220v circuits

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Old 04-07-08, 07:43 AM
W
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Smile 220v circuits

I am getting a new double wall oven which requires a 40 amp circuit. The current circuit breakers for the line has two 30 amp CB's. My question is :

do I currently have a 240v 30 amp service or a 60 amp(30+30) service

Thanks
 
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Old 04-07-08, 07:56 AM
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You currently have a 240V, 30A circuit for the oven most likely wired with #10 wire. You will need to replace the cable with #8 cable and replace the breaker with a 40A double-pole breaker.

If the oven requires only 240V, use an 8/2g cable. If the oven requires 240V/120V, use an 8/3g cable. I would recommend using the 8/3g cable in either case so it will be compatible with a wider variety of future ovens.
 
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Old 04-07-08, 08:01 AM
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Thanks for your help
 
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Old 04-07-08, 01:29 PM
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IB,

how is the weather in lansing today? Here in Port Huron it is 65 and sunny. )

How would I pull a 120VAC line from an 8/3g cable? Just curious. Pull off one of the legs and use the neutral for the 120Vac?
 
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Old 04-07-08, 01:44 PM
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From what 8/3 cable for what purpose?

If it is an 8/3+gnd that is serving no purpose, you could install a sub-panel, or chang the breaker to 15 or 20A, and connect 15 or 20A receptacles.

Otherwise you need to run a separate line for your 120V load.
 
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Old 04-07-08, 02:20 PM
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Originally Posted by Thonati View Post
how is the weather in lansing today? Here in Port Huron it is 65 and sunny. )
Beautiful finally! I just got a puppy this week, and he's having a ball playing outside in the sunshine.

How would I pull a 120VAC line from an 8/3g cable? Just curious. Pull off one of the legs and use the neutral for the 120Vac?
Are you looking to use this cable for just a 120V circuit or for both a 120V circuit and a 240V circuit at the same time?

In either case, you could use one or both of the hots and the neutral provided that you replace the breaker with a 15A or 20A and follow the other rules regarding multi-wire circuits. It would not be legal to pull off a 120V circuit with the original 40A breaker in place. As a practical matter, #8 will not fit into the terminals on a 120V receptacle so you would need to use crimp spades or wirenut to a short pigtail of #12.
 
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Old 04-07-08, 02:40 PM
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I think the 110v circuit got interjected into the discussion only because modern range/ovens utilize 110v for lighting, etc, and THAT requires a neutral in addition to the 2 wires for 220 and 1 for a ground, hence the need for 8/3 plus a ground.

No one really meant this circuit to be used as a 110v circuit in addition to a 220v circuit.
 
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