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Old 12-20-2009, 06:58 AM   #1
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Need Help with wiring old appliances


I have two older appliances that I need help with wiring. I have an an early 1980's Whirlpool stove that is currently on a 40 amp dual breaker (3 wire + GRD 120/240) and I also have a late 1980's forced air conditioning unit on a 60 amp dual breaker.

My question is what gauge wire (i.e. 8/3) should I be using for these two units? Also, I believe that stove should be on 30 amp breaker but I cannot find any specs on the unit itself. Where are the specs typically located on these units?

Last edited by tripower; 05-13-2010 at 06:03 PM.
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Old 12-20-2009, 08:17 AM   #2
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you need to determine what load and rating these units are requiring. This label is usually near the electrical access plate in the rear of the unit. you need #6 for 50 amps and #8 for 40 amps and #10 for 30 amps
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Old 12-20-2009, 12:47 PM   #3
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Most ranges can operate satisfactorily with a 40 Amp circuit: You can use #8/3 w/ground NM-B cable in most areas.

See if you can locate a nameplate on that AC unit. YOU are looking for 2 things:

1) Minimum circuit ampacity
2) Maximum overcurrent protection

Those will indicate your wire size and breaker size requirements.
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Old 05-13-2010, 06:33 PM   #4
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Need help with oven


Quote:
Originally Posted by kbsparky View Post
Most ranges can operate satisfactorily with a 40 Amp circuit: You can use #8/3 w/ground NM-B cable in most areas.

Here are all of the specs that I could gather on my oven:

WHIRLPOOL MODEL RB220PXK-0
30 INCH BUILT-IN CONTCNUOUS-CLEANING ELECTRIC OVEN

Kilowatts 208 volts - 3.5
Kilowatts 240 volts - 4.1

3 wire 120/208-240 volts 60hz AC only

http://shared.whirlpoolcorp.com/prod...rType=Consumer

I'm just not going to get behind that oven it is going to be a huge pain pulling it out from the cabinet. What I need to know is will the 40 amp breaker be appropriate for this oven or should I go down to a 30 amp or up to a 50 amp?
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Old 05-13-2010, 07:53 PM   #5
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4100w/240v = 17A, about as much as a water heater element.

Last edited by Yoyizit; 05-13-2010 at 07:56 PM.
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Old 05-13-2010, 09:18 PM   #6
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Originally Posted by Yoyizit View Post
4100w/240v = 17A, about as much as a water heater element.

Where do you get the 4100watts from?
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Old 05-14-2010, 01:24 AM   #7
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Quote:
Originally Posted by tripower View Post
Where do you get the 4100watts from?
From here:

Quote:
Originally Posted by tripower View Post
Here are all of the specs that I could gather on my oven:

WHIRLPOOL MODEL RB220PXK-0
30 INCH BUILT-IN CONTCNUOUS-CLEANING ELECTRIC OVEN

Kilowatts 208 volts - 3.5
Kilowatts 240 volts - 4.1

3 wire 120/208-240 volts 60hz AC only

http://shared.whirlpoolcorp.com/prod...rType=Consumer

I'm just not going to get behind that oven it is going to be a huge pain pulling it out from the cabinet. What I need to know is will the 40 amp breaker be appropriate for this oven or should I go down to a 30 amp or up to a 50 amp?
4.1 kW = 4100 watts
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Old 05-14-2010, 07:34 AM   #8
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Quote:
Originally Posted by kbsparky View Post
From here:
4.1 kW = 4100 watts

Understood. So can I use a 20 amp breaker or should I use a 30 amp breaker?
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Old 05-14-2010, 08:41 AM   #9
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Intuitively I find it hard to believe that a "30 inch electric range with 4 burners and self cleaning oven" can run on just 20 amperes (at 240 volts). I would wire it up for 40 amps (8-3 cable).

Could it be that the name plate with the 4.1 KW rating you saw was just for the oven portion (which in my mind would result in a lot of confusion)?

The power plug may (for an older appliance) or will (for a modern appliance) indicate the maximum circuit amperes rating by its shape and size. If you strung 6 gauge wire to future proof the kitchen for a bigger 50 amp stove later, you can use a 40 amp breaker for now.
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Last edited by AllanJ; 05-14-2010 at 08:51 AM.
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Old 05-14-2010, 08:47 AM   #10
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Quote:
Originally Posted by AllanJ View Post
Intuitively I find it hard to believe that a "30 inch electric range with 4 burners and self cleaning oven" can run on just 20 amperes (at 240 volts). I would wire it up for 40 amps (8-3 cable).

Could it be that name plate with the 4.1 KW rating you saw was just for the oven portion (which in my mind would result in a lot of confusion)?
I believe the OP was talking about a stand alone built in oven, not a cook-top oven combo.
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Old 05-14-2010, 09:52 AM   #11
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Quote:
Originally Posted by AllanJ View Post
Intuitively I find it hard to believe that a "30 inch electric range with 4 burners and self cleaning oven" can run on just 20 amperes (at 240 volts).
Check it, with all switches on.
(240v^2)/4100w = 57600/4100 = 14 ohms.

Depending on the trip curve, a 20A breaker may be able to hold 17A indefinitely, but the NEC may have something to say about this.

Last edited by Yoyizit; 05-14-2010 at 09:54 AM.
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Old 05-14-2010, 04:10 PM   #12
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Quote:
Originally Posted by Yoyizit View Post
Check it, with all switches on.
(240v^2)/4100w = 57600/4100 = 14 ohms.

Depending on the trip curve, a 20A breaker may be able to hold 17A indefinitely, but the NEC may have something to say about this.
Why would you possibly think that a 20 amp CB would not hold 17 amps indefinitely?
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Old 05-14-2010, 05:50 PM   #13
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I've run a 20a 120v breaker at 19a for my Christmas display for 5 hours without a problem

Since the stove isn't considered a continous load I don't see a problem



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Old 05-14-2010, 08:35 PM   #14
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Quote:
Originally Posted by brric View Post
Why would you possibly think that a 20 amp CB would not hold 17 amps indefinitely?
I think it would, but there might be some trip curve somewhere that won't.

If this one were a 20A unit it would hold at 20.8A forever.
http://www.accontrols.com/Typical%20...ip%20Curve.pdf

Last edited by Yoyizit; 05-14-2010 at 08:44 PM.
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Old 06-19-2010, 04:33 PM   #15
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Quote:
Originally Posted by AllanJ View Post

The power plug may (for an older appliance) or will (for a modern appliance) indicate the maximum circuit amperes rating by its shape and size. If you strung 6 gauge wire to future proof the kitchen for a bigger 50 amp stove later, you can use a 40 amp breaker for now.
So you are saying I could run 6 gauge wire now, and use a 40 amp breaker now then later move to a 50 amp breaker when and if I purchase a oven/cooktop combo?
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