront and refunded the balance one completed. Ended up getting 40% back.

The gamble was how much would I get back??? Didn't know at the time of ordering or installation of all the HVAC equipment and lighting. I speced everything at 480 on the HVAC side and the lights at 277.

The bonus I found out after the install was in this area 480 is considered Commercial and is billed at $0.01 less per KWH than residential. All my equipment used and new other than my VMC are all 480.

I ended up with a 400 amp 3-phase 480 Transformer. Plenty of power for what I have but I know I will never run short. The upfront cost was a little more having to step down to 120 but well worth it in my eyes. Cord Caps at 480 are much smaller thus a cost savings. The Cord Cap going to my 50 HP pump on the Water Jet @ 480 is the same size as the 10 HP motor on the VMC @ 220.

I really wanted 2 separate services from the power company. 480 3-phase and 120-240 single phase with separate meters but they would not do it.

Let us know what you end up doing.

Good luck!!!

 

[Aceman]

240v delta would be the best for what you're trying to do, but I would check with the power company to see if 3 phase kicks you up to the higher prices/fees of commercial metering.

If you still decide to go ahead with it, you'll spend more on the metering/panelboard side upfront for the 3 phase equipment, but it'll be far more flexible and a lot simpler down the road than phase converters and other workarounds for dealing with your 3 phase equipment.

Be aware, 240v delta does give you one phase that is 208v to neutral. It's not a big deal when you are aware of it, but if you have many line-neutral loads(120v) you may need to purchase a panel with more spaces since a third of the spaces are essentially unusable for 120v loads.

 

[DSMR]

If I had 3 phase available for my shop I would go with 480 and a transformer for 240 and 120 single phase. This would allow you the greatest flexibility.

 

[sberry]

I agree with Matt. Get a quote from the power company. See how it compares to a Phase Converter.

I did the math on mine, well as much as I could. I had 3 phase run to my place a 1/2 mile. They gave me a Time and Material bid. They wanted 100% upfront and refunded the balance one completed. Ended up getting 40% back.

The gamble was how much would I get back??? Didn't know at the time of ordering or installation of all the HVAC equipment and lighting. I speced everything at 480 on the HVAC side and the lights at 277.

The bonus I found out after the install was in this area 480 is considered Commercial and is billed at $0.01 less per KWH than residential. All my equipment used and new other than my VMC are all 480.

I ended up with a 400 amp 3-phase 480 Transformer. Plenty of power for what I have but I know I will never run short. The upfront cost was a little more having to step down to 120 but well worth it in my eyes. Cord Caps at 480 are much smaller thus a cost savings. The Cord Cap going to my 50 HP pump on the Water Jet @ 480 is the same size as the 10 HP motor on the VMC @ 220.

I really wanted 2 separate services from the power company. 480 3-phase and 120-240 single phase with separate meters but they would not do it.

Let us know what you end up doing.

Good luck!!!

likely a different budget here.

 

[Norcal]

If I had 3 phase available for my shop I would go with 480 and a transformer for 240 and 120 single phase. This would allow you the greatest flexibility.

If you don't have the load, it is a foolish route to take, there are much higher costs with 480V, as equipment costs more, transformer losses, & so on. Better to be supplied with 208Y/120V, or 2nd choice 120/240V 3Ø, plus 480V is one of the most dangerous voltages there is, if you eff up, your better off dead, so it should only be worked on by qualified people.

 

[DSMR]

If you don't have the load, it is a foolish route to take, there are much higher costs with 480V, as equipment costs more, transformer losses, & so on. Better to be supplied with 208Y/120V, or 2nd choice 120/240V 3Ø, plus 480V is one of the most dangerous voltages there is, if you eff up, your better off dead, so it should only be worked on by qualified people.

Hogwash.

This is a metal working shop, the load is there. 480v equipment is more available by far due to it being the defacto standard of common industrial equipment. Transformer losses are negligible. 120V can be just as bad as 480V installed wrong so it is really a moot point.

480 motors can be had cheap and are quite abundant. Metal working equipment like lathes, Mills, shapers, surface grinders and so on, standardly come in 480 form. That's a fact and not opinion.

 

[Bert_]

Hogwash.

This is a metal working shop, the load is there. 480v equipment is more available by far due to it being the defacto standard of common industrial equipment. Transformer losses are negligible. 120V can be just as bad as 480V installed wrong so it is really a moot point.

480 has way more arc flash potential than 120/240 ever will...
When stuff goes wrong on 480 is doesn't just throw a few sparks and trip the breaker, stuff can blow up.


480 motors can be had cheap and are quite abundant. Metal working equipment like lathes, Mills, shapers, surface grinders and so on, standardly come in 480 form. That's a fact and not opinion.

Have you even read the thread? OP has already told us that much of his equipment is 230V ONLY

I'm with the crowd of a 120/240V delta. You get three phase as well as 240V single phase, no transformers or multiple services. It is perfect for a small shop. I am not a fan of 208 wye for stuff like this, your line to neutral loads are minimal.

Do the load calc for sure but 200A goes a long way.

