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Replacing single drop-in range (oven/stovetop) with separate unit

Posted by staze (My Page) on
Sun, Mar 17, 13 at 17:37

All,

I'm looking to replace a single unit drop-in (combination oven/stove top) with separate stove top and oven (in the same location). Right now, the unit has a single 60amp circuit running to it. Is there a way, or is it code, to basically branch this wiring to the two separate units, or daisy chain them somehow? Maybe just terminate the circuit into an electrical box in the space, then have wires run to the stove top out of the box, and then others to the oven?

I would rather not run a new circuit, but if I have to, then no huge deal... since the current combo unit runs off the existing 60 amps, I would think two separate units would just as easily run off 60 amps... it's just a matter of how the wiring works.

Thoughts?


Follow-Up Postings:

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RE: Replacing single drop-in range (oven/stovetop) with separate

The easiest way may be to drop the breaker to 50A and then tap off two 20A or larger conductors:


Exception No. 1: Conductors tapped from a 50-ampere branch circuit supplying electric ranges, wall-mounted electric ovens, and counter-mounted electric cooking units shall have an ampacity of not less than 20 amperes and shall be sufficient for the load to be served. These tap conductors include any conductors that are a part of the leads supplied with the appliance that are smaller than the branch-circuit conductors. The taps shall not be longer than necessary for servicing the appliance.

The other way would be to install a small subpanel and use the stove circuit as a feeder (if it is a 4 wire hookup).


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RE: Replacing single drop-in range (oven/stovetop) with separate

I'll second Ron on using the branch circuit tap rules- changing your existing circuit should be relatively quick and easy. Just remember that any splices/taps have to be made inside an accessible box- do not bury them in the wall. Good luck with your project- Mike


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RE: Replacing single drop-in range (oven/stovetop) with separate

"shall be sufficient for the load to be served."

This sets the size of the taps.
20 amps is the minimum size that MAY be used so that the wires can carry sufficient fault current to trip the circuit.

It NOT a permission to use 20 amp conductors to supply a greater than 20 amp load.


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RE: Replacing single drop-in range (oven/stovetop) with separate

Sort of in the same boat.

The simplified electrical code book i got (Canadian) says a cook top and oven shall be considered as one appliance....but also says one appliance can only have one point of connection to the supply. So you have to daisy chain it, at least here.

It says the the distance of the junction in the tapped line can be not more than 25 feet with #10 wire. There is an exception in that if it needs over 25' it can be but the cable must be the same size as the main supply cable and that in most cases this is #8 wire.

My issue is what happens if i want 2 ovens? does that still count as one appliance? how about 3? 4? At what point do i need to drop to a #6 wire?


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RE: Replacing single drop-in range (oven/stovetop) with separate

Check your oven installation instructions. Almost every dual oven I've seen is really only one device (only gets one connection).

This post was edited by ronnatalie on Sat, Apr 6, 13 at 8:14


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RE: Replacing single drop-in range (oven/stovetop) with separate

@ronnatalie - not dual ovens, 2 ovens.


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RE: Replacing single drop-in range (oven/stovetop) with separate

"It says the the distance of the junction in the tapped line can be not more than 25 feet with #10 wire. "

Under the NEC that would allow for 80% of a 30 amp load on those taps.

I would bet the CEC is about the same.

You still have to meet the demands of each device with the wires feeding the device.

The tap rules allow you to use smaller than feeder size, NOT smaller than demand size.


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RE: Replacing single drop-in range (oven/stovetop) with separate

@brickeyee - Good distinction.

Would it be better to say the tap can be 25 feet maximum at demand size for the device and that if it must be longer it needs to be the same size as the main?

how do you calculate demand/wire gauge?

Edit:
Code in my area says the following about load calculations.

For a range 12kw or smaller add 6000watts
if greater than 12kw add 40% of the amount over 12kw
If adding a second Range/oven add 25% of its total wattage.

so a 14kw range with a 10 kw secondary should be as follows.

First 12kw = 6000watts load
14kw - 12 kw = 2kw = 2000 watts
2000watts x 40% = 800watts Load
Second oven 10kw x 25% = 2500 watts

First oven = 6800 watts
Second oven = 2500watts
Total = 9300 watts

I have read else where that we can only consider a 85% efficiency so that total needs to be upped to compensate for that.

9300watts x 1.25 = 11625 watts in this hypothetical scenario.

This is what i get according to the numbers, but that second oven only getting 25% of its capacity bugs me. Is this because they expect you to not use both at once? Turning everything on would trip the breaker wouldn't it?

All this says nothing about cable size.

Here is a link that might be useful: Found a link about wire type/temp and size.

This post was edited by Noctua on Sun, Apr 7, 13 at 15:44


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