# Load Calculations Machinery



## dronai (Apr 11, 2011)

Have a customer, who is leaving a shared machine and sheet metal manufacturing shop, and is looking for his own 5000sq-6000sq space.

I'm seeing if he should *not* consider the 200A 240V 3 phase buildings

He only has one 480V machine, the rest are 240V 3 phase, and about 15 are about 2hp or less. Another 15 are less than 1hp 

The load comes out to 128,000VA / (240*1.73) = 310A

He figures the machines are used 25% of the time, but with a bigger place, he may use more manpower, and get up to 50%

Looks to me like it's safer to have him look at 400A @ 240V service only. Any other input would be appreciated


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## gpop (May 14, 2018)

Any heating, cooling, water heater, welding, etc


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## VELOCI3 (Aug 15, 2019)

What is available in the area he would move to should be considered first. Then you can be paid to survey the power suitability at each site which would include existing conditions, cost to retrofit, ability to scale up. 


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## dronai (Apr 11, 2011)

gpop said:


> Any heating, cooling, water heater, welding, etc


Yep, got all those in there except the waterheater D'uh !!! Welding outlets he didn't request, but that's another good one


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## Forge Boyz (Nov 7, 2014)

Just do I understand, you are talking about an existing building with the service already there, not putting a service in, correct

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## dronai (Apr 11, 2011)

VELOCI3 said:


> What is available in the area he would move to should be considered first. Then you can be paid to survey the power suitability at each site which would include existing conditions, cost to retrofit, ability to scale up.
> 
> 
> Sent from my iPhone using Tapatalk


480V 3 phase is more expensive, and in his case not required.

200A/240V is cheaper than 400A/240V, that's why he hired me to go take a look at his machines, and calculate it for him.

With how many machines I saw unmaned, I'm thinking his demand is pretty low, but I stuck in the numbers at 100% including AC, general lighting, general receptacles.

He doesn't need me to go look at each, if he knows the minimum he needs


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## dronai (Apr 11, 2011)

Forge Boyz said:


> Just do I understand, you are talking about an existing building with the service already there, not putting a service in, correct
> 
> Sent from my SM-G970U1 using Tapatalk


Yeah existing, he's shopping for a new building


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## Forge Boyz (Nov 7, 2014)

Yeah after I reread your original post I saw you had pretty much said that. Do you have a lot of delta services or are they usually 120/208?

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## dronai (Apr 11, 2011)

Forge Boyz said:


> Yeah after I reread your original post I saw you had pretty much said that. Do you have a lot of delta services or are they usually 120/208?
> 
> Sent from my SM-G970U1 using Tapatalk


Yes Delta. Most older Industrial buildings I work at are 240V or 460V the 208V or 480V I see are in newer commercial/industrail space.

You think 200A /240V is too little ?


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## VELOCI3 (Aug 15, 2019)

dronai said:


> 480V 3 phase is more expensive, and in his case not required.
> 
> 
> 
> ...




I would think that there would be so many other criteria in moving a business like this. 

Location, accessibility, parking, loading dock, freight elevator etc. 

Adapting the space for his power requirements would be something that you could do.

This reminds me of jobs with supers that were previously in a trade. They focus on what they know and neglect the big picture. 


Not that you are doing this but power can and will need to be upgraded or retrofitted at any location he chooses. Those other criteria might be more difficult and expensive to accommodate in relation to an electric upgrade. 


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## dronai (Apr 11, 2011)

VELOCI3 said:


> I would think that there would be so many other criteria in moving a business like this.
> 
> Location, accessibility, parking, loading dock, freight elevator etc.
> 
> ...


Good points ! I'm sure their group is evaluating most. This is a pretty small operation, the guy he shares the space with, just landed a big contract, and is being squeezed in his space now.


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## Forge Boyz (Nov 7, 2014)

dronai said:


> Yes Delta. Most older Industrial buildings I work at are 240V or 460V the 208V or 480V I see are in newer commercial/industrail space.
> 
> 
> 
> You think 200A /240V is too little ?


What HP are his bigger machines? We replaced the panel in a machine shop last summer where the guy had a bunch of lathes but didn't run very many. His biggest load is a parts washer that has around 27kw of electric heat for the water. His air compressor is a 20HP I believe. It's all running off a 200A 240V 3ph service and he doesn't seem to have problems. We did put a 400A panel in incase he ever needs to upgrade. 
Your customer very likely could run off a 200A service but I don't think I would recommend it. He wouldn't have a lot of capacity to expand, and as he adds more workers load will go up of course. 

