Tuesday, August 2, 2016

Safe Motor Testing Gear


If you have occasion at times to bench-test fractional horsepower motors, you may find these items helpful. I wouldn't be without them.

First off is a switched outlet box with its own line cord attached. Here's a view of the one I made up for my shop.



However you go about constructing one of these, use an unambiguous toggle switch for your on/off switch, and label it unambiguously 'ON/OFF'.

I used a seven-foot, 18AWG line cord. 16AWG would have been better, but 18AWG is adequate for relatively short lengths.

Next up are some quick-connect/-disconnect motor line cords. I have four. First is one with big alligator clips on it, like so.


I didn't have clips with the correct colours of jackets on them, so I have to mind my wire colours when hooking up this cord -- not too difficult to do.

Here's a view of the cord connected to an old brute of a 1/2 hp motor.


In the example shown above, the clips and wires showed no tendency to shift about and short together, so I didn't bother with insulating tape. If a set of connections looks at all 'shaky', then by all means wrap the exposed bits with tape for safety's sake.

My second motor cord is one with two smaller alligator clips for the line connections, and a fork terminal for ground.


Third is a cord with three 1/4" spade terminals on it.


And fourth is a cord with three fork terminals on it.


Those four motor cord configurations will handle just about any motor connection scheme you're likely to run across.

The keys to safe use of the gear are these:
  • An unambiguous, unambiguously labelled on/off toggle switch; preferably one with a high operating force and an accompanying, pronounced 'click'. No mushy rocker switches or push/push switches. You don't want a switch type that might lead to an unwelcome surprise.
  • Apply insulating tape as required if there's any likelihood of connections shorting.
  • Arrange your switched outlet box and cords so they can't possibly get snagged in the works of whatever you're testing.
I find having the five above items at hand is a great time and aggravation saver.

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