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Neil_K 11-06-2004 09:52 PM

single vs. double breaker
Other than size, why would one use a double 40 amp breaker versus a single 40 amp breaker? I am building a small shop and plan on running power to it. I plan on putting a subpanel in the shop and have been told by one person to use a double and another to use the single breaker in the the main panel. I know that I'll need #8 wire. Thanks.

Hammertime 11-07-2004 12:07 PM

single breakers are 110v/120v(one power wire) and a double breaker is 220v/240v(two power wires) If you're wiring for a shop and you're going to be running machinery with high wattage or amperage ratings then you'll be better off with the double breaker. This way if youi're drawing a lot of amperage from one of the power feeds comiing out of the main breaker then you still have a fresh power source from the other feed. This is only really necessary if you plan on future power anticipation. If you're anticipating using a high draw of power in the future then you'll might want to increase the wire size to #6 and also depending on the distance the sub-panel is from the main panel. If you're going to run a basic work shop with simple power tools for a small sub-panel then a single amperage breaker will do. What you should do is sit down and figure out your wattage rating usage on your tools and what you might plane on hooking up in the future to add to the load you'll have initially to see if you'll be running what you'll need. Just figure out your wattage by adding up what you plan on running in your shop and divide that by the voltage being used and that will give you the amps that will be needed for your subpanel main breaker.

Neil_K 11-08-2004 10:25 PM

Most likely, it won't be more than one power tool at a time, and maybe a small air compressor or something. Lights would be on a separate breaker in the subpanel. Of course, that window a/c unit would be nice. Thanks.

Teetorbilt 11-14-2004 11:02 PM

The real work is in getting the wire to the shop, might as well go 220 to the subpanel just in case you ever need it.
Once that I had juice to the outback the wife found all sorts of uses for it, like low voltage lighting. I also moved the well and pool pump out there, much quieter in the house and the sun isn't beating all of the equipment to death.

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