 

[Mr. T]

plus 480V is one of the most dangerous voltages there is, if you eff up, your better off dead, so it should only be worked on by qualified people.

Shouldn’t ALL electrical work be done by qualified people?

And I don’t take working on 480 lightly (I work on it often) but on a regular basis I fight against the notion of others that somehow 240 and 120 are “safe.” It seems like some people get a pucker in their ******** about 480 but then act like 240 is no big deal, and 120 can be done by children. Meanwhile I have the attitude that any of them will make you just as dead if you don’t understand what you’re doing and why you are doing it.

 

[DSMR]

I'm with the crowd of a 120/240V delta. You get three phase as well as 240V single phase, no transformers or multiple services. It is perfect for a small shop. I am not a fan of 208 wye for stuff like this, your line to neutral loads are minimal.

Do the load calc for sure but 200A goes a long way.

The design of the system dictates hazard mitigation. Your above argument is akin to saying a mustang with a v6 is safer than one with a V8.

I could think of a few reasons why an ungrounded Delta service would not be as desirable as wye (wye is now the most commonly used service and most new equipment defaults to wye configuration)

 

[alfredeneuman]

Shouldn’t ALL electrical work be done by qualified people?

The electrical section of this site solely exists for unqualified persons to ask DIY questions, and get answers from more qualified persons. Otherwise there would be no such section.
Most of the questions deal with voltages 240 and below, and it's perfectly safe to do the mechanical and even some of the electrical aspects with the power turned off if you ask the right questions, and if you don't ask the right questions there are plenty of qualified folks around to give a warning signal.

480 volts isn't a DIY voltage, and should be performed by professionals.

 

[DSMR]

The electrical section of this site solely exists for unqualified persons to ask DIY questions, and get answers from more qualified persons. Otherwise there would be no such section.
Most of the questions deal with voltages 240 and below, and it's perfectly safe to do the mechanical and even some of the electrical aspects with the power turned off if you ask the right questions, and if you don't ask the right questions there are plenty of qualified folks around to give a warning signal.

480 volts isn't a DIY voltage, and should be performed by professionals.

100mA can kill you. 120 volts is NOT ”DIY voltage”.

 

[Bert_]

100mA can kill you. 120 volts is NOT ”DIY voltage”.

Your not getting it, shock is only half the danger. With 480 even a 15A circuit has the potential to blow a cloud of molten metal in your face.

 

[Bert_]

I could think of a few reasons why an ungrounded Delta service would not be as desirable as wye (wye is now the most commonly used service and most new equipment defaults to wye configuration)

208/120 WYE is great for comercial stuff where you have lots of 120V lighting/ect. I do not like it for a site that is mostly line to line or motor load. For a small site with mostly motor load a 240V delta is great.

Not sure where ungrounded delta came up? We are talking about a delta with a grounded center tap. That's what gives us 120...

 

[DSMR]

Your not getting it, shock is only half the danger. With 480 even a 15A circuit has the potential to blow a cloud of molten metal in your face.

I am going to explain the same point again. All devices devices now have a SCCR rating (even 120/240 devices). The NEC states that you cannot supply a device with more fault current than it can handle. Therefore, if everything is to code, it should be perfectly safe with only a quite minimal risk of catastrophic failure. This risk can happen with 120/240/480/2300/69000. This magic threshold of unsafe voltage of anything over 480V is nonsensical.

In Europe their wall voltage is single phase 230.... Woooo they must be dropping from flies with all of that rogue unsafe diy voltage flying around zapping people all will nilly.

 

[alfredeneuman]

I am going to explain the same point again. All devices devices now have a SCCR rating (even 120/240 devices)

We are well aware of the Short Circuit Capacity Ratings.
They're in place to assure that the damaged component doesn't do damage upstream.
What's that got to do with it?

 

[wyliesdiesels]

This argument is silly.

480v is most definitely not a DIY voltage.

 

[wyliesdiesels]

The design of the system dictates hazard mitigation. Your above argument is akin to saying a mustang with a v6 is safer than one with a V8.

I could think of a few reasons why an ungrounded Delta service would not be as desirable as wye (wye is now the most commonly used service and most new equipment defaults to wye configuration)

Most if not all PoCos no longer allow or install new ungrounded delta.

If customer needs an ungrounded service for production reasons, it is done as a separately derived system on the load side of a grounded service.

 

[DSMR]

This argument is silly.

480v is most definitely not a DIY voltage.

DIY voltage is silly. This made up propaganda that 480vac 3 phase is some sort of dangerous voltage is poppycock. I argue if you are willing to look at 240V 3 phase then 480 should be looked at nearly the same. Most of North America industry lives on 480 for machinery.

In the grand scheme of things in the world of power, 120/240/480 is all considered low voltage. 1-35kV is medium voltage.

To each there own, but my opinion is if I was gonna put up a machine shop with 20 hp motors, 480 makes since. Power is cheap, equipment is cheap and easy to find.

 

[jeepxj]

DIY voltage is silly. This made up propaganda that 480vac 3 phase is some sort of dangerous voltage is poppycock. I argue if you are willing to look at 240V 3 phase then 480 should be looked at nearly the same. Most of North America industry lives on 480 for machinery.

