Enough amps?

Rennie Heuer

Moderator
Staff member
Messages
11,607
Location
Constantine, MI
Our new home has 100 amp service to the house. Currently there is a 60 amp 240 V line running to a subpanel in the garage. I had toyed with the idea of bringing a new service for the shop but in an effort to save a few dollars I am wondering if the 60 amp feed to the subpanel in the garage will be sufficient. Remember it is a one-man shop and I'm likely never to run more than just a dust collector and one PowerTool at a time. What say you?
 
Our new home has 100 amp service to the house. Currently there is a 60 amp 240 V line running to a subpanel in the garage. I had toyed with the idea of bringing a new service for the shop but in an effort to save a few dollars I am wondering if the 60 amp feed to the subpanel in the garage will be sufficient. Remember it is a one-man shop and I'm likely never to run more than just a dust collector and one PowerTool at a time. What say you?

Need a bit more info.
How big are the Tablesaw, Bandsaw, and Dust Collector? A 3hp saw and a 3hp DC will pretty much eat up your available power, but smaller units will likely be okay.

Don't forget, you'll need a 20 amp circuit for lights - and what about heat?

Running an AC in the hot months?

Outlets for sanders, etc. - another 20 amp circuit.

Do you have a compressor? How big?
 
When I built an addition to the existing shop at our place in Georgia, I had it provisioned for 100A service with a line from the existing 200A service to the house. If I add up everything I could possibly have on at the same time, it might be near 60A. That includes table saw(3hp), dust collector (3hp), compressor (5hp) kicking on, AC (10,000btu) on, as well as lights, PC, etc. I've never done a current measurement to get real-world usage but I'm sure it's less than calculated.
 
I needed to hop out for a minute to check a couple of things. My shop panel has 32 breaker positions with a total of 480A of breakers - on a 100A service. I broke the shop down to many seperate circuits.

From the Engineering Toolbox website:
As a "rules of thumb" amps horsepower rating can be estimated to
115 Volts motor - single-phase : 14 amps/hp
230 Volts motor - single-phase : 7 amps/hp


Add up what you'll be using and see what your total is.
 
I may need to go back to school on this one. Actually there are 2 30 amp breaker's linked together supplying the subpanel in the garage. So, I think I may have misspoken and the supply to the garage is 240 V @ 30 amp's. Would that be correct?
 
Jim pretty much asked everything, but keep in mind that LED Lighting is getting a whole lot less expensive and better looking/natural shades of light, so that 20 amps could be cut down to just a few amps. Electric heat would be a big draw, but a pellet stove could run off just a few amps, or just take it out of cycle when running the large machines.
 
I may need to go back to school on this one. Actually there are 2 30 amp breaker's linked together supplying the subpanel in the garage. So, I think I may have misspoken and the supply to the garage is 240 V @ 30 amp's. Would that be correct?

I believe a picture is in order ;)

My guess is you have one 30a 240v circuit.

A short enumeration of your heaviest draw machines would also be handy to figure if you're close or not.
 
Sure sounds like you have 30 amps at the moment. The last 2 shops I had each had 100 amp subpanels, though a lot of folks recommended 60 would be more than plenty. If you have very large tools (5 HP saw, DC, etc.) you may exceed the 60 amp service, but then again you might not.
 
Looks like the short answer to enough amps is no. And sufficient power is one are I personally would not want to save pennies in this area. Putting in a 100 amp box when initially building is ever so much cheaper than burning the place down or redoing the panel later.

My little 700 sqft house will have a 200 amp panel and sufficient lights and outlets everywhere. As the years go by more technology comes along and all of it seems to want an outlet!

Sometimes it is wiser to bite the bullet and then happily move on. You will mot regret it and you will sleep better at night.
 
Our old 100 amp panel was stuffed to the gills with double breakers. Upgrading it to a 200amp panel and running the sub panels was a little pricey but well worth every penny.

Not to mention having the generator sub panel connected.

The inspector referred to the old panel as the 'house burner' model.

As Carol said, I do sleep better at night having done the upgrades.
 
Yep, gonna have to figure into the budget bringing new service in from the street with a separate meter for the shop. Alternately, upgrading service to the house and pulling new wire to a sub panel in the shop.
 
Another thought: I wish I had had the electrician install two breaker boxes in my shop rather than just one big one. That way, I could have had one box with all the big tools in it and a main breaker to disable them.
 
Yep, gonna have to figure into the budget bringing new service in from the street with a separate meter for the shop. Alternately, upgrading service to the house and pulling new wire to a sub panel in the shop.

When we were getting our panel redone, I asked the guy about redoing the main service wire. Currently it's an above ground line running from the pole to the roof. Got some trees around it and wanted to know if it would be worth it to get it buried.

He indicated that would be a pretty major expense and not worth it.

How old is your house and what does the current box look like?

Here is my Before and After
MainPanel Before.jpgMainPanel After.jpg
 
Yep, gonna have to figure into the budget bringing new service in from the street with a separate meter for the shop. Alternately, upgrading service to the house and pulling new wire to a sub panel in the shop.

Check to see if your insurance will give a discount for an upgraded panel too, they usually do, might help offset some costs.
 
Yep, gonna have to figure into the budget bringing new service in from the street with a separate meter for the shop. Alternately, upgrading service to the house and pulling new wire to a sub panel in the shop.

Double check on the pricing of a separate meter; around here there would be an extra service charge of about $25-30/mo which can make upgrading the old panel look a bit more attractive in the longer run.
 
Top