240 volt beaker problem

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Old 05-19-08, 08:29 AM
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240 volt beaker problem

Hello hopefully somebody can help me ... I am trying to install a 240 volt receptacle in my garage. heres my problem when i install the dual pole breaker into the panel i only get 120 on each pole but when i test both poles i get a reading of 0 , i thought it maybe was my breaker but i tried it on two different ones .. any ides??? using federal stab-lok breakers
 
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Old 05-19-08, 08:44 AM
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You installed a tandem (AKA twin or skinny) breaker. Except is a very few panels (e.g., certain GE panels), you cannot get 240 volts from that. Generally, you need a double-wide breaker to get 240 volts, although you can sometimes save space by using one quad breaker to get two 240-volt circuits.
 
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Old 05-19-08, 08:49 AM
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Inside a normal residential breaker panel, there are two 'busses' which connect the main supply to the breakers. In a normal installation, each bus is 120V to neutral, and 240V to the other bus.

The most likely situation is that you purchased a 'skinny' or 'tandem' breaker. This is actually a pair of single pole breakers that fits into a single slot. Both of these breakers connect to the same bus, so that you will never get 240V. Additionally, the two poles don't have a proper 'common trip' needed for a 240V application.

Sometimes (very rarely) the two busses are connected to the same leg of the supply, making a '120V' panel. Such a panel cannot supply 240V loads, even with proper breakers.

Certain breaker panels actually have true double pole skinny breakers; depending upon the position in the panel the two poles will end up on the same or different busses; to get 240V you need the two poles on different busses.

Finally, if one of the supply legs has been damaged and disconnected from the POCO supply, you can still see voltage on that buss as current passes through various 240V loads from the working leg. You would be seeing significant electrical problems throughout your house if this were the case.

-Jon
 
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Old 05-19-08, 10:00 AM
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okay heres what i did i moved the breaker to the other side of the panel now works.. does this mean i have a damaged panel? sorry if this somes stupid just new to this
 
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Old 05-19-08, 10:16 AM
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It either means that you have a damaged panel, or that you moved it to a location that hits both bars. Without more information, we just don't know which.
 
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Old 05-19-08, 04:20 PM
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i never had the position over two bars.. works on both sode .. thanks for all your help
 
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Old 05-19-08, 04:29 PM
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Federal Pacific "STABLOKS" are a known problem, and strong consideration to replacing the panel is advised.....

Not necessarily side to side....But it is entirely possible to put a Stablok Breaker in the wrong slot, and cause exactly what you had. Moving it over 1 full space will cure the symptoms.
 
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Old 05-19-08, 06:53 PM
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In FPE panels it is possible to install the double pole breaker and only hit one bus bar. You need to move the breaker up or down one slot to get 240 volts.
 
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