In the grand scheme of things in the world of power, 120/240/480 is all considered low voltage. 1-35kV is medium voltage.

To each there own, but my opinion is if I was gonna put up a machine shop with 20 hp motors, 480 makes since. Power is cheap, equipment is cheap and easy to find.

uhhhh you sure?

Per IEEE 1584, Equipment below 240 V need not be considered unless it involves at least one 125 kVA or larger low-impedance transformer in its immediate power supply. This is about the incident energy exposure possible under these conditions during testing. It means no need to calculate incident energy on equipment under 240V fed from a transformer of size below 125 kVA, because the available fault current is not high enough to sustain an Arc-Flash and release significant energy.

480 is a big boy voltage to most.

 

[Bert_]

I am going to explain the same point again. All devices devices now have a SCCR rating (even 120/240 devices). The NEC states that you cannot supply a device with more fault current than it can handle. Therefore, if everything is to code, it should be perfectly safe with only a quite minimal risk of catastrophic failure. This risk can happen with 120/240/480/2300/69000. This magic threshold of unsafe voltage of anything over 480V is nonsensical.

In Europe their wall voltage is single phase 230.... Woooo they must be dropping from flies with all of that rogue unsafe diy voltage flying around zapping people all will nilly.

Does this DIYer's screw driver carry an SCCR? Cause that is what I would be worried about, or something similar. Guy does his own electrical, shuts of wrong breaker, forgets to check and has something blow up in his face when he puts the screw driver in there.

People modify equipment or use cheap parts. Read a few threads and I'm sure you'll find one asking about some cheap part from china.

People do dumb things when they don't know any better. A few months ago I went to work on a grain dryer. Had a reversing starter. The open contactor had welded closed and in an effort to close the electric gate the operator jammed a screw driver in the close contactor. The mechanical interlock must not have been very good because it went in and the whole mess blew up.

Much more forgiving on 120/240, probably walk away just needing a new screw driver instead of dealing with burns everywhere.

DIY voltage is silly. This made up propaganda that 480vac 3 phase is some sort of dangerous voltage is poppycock. I argue if you are willing to look at 240V 3 phase then 480 should be looked at nearly the same. Most of North America industry lives on 480 for machinery.

In the grand scheme of things in the world of power, 120/240/480 is all considered low voltage. 1-35kV is medium voltage.

To each there own, but my opinion is if I was gonna put up a machine shop with 20 hp motors, 480 makes since. Power is cheap, equipment is cheap and easy to find.

As the voltage level goes up so does the needed safety equipment.

Also not sure why your even arguing the point. you keep missing some fairly important info.

Only one machine I have is wired for 480. That would be the Gorton mill. The spindle motor can be rewired to 240 but there is some sort of rectifier for the power feeds and no idea what I'd have to change.

The older Cincinnati drill and the Lincoln welder are both 240 only. Only 3 motor leads.

The Lincoln uses a smaller circuit then my Miller Thunderbolt.

The plan for the compressor is to plumb it in with my 80 gallon CH and a 60 gallon tank. Only switch it on when needed. Otherwise run the 80 gallon on it's own.

If I ended up going the rotary phase converter path I'd probably build my own. Can get a used motor from work.

I'm done arguing anybody reading should understand the risks and can decide whether they have the skills and knowledge to work safely around 480V

 

[Mr. T]

To the OPs ask. If I were you, running what you talked about, I’d want the 480 service. It will give you a loooot more leeway to run bigger things and get used equipment at better prices. You’ll use the same type of wire and wiring methods, but it will be smaller wire (and conduit), making it cheaper.

That being said, I spose I’m what would be considered a “trained professional” qualified to work on such things. I feel that you need to understand and appreciate the danger in ALL electrical work but yes, 480 three phase has a higher potential for danger.

 

[alfredeneuman]

Back the OP's original question, I wired a metal building in the '80s of similar size, not as a machine shop but a welding shop with 6 employees.

They had a few 350 amp mig welders, numerous smaller welders, 2 Ironworkers, and a Blasting Cabinet with a 10 hp compressor, as well as lighting and many 120 and 208 general use receptacles for cutoff saws and the like.
I installed a 200 Amp 120/208 volt 3ØY service, all approved by the County during plan check.

They never had any problems with tripping breakers.

 

[jeepxj]

400 amps at 240v is 96kw of power draw. that is a lot of power to be pulling at the same time.

 

[sberry]

This is a 1 man show with a few small old machines. Its not unlimited budget and should be practical. I doubt that he is going to buy new 50 hp water jet. While some old stuff is cheap there are some netter ways to do some stuff. Rig or serve for a few modest used items, get a modest compressor. Is the welder and tje like a real deal,,, sort of but the tbolt can do the same work for most people not in the full time welding business. Not that it cant be used but ****, its a great way to outfit an ironwork gang in factory repair but I dont want it. Rather have a 150 Maxstar for real day to day work unless I was rebuilding heavy excavating equipment and even then there may be other economic factors.

 

[sberry]

400 amps at 240v is 96kw of power draw. that is a lot of power to be pulling at the same time.

How many $ an hour is this?