RESIDENTIAL OR COMMERCIAL

[Keldra]

ESTIMATING A METAL BUILDING THAT IS GOING TOO BE USED AS A SMALL MACHINE SHOP ,APROX- 20X30 FT ON A RESIDENTIAL PROPERTY FEED FROM THE MAIN PANEL 225 AMP ON THE RESIDENCE I AM TRYING TO DETERMINE WEATHER IT WILL BE CONSIDERED RESIDENTIAL OR COMMERCIAL AS THE NEC APPLIES, ANY OPINIONS - TEXAS. THX.

 

[jumper]

It really comes down to what shop will be zoned as.

Please do not type in all caps, it can be considered rude and makes for hard reading.

 

[Keldra]

ZONING

ZONING

Would think residential since no seperate address , and fed from main panel on residence

 

[jumper]

Would think residential since no seperate address , and fed from main panel on residence

The load calc. will be so similar that the difference would probably rather negligle.

Except whether the lighting is continuous or not and general recs. at 180VA-the real load will be the machinery.

Is it a shop with more than one person as in many of the machines all being on at once?

3 guys 8 hours a day pulling 40 hours or a one man band after hours and weekends?

A 20x30 shop does not sound like a big shop.

 

[Keldra]

Use of shop

Use of shop

1 to 2 guys ,hours will vary per day, probably not all equip running at once.

 

[jumper]

1 to 2 guys ,hours will vary per day, probably not all equip running at once.

While I usually apply this to HVAC, it is a factor. 2 guys cannot run 3 welders, lathes, drill presses, etc.

220.60 Noncoincident Loads. Where it is unlikely that
two or more noncoincident loads will be in use simultaneously,
it shall be permissible to use only the largest
load(s) that will be used at one time for calculating the total
load of a feeder or service.

I would probably size the feeder to the 3 largest machines + anything like drying ovens that run unmanned + appliances like a fridge, coffeemaker, micro and such + lighting at 100%. Take total and add in a fudge factor of at least 10% (prefer 20%) for expansion later and unknown loads such as chargers and what not.

 

[jiggawatt79]

this may be a generic answer but I usually find out the inspector that will be involved on the project and ask him direct. This way there are no surprises.

 

[jumper]

this may be a generic answer but I usually find out the inspector that will be involved on the project and ask him direct. This way there are no surprises.

Not generic at all, as I said in post #2, how the AHJ zones it is the deciding factor.

 

[renosteinke]

This thread is a real land mine as far as codes are concerned. You will definitely have to work closely with your AHJ on this one.

Right off the top, I see two big problems.

The first is the power. Once you get past 1-1/2hp, it gets a lot harder to find and a lot more expensive to purchase machinery. Since the typical "Bridgeport" mill and 'engine lathe' are usually 2hp, I expect you will really want to have three-phase power available. Only the PoCo can help you there.

The other 'red flag' is plumbing. If you're going to have a sewer hook-up (say, for a toilet) the AHJ is going to consider whether this might become a 'granny flat' in a few years.

 

[petersonra]

This thread is a real land mine as far as codes are concerned. You will definitely have to work closely with your AHJ on this one.

Right off the top, I see two big problems.

The first is the power. Once you get past 1-1/2hp, it gets a lot harder to find and a lot more expensive to purchase machinery. Since the typical "Bridgeport" mill and 'engine lathe' are usually 2hp, I expect you will really want to have three-phase power available. Only the PoCo can help you there.

The other 'red flag' is plumbing. If you're going to have a sewer hook-up (say, for a toilet) the AHJ is going to consider whether this might become a 'granny flat' in a few years.

Why would the AHJ give a rat's behind about what the property might be used for at some point in the future? And on what basis would they have to do that? In any case, how is plumbing related to the electrical work the op is asking about?

To answer your question it is residential. It does not matter what is actually in the structure as long as it is not a business.

As for the motor voltage, it may well be cheaper to replace the 3 phase motors that often come with machine shop equipment with single phase motors than to change to a 3 phase service.

Incidentally, it is probably better for the owner not to refer to it as a machine shop in any official documents. garage or storage building is a better choice.

 

[petersonra]

I forgot to add. You might also be able to use VFDs that take single phase in and give you 3 phase out for the motors.

 

[renosteinke]

Well, Bob, while I appreciate your passion ....

I've been involved in several such workshop conversions where the city building department most certainly did give a 'rats ass' about what they speculated might be a future use. The net result was: add plumbing and the permit is denied. Thus began the long appeals process, etc.

Mind you, that 'biggest little' city has also, in the past, taken the position that you absolutely had to be zoned for 'commercial' if you ran a business from your house. They even tried enforcing it against a free-lance writer and a rather noted author of novels; both persons had the foolishness to admit that they wrote from their 'home offices.' It was necessary to ammend the city code to rein in this silliness.

Likewise, the town next door has a gunsmith of some repute, with quite the shop in his attached garage. Over the years he has had to deal with all manner of problems stemming from the zoning prohibition of 3-phase services in residential areas. PLC's and phase converters get cumbersome after a while.

A lot of older commercial equipment is showing up in the auction markets, and I've met meny - one on this very forum- who have faced difficulty with the lack of three phase power to thier garage-shops.

 

[petersonra]

Well, Bob, while I appreciate your passion ....

I've been involved in several such workshop conversions where the city building department most certainly did give a 'rats ass' about what they speculated might be a future use. The net result was: add plumbing and the permit is denied. Thus began the long appeals process, etc.

Mind you, that 'biggest little' city has also, in the past, taken the position that you absolutely had to be zoned for 'commercial' if you ran a business from your house. They even tried enforcing it against a free-lance writer and a rather noted author of novels; both persons had the foolishness to admit that they wrote from their 'home offices.' It was necessary to ammend the city code to rein in this silliness.

Likewise, the town next door has a gunsmith of some repute, with quite the shop in his attached garage. Over the years he has had to deal with all manner of problems stemming from the zoning prohibition of 3-phase services in residential areas. PLC's and phase converters get cumbersome after a while.

A lot of older commercial equipment is showing up in the auction markets, and I've met meny - one on this very forum- who have faced difficulty with the lack of three phase power to thier garage-shops.

I don't have a problem with them requiring commercial zoning if it really is a business. that is why I suggested not calling it a machine shop. garage sounds a lot less like it might relaly be a business.

If the city wrote the code so expansively that it included free lance writers as commerical, it sounds like the inspector was just following the rules. Perhaps a bit more zealously then one would hope.

People around here get nailed pretty regularly when they want to have a business on their residential property. Its a pretty common thing. I even recall there was a chiropractor that had an office in his basement. Hair stylists used to be common on people's front porches, although you do not see many of them that way anymore. I suspect ADA issues make that very hard these days, although supposedly for very small businesses there is some kind of exemption. It is usually not all that hard to get a zoning variance for a home business around here, but you do have to go thru the steps to get it, and it can take 3-4 months. biggest issue is usually parking.

I can honestly say I have never heard of a permit being turned down over fears someone might change the use of the facility in the future.

I will say it is not all that easy around here to get a permit to put a toilet into a garage or a similar structure. They are afraid you will contaminate the city sewer.