Question about voltage drop

[Ran58]

I am building a workshop located about 350 ft from house. House has 320 amp service. I already have a 100 amp wire run from house to barn (about 280 ft) that is used to power a well that I use to irrigate my grass primarily.

Asked my electrician if I could run a wire from barn to new shop ( about 70 more ft) to provide power or would I need to run a new line from power pole located about 40 ft from new shop. This would require a new meter along with a base service charge of $32 per month even if I don’t use any electricity during the month. Electrician said he wouldn’t worry about running power from barn for lights but would be concerned about running air compressor, welding machine, because potential voltage drop could damage the equipment. Note that I do not anticipate that I would be running the well and air compressor at the same time nor the air compressor and welder at the same time, etc.

Question is this - Is there any way to determine or measure what the voltage drop would be so that I could determine if The voltage drop would be a problem. Thanks

 

[garfunkle24]

Depends what wire you ran to the barn and will run to the shop.

Voltage drop calculator

 

[theoldwizard1]

Not enough information !

What size is the current wire to the barn ? What size is the breaker in he house
Besides the irrigation pump (1hp, 5hp ?) what other loads are in the barn (ignore lights) ?

Most one man shops can run easily on a 60A circuit. If you are running a plasma cutter (which requires shop air) you might have to shut off the A/C in the shop.

Modern power equipment is more tolerant of low voltage, some A/C units will run on 208-240VAC.

 

[fitter30]

Max voltage drop 3%

 

[acer66]

Maybe ask here.

Lighting & Electrical

Don't SHOCK yourself...

www.garagejournal.com

 

[jimj580]

Maybe ask here.

Lighting & Electrical

Don't SHOCK yourself...

www.garagejournal.com

Find an online voltage drop calculator
You will need to load in amps, wire size and distance

 

[CraigStu]

I am glad to see you are asking about this. It's apples and oranges but decades ago I burned up the motor in my Craftsman radial arm saw. Took it to a motor repair guy. He started disassembling it and about 2 minutes in says can I ask you a question? Sure. Have you been running this on an extension cord? Uh, yeah sometimes. Get a much heavier cord or you will be back here in 6 months.

 

[wyliesdiesels]

Max voltage drop 3%

Not true.

There is no MAX limit in code. Because voltage drop is a design issue not a safety one.

3% is suggested for feeders and 5% is suggested for branch circuits.

 

[wyliesdiesels]

I am building a workshop located about 350 ft from house. House has 320 amp service. I already have a 100 amp wire run from house to barn (about 280 ft) that is used to power a well that I use to irrigate my grass primarily.

Asked my electrician if I could run a wire from barn to new shop ( about 70 more ft) to provide power or would I need to run a new line from power pole located about 40 ft from new shop. This would require a new meter along with a base service charge of $32 per month even if I don’t use any electricity during the month. Electrician said he wouldn’t worry about running power from barn for lights but would be concerned about running air compressor, welding machine, because potential voltage drop could damage the equipment. Note that I do not anticipate that I would be running the well and air compressor at the same time nor the air compressor and welder at the same time, etc.

Question is this - Is there any way to determine or measure what the voltage drop would be so that I could determine if The voltage drop would be a problem. Thanks

As other shave stated, we need more info here

If you have the existing wire size, you can calc the VD at a given load, by hand with the formulas i posted in the FAQ sticky

 

[fitter30]

Not true.

There is no MAX limit in code. Because voltage drop is a design issue not a safety one.

3% is suggested for feeders and 5% is suggested for branch circuits.

Guess u do don't think barn to shop isn't a feeder.

 

[alfredeneuman]

Guess u do don't think barn to shop isn't a feeder.

Guess u don't understand the meaning of the word suggested
If it was mandatory it would say so.

 

[exranger06]

You can plug a bunch of appliances/devices into the barn and turn all of them on so that you're drawing 90-100A through the feeder. Then measure the voltage at the barn's panel to see what the "worst case scenario" voltage drop is. Then see how much more voltage drop would be tolerable, if any, at the new shop. Size the wire accordingly.

 

[fitter30]

Guess u don't understand the meaning of the word suggested
If it was mandatory it would say so.

Just because u can doesn't mean u should. Since low voltage kills inductive and electronic loads far more why would anybody design a underrated wiring system with low voltage. With the tools today almost everyone of them incorporate electronics.

 

[mike93lx]

Guess u do don't think barn to shop isn't a feeder.

Read your post again. You are aren't clear on what you did didn't try to convey

 

[wyliesdiesels]

Guess u do don't think barn to shop isn't a feeder.

try reading the code again. you claimed it was MAX. this is false. the 3% is SUGGESTED.... try again

 

[wyliesdiesels]

Just because u can doesn't mean u should. Since low voltage kills inductive and electronic loads far more why would anybody design a underrated wiring system with low voltage. With the tools today almost everyone of them incorporate electronics.

tell me youve never opened a code book without telling me youve never opened a code book

 

[fitter30]

tell me youve never opened a code book without telling me youve never opened a code book.

Never have just call a local 1 wire person and tell them what i need done. Being a service fitter working on industrial and commercial chillers, boilers and controls.