Purpose Of 30amp Single Pole Breaker - Electrical - DIY Chatroom Home Improvement Forum

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Old 02-16-2010, 01:25 PM   #1
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Purpose of 30amp single pole breaker

What is the purpose of a 30 amp single pole breaker?


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Old 02-16-2010, 01:30 PM   #2
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The only time I have used one it was for an RV hookup or a UPS for a server room.


Last edited by Jim Port; 02-16-2010 at 01:43 PM.
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Old 02-16-2010, 01:37 PM   #3
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I have 2 at work in the telco demarc room, 18-30R plugs for two 208 volt UPSs. They keep our metropolitan area network running (gigabit Ethernet links to other sites in this same metro area). The telco equipment has transformers that make the 208V AC in to 54V DC to power the equipment. The UPS's plug into the wall and the telco stuff plugs into the UPS's. Both have twist-lock plugs.
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Old 02-16-2010, 02:01 PM   #4
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I've only seen them (legally and safely) used for the things mentioned; computers/UPS/servers and travel trailers, along with commercial hand dryers.
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Old 02-16-2010, 09:17 PM   #5
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I recently installed one for my RV outlet - a TT-30R recept.
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Old 02-16-2010, 09:30 PM   #6
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I've seen them used for RV receptacles and point-of-use water heaters for residential.

For commercial/industrial, I've seen them used for machine control panels, generator and motor winding heaters, 277 volt parking lot lights (277 volt breaker), streetlights, an occasional piece of equipment that needs more than 16 amps, but less than 24, computer equipment, and others I can't think of right now.

The largest 120 volt single pole breaker I've installed was a 60. Most traffic light controllers have a 50 or 60 amp single pole as the main. They don't draw all that much current, (Incandescent ones are about 25 amps or so, LEDs are less than 10), but they don't want the main to trip without a very good reason.

If a pole gets knocked down, or a wire gets shorted somewhere, it'll usually blow one or more of the loadswitches out. The conflict monitor will see this, and will send the signal into flashing red. If the main were to trip, the signal would be dark. Obviously, flashing red is much safer than no lights at all.

The most common use though is because a 15 or 20 trips, and uncle Bob says 'Put a 30 in, it won't trip then'.
This usually solves the tripping problem, but creates a new, much larger problem. Generally, a fire.


P.S. I've seen maybe a dozen or so legitimate uses for 30 amp single pole breakers in houses in 20 years of doing electrical, but the big box stores always seem to have an ample supply of them. Makes ya wonder sometimes!


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