Another Sub-Panel Question

[Mike Ruggeri]

As there have been several questions on sub-panels recently and sizing requirements, I thought I would go ahead and ask my questions as I am soon going to put a sub-panel in my shop/garage.

Background: My shop is in my garage - attached to the house about 50+ feet from the main panel (complete opposite sides of the basement). The most I could see running at the same time would be a 5hp machine (my current largest is 3hp but I have a jointer/planer combo on my wish list that would probably be 5hp) and my 1 1/2hp dust collector. Lights will not be run through the sub-panel and if I get a big compressor someday, I could wire it to an existing 30amp supply (for a dryer that is no longer required since we switch from electric to gas). For the actual panel, I will probably get one with 20 or so slots to allow for extra capacity (but right now I anticipate having 2 110 20 amp, 1 240 20 amp, 1 240 15 amp). I am going to run all the wires and do the grunt work and then have an electrician friend do the actual hook-ups.

Questions: I would think 50 amps should be fine for my needs, but would welcome the thoughts of others. If I go 50 amps, I was thinking 6/3 copper NM as it would relatively easy to run across the basement. The other alternative would be 2/3 aluminum SER which would probably be a little cheaper. Any preferences on the wire choice? As the largest wire I've worked with so far is 10 gauge, not sure if the 2 SER would be much more difficult to run vs the 6 NM. Lastly, if I go with 50 amps, do I have extra capacity to run some lights off of the subpanel (I will also have the existing lights that are supplied from the main panel)?

Thanks in advance for your input.

Mike

[Rod Sheridan]

Hi Mike, I wouldn't use aluminum wire personally. The trick is joint preparation, and routine inspection, the cost savings for a small job at home isn't worth it to me.

50 Amperes is a lot for a single phase 5HP motor and a 1.5HP motor.

I have a 1.5HP Oneida cyclone and the remainder of my machinery is 3HP with the exception of a 4HP jointer/planer.

The 3HP motors are 12.5A full load, the planer/jointer is limited to a 16A feeder, so I use 15A feeders for all the machinery.

Runs just fine off a 30A feeder to my shop subpanel, you would certainly have room to spare with a 50A feeder for your panel.

Home shop equipment rarely runs at max load, and if it does, it's of a very intermittent nature.

Regards, Rod.

[Michael Sobik]

I was set on a 100 amp panel, but my dad talked me into a 50 amp saying it would be more than enough. As usual, he was right. I can run a large window AC unit, my Grizzly 3hp cyclone, my pancake compressor, and any of my other machines (BS, planer, or jointer) with no problems. For one person, I think 50 amps is plenty.

[Von Bickley]

I would think 50 amps should be fine for my needs, but would welcome the thoughts of others. If I go 50 amps, I was thinking 6/3 copper NM as it would relatively easy to run across the basement.

The 6/3 copper with ground would be a good choice. That is what I would do. (Retired Electrician)..........

[Mike Ruggeri]

Rod - What you have is close to what I currently have (I also have the 1.5hp Oneida DC + other 3hp machines), but you have the jointer/planer too (hopefully I will be lucky enough at some point in the future to upgrade although I don't see this happening in the short term unless I can find a used machine at a good price). I think 50 amps should be fine but I always value the views of others on this forum as other usually have more knowledge than I do. Also, I agree the cost differential is small between copper and aluminum so that is why I was leaning towards going with the copper if it would provide enough juice.

Michael & Von - Thanks for the input. I'm glad you agree 50 amps should be fine as I think 6/3 should be pretty easy to run betwen the main panel and sub-panel.

Mike

[Jimmy Coull]

I ran a 60 amp service to an old detached shop that I had and used 6/3 w/g wire and had absolutely no problem. My wire was free and someone gave me the subpanel and that is why I did it that way. I probably would have gone with a hundred amp panel and matching wire if I had to pay for it. The extra cost of the raw material was not that big of a difference in the total cost. I am now in a larger shop (32 x 40 over 18 x 36) and have larger equiptment and at any one time I have a 3hp TS or planer, 3hp cyclone, 5hp. air compressor, and a bank of 15 sets of 4' fluorescent lights going and I don't think that the 60 amp service would have handle it.

So all I'm asking is how much more overall is it going to cost to got to a 100 amp service, also for a few dollars more I'd go foral panel with more than 20 spaces. 220 breakers should be dedicated to most equiptment and they take up 2 spaces, the eat up panel spots quickly.

JMTCW.

Good Luck,
Jimmy

[John Morrison60]

Mike

I would think that 50 amps is plenty.
You can put multiple 220 outlets on a single circuit. Just pick two pieces of
equipment that you would not run simultaneously. (assuming you are a one man shop). I run a single 220 and a single 20 amp 110 for my shop. The only equipment
that is isolated is the cyclone.

Aluminum wire is fine for the run from the main. It is cheaper, lighter, and more flexible. Go up one guage to 6 and you will carry 50 amps fine.
The knock on aluminum is that it can loosen up at connections over time, especially if the connections are not rated for aluminum.
All panel connections are rated for aluminum and they are easy to see and fix anyway.
You can bet that the power company ran aluminum to supply your house.

Good luck
John