Reply by JBrow

  • Advertise with us

Posted on Garage Workshop Settup

View JBrow's profile


1368 posts in 1801 days

#1 posted 07-25-2017 05:44 PM


Sorry for the long post, but then you asked a lot of questions and I tried to address each one.

Since you will have an electrician install your circuits and wish to avoid future visits from the electrician as the shop grows, it seems to me that a shop layout plan would be an extremely helpful first step in answering your questions. Ideally the shop layout would be drawn to scale. Once the shop layout sketch is developed, locations for the placement of the various machines would be known.

Determining the power requirements for the machines you now have and for the machines you plan to acquire would be helpful. For example, planers range widely in power requirements from 120V 15A to 240V 30A (5 hp). With the machines located and their power requirements known, locating and specifying power requirements would be straightforward.

The posted layout plan for a 2 car garage (with no provision for a car) shows placement of the tools, the power requirements for each tool, and the approximate location of the 240V and 120V receptacles. The single 240V 30A receptacle shown between the planer and table saw services the table saw, surface planer, bandsaw, and drum sander. It is a one-person shop and therefore only one machine is ever operated on this one circuit. The remaining 240V receptacles are dedicated circuits. The mortiser is on the only dedicated 120V circuit. Hopefully the sketch is helpful.

- how many 220v outlets would make sense for my situation?
For one trip of the electrician; the answer seems to depend on the power requirements of the tools you now have and expect to acquire in the future and whether more than one tool will operate on a single circuit at the same time. In my shop, I get by with five 240V outlets, but four machines operate on the same circuit in my one-person shop. Since the dust collector operates while another machine is in use, ensuring the dust collector is on a dedicated circuit makes sense to me.

You could load up the shop with dedicated circuits but I suspect that will add a fair amount to the cost of completing the electrical work.

- would you use 10/2 wire to run the 220v outlets or 12/2?
Running 10-2 cable rather than 12-2 would support a typical 5 hp motor. But 10-2 cable will cost almost twice that of 12-2 cable. But as Jonah commented, it is difficult cable to run and connect. That could possibly translate to a higher labor cost.

I ran circuits that are sized to meet the requirements of the machine/circuit, but then I did all the electrical work as I received a new machine.

- what is commonly needed for the AC/heat mini-split units?
Since I know little about HVAC equipment, I am unable to answer the question definitively. But my understanding is that the mini-split systems tend to be heat pumps and operate similar to air conditioning. If correct then as a rough guess 240V 30A may be the power requirement (based on the power required by my A/C compression). But then if you ultimately require a 240V 50A circuit and only ran 10 gauge copper to the mini-split location, the electrician will have to return. If the mini-split uses electronics and/or operates a blower motor at 120V, the power requirement may be two line conductors, a neutral conductor, and an equipment grounding conductor (for example 10-3 w/ ground rather than 10-2 w/ground).

Therefore, it may be worthwhile to discuss the heating and cooling requirements for the garage with an HVAC contractor. They should be about to perform a load calculation based on the size of the garage, number of windows, and on the insulation. From the load calculation, the proper size of the unit and its power requirements can be found.

In my case, I sweat in the summer but stay comfortable in the winter with three 1000 watt Infrared lamps installed on the ceiling.

- do the 220v outlets each need their own breaker? (I assume so.) If so, 30 amp?
Obviously a dedicated circuit would require its own breaker. I am not certain whether it is safe (for person and/or equipment) to operate a 15A tool on a 30A circuit. Therefore, I try to match the circuit size to the power requirements stated by the machine’s manufacturer.

- if I do the ceiling outlets, what type of retractable outlet/cord should I get?
Several 240V 30A circuits are ceiling-mounted in my shop. The receptacle matches the NEMA L14-30P configuration and is a locking plug (twist the plug and it locks into the receptacle).

I have few 120V ceiling mounted receptacles. They seem to hold the plug well enough, but a locking plug and corresponding receptacle could be used. Here is a NEMA configuration chart.

I have used rubber jacketed stranded copper Type SJOOW power cord to connect machines to receptacles. I found it at Lowe’s in various sizes sold by the foot.

- would you use 10/2 or 12/2 to run underground to the shed when it is built?
Running the largest cable you can afford would maximize the power available in the shed while reducing voltage drop across the distance from the subpanel to the shed. Since trenching and laying new cable is laborious, expensive, and tears up the yard, I believe paying extra for the larger sized wire makes sense when first wiring the shed.

- anything else that I’m forgetting?
At this point in preparing the 2 car garage as a workshop, there is a good chance that there may be unforeseen electrical requirements at some time in the future. Therefore, considering how any new circuits would be run could save time and money down the road. Anything done now to make getting an electrical cable from the subpanel to a new power-requiring location could make any future electrical upgrades easier.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics