I'm replacing my range with a separate cooktop and oven. The range is
on a 60 amp 240V circuit.
The new appliances have the following electrical requirements:
Oven: 30 Ampere, 208/240 Volts.
Cooktop: 40 Ampere, 208/240 Volts.
Also the manufacturer recommends a time-delay fuse or circuit breaker
and a separate circuit for each.
Can I use the existing 60 amp circuit for both?
If I need to get two circuits in there, can they share the same
Both appliances will be connected wire-to-wire (no plugs). Can I use
the same box for both of them?
P.S. I'm getting conflicting answers and a wide range of quotes from
electricians, so I wanted to get a better idea.
What you can (or maybe lucky to get always with) and what you should do for
ultimate safety, are different things. The manufacturer has a reason for
the requirements. I sure as hell won't tell you to try it knowing the
recommendations are different.
You can do anything you want (unless it's getting inspected), because it's
your house, and very few people will care if you burn it down.
What you are SUPPOSED to do, is install one 30amp breaker and one 40amp
breaker. Then run two separate lines to each appliance. It's ok to use the
existing wire for one of the circuits. You can probably use the same box for
both wires, but every box has a maximum capacity, mostly for heat build up
Assuming you mean "Should I . . .", the answer is no, since the
manufacturer recommends using separate circuits.
240V circuits don't have a neutral, and your two circuits should not
share any wires.
If the box is large enough. That's entirely a box fill issue, as far
as I know.
My suggestion: leave the existing 60 amp wire and box, change its
breaker to 40 amps, and use it for the 40 amp load. For the other
load, run a separate, new, 30 amp line with a new box.
Thanks Wayne. That's what I'm going to ask my electrician to do. I hope
fishing the #10/3 thru the steel conduit with #6 wires in there won't
be a problem. The good news is, the breaker box is also in the kitchen.
As far as some of the other replies go, I have no intention of going
against the code, but as I said in my first post, I got conflicting
answers from licensed electricians, and just wanted to clarify things.
If any licensed electrician told you anything other than using two separate
circuits, stay away from him. Fishing a new wire next to an existing wire in
a conduit is sometimes a pain. Depending on the size of the conduit, it
might be easier (and faster) to use the existing #6 wire to pull 2
completely new sets of wire.
I had this come up at a friends. The wire was plenty heavy, and the
breaker box a LONG way away, with all plastered basement cielings.
so we put in a sub panel in the kitchen to serve the 2 circuits and
saved lots of work!
This is what I got from the NEC handbook 2005 (Article 220, table
"..the branch-circuit load for a counter-mounted cooking unit and not
more than two wall-mounted ovens, all supplied from a single
branch-circuit and located in the same room, shall be calculated by
adding the nameplate rating of the individual appliances and treating
this total as equivalent to one range."
The handbook also explains (has a picture 210.21) how to pick tap
conductors when installing oven and cooktop on the same circuit under
210.19(A)(3) Exception No. 1.
Table 220.55 lists the max demand for a <12KW range as 8kW (derating it
assuming the range is not used to its full capacity).
The handbook has an example that shows how to get a combined rating for
multiple appliances. In my case, the cooktop is rated at 9.6kW, and the
oven is at 7.2kW. According to their formula, my combined maximum load
is 10.4kW which requires 43.3 amps.
Is anybody familiar with all this? According to this rule, shouldn't I
be able connect the cooktop and the oven to the same circuit (60 amp)?
Yes, I would agree with your summary.
Note that the branch circuit is limited to a max of 50 Amp rating,
so you would replace the 60A breaker with a 50A unit.
On a side note, if the raceway will be used as the equip ground
(raceway does not contain a grounding conductor), I would
verify the integrity of the raceway connections (fittings)
to perform as an effective grounding means.
I havn't looked at this stuff since about 1903 but my reading of the
210.19A3 requires the circuit for a range to be at least the rating of
the range and/or cooktop
422.10A allows the branch circuit for household cooking units to be
sized from 220.55
220.55-table-note 4 allows combining the KVA values and treating as a
220.55-table-note 1 the value that can be used for your units is
8KW +(5x5%) = 10KW = 41.7A @ 240V
(this is different from the value you came up with but still a 50A circuit)
210.19A3-exception 1 allows tap conductors to your cooktop to be rated
20 amps (or larger) if
the circuit they are tapped from is protected at 50 amps
and tap conductors are large enough for cooktop
and the tap is only as long as it needs to be
(this requires you to reduce the 60A circuit to 50A as noted in Jim's post)
422.30 requires a disconnect for the units
422.31 allows a circuit breaker to be used as the disconnect but only if
in sight of the appliances or if equipped with a device to lock it open
(not likely in your case)
422.33A allows an accessible plug and receptacle to be used as the
disconnect (that is one reason ranges are commonly connected with plugs)
422.33B allows a plug and receptacle to be used as disconnect for a
range if it can be reached by removing a drawer
422.16B3 allows wall mounted ovens and cooktops to be cord and plug
connected if the plug and receptacle are rated for the temperature they
are exposed to
210.21 allows a receptacle to be sized acording to 220.55 (instead the
unit KVA size)
(Presumably you need to figure out a disconnecting means - I don't know
what is common for hardwired units. Good question for the inspector.)
You are right: 8 + ( 8 x 24%) = 9.92. (I had used 8.4kW instead of
7.2kW, but forgot to update in the post.)
in sight of the appliances
These are going to be hard-wired, but the circuit breaker (panel) is
also in the kitchen (right across from the oven and cooktop), so I
assume I'm covered there.
I'll reduce the circuit to 50 amps. (BTW, I already have a #6 cable
Thanks Bud, thanks Jim.
Bud, you are right. For 7.2kW, combined kW is 8 + 8 x 24% = 9.92. (My
calculations were based on 8.4kW instead of 7.2, and I forgot to update
The circuit breaker (panel) is actually in the kitchen (just across the
oven and the cooktop), so I assume I'm OK. I'm going to reduce the
circuit to 50 amp (use the existing 6 gauge cable).
no, no, and subject to local code the box is probably too small.
a licensed master electrician who sees the jobsite and your appliance
and its manual will give you the best answer. and the electrical permit
inspector will make sure he's correct.
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