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## dronai (Apr 11, 2011)

Forge Boyz said:


> What HP are his bigger machines? We replaced the panel in a machine shop last summer where the guy had a bunch of lathes but didn't run very many. His biggest load is a parts washer that has around 27kw of electric heat for the water. His air compressor is a 20HP I believe. It's all running off a 200A 240V 3ph service and he doesn't seem to have problems. We did put a 400A panel in incase he ever needs to upgrade.
> Your customer very likely could run off a 200A service but I don't think I would recommend it. He wouldn't have a lot of capacity to expand, and as he adds more workers load will go up of course.
> 
> Sent from my SM-G970U1 using Tapatalk


The 480V machine was around 10HP, if he adds a large compressor, I'm thinking those are about 10HP. Most everything else is about 2hp, and about 15 are 1/2hp or 1hp machines.


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## Forge Boyz (Nov 7, 2014)

How many machines total?

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## dronai (Apr 11, 2011)

Forge Boyz said:


> How many machines total?
> 
> Sent from my SM-G970U1 using Tapatalk


just over 30


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## Forge Boyz (Nov 7, 2014)

Do you know total HP?

ETA looks to be about 60?

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## dronai (Apr 11, 2011)

Forge Boyz said:


> Do you know total HP?
> 
> ETA looks to be about 60?
> 
> Sent from my SM-G970U1 using Tapatalk


No, I couldn't read a lot of the nameplates. The bigger machines, some were 2 hp, so I used that for all of those. All #12 so cord connected. You could be right on the total hp.

Then you have all of the loads for the building to function


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## Forge Boyz (Nov 7, 2014)

How many of the machines will run at the same time? Or is that an unknown that will be based on how many people are working there?

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## dronai (Apr 11, 2011)

Forge Boyz said:


> How many of the machines will run at the same time? Or is that an unknown that will be based on how many people are working there?
> 
> Sent from my SM-G970U1 using Tapatalk


25% maybe If he grows, possibly 50%


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## CMP (Oct 30, 2019)

What I would suggest is to go measure his actual loads while its still connected, and have him put a working load on each one, to get an actual number. Its common for small industrial equipment to not draw anywhere near the nameplate, in normal use.


As an example, one customer wanted to add a 100HP bridge mill, to a shop with several other loads. The machine specifications called for a 300A 480V ckt. That load was a bit large for the existing service and load. But to come up with a real load number, we went to another shop of his, with a similar large mill and did a test. With their biggest and dullest cutter, that they run, on the worst alloy log that they process. 

Turns out that the load never exceeded 125A, and he got his new mill and it ran fine, along with the other loads, protected by a fused switch 200A switch with 150A fuses.


You are likely to find something similar if you make the time to test, before disconnection.


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## splatz (May 23, 2015)

Load calculations are a form of fortune telling, machine shops are very tough to predict. 

I would not disregard the customer's 25% and 50% estimates but I would throw out the numbers (which he just pulled out of his ass) and only look at the gist of it - he doesn't use much of his equipment simultaneously now, but he might use twice as much electricity if he gets twice as much space. 

The machine shops I have dealt with occasionally get a big rush job or a deadline and they'll be using much more than usual, this is very hard to predict. Those are not situations where they can just turn off a couple machines, slow down and relax if they find out their service is undersized.

They'll also out of the blue buy a big machine that dramatically increases their load. There is a big secondary market, they might get something at auction they can't pass up that will open up new work for them. Or say they buy a waterjet, or buy a bigger waterjet. Some of those are 200hp. One local guy, rumor is he got a single contract that would basically pay for his waterjet. 

Having the electrical capacity doesn't cost that much and when you look at it as opening up additional business opportunities it's well worth it. Go heavy.


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## CoolWill (Jan 5, 2019)

Depending on the rent, a 30 amp 120 V circuit might be good enough.


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## dronai (Apr 11, 2011)

splatz said:


> Load calculations are a form of fortune telling, machine shops are very tough to predict.
> 
> I would not disregard the customer's 25% and 50% estimates but I would throw out the numbers (which he just pulled out of his ass) and only look at the gist of it - he doesn't use much of his equipment simultaneously now, but he might use twice as much electricity if he gets twice as much space.
> 
> ...


Talked with the guy yesterday, he is going to oversize for this reason.


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## JRaef (Mar 23, 2009)

Here's how I would approach it:


If he moves into a building with more space and his business grows, 200A 240V may max out faster than he thinks, at which time trying to change to 400A will cost him a lot. If he gets a 400A service drop and doesn't use it for a few years, all he is out is the slightly higher cost of the 400A panel. The service cost shouldn't be any different, it's still only going to be based on his actual usage.


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## dronai (Apr 11, 2011)

JRaef said:


> Here's how I would approach it:
> 
> 
> If he moves into a building with more space and his business grows, 200A 240V may max out faster than he thinks, at which time trying to change to 400A will cost him a lot. If he gets a 400A service drop and doesn't use it for a few years, all he is out is the slightly higher cost of the 400A panel. The service cost shouldn't be any different, it's still only going to be based on his actual usage.


I think from what I understand, the commercial/industrail realtors say, the cost per sq ft is a little more for more available power. But I agree with you


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