Coverting from range to cooltop / wall oven

[Ray_G]

Hello –

I have a couple of questions that relate to replacing a range with separate cooktop / oven components. My ‘old’ range used a 50A ungrounded 3-wire feed. I plan on abandoning this wiring and running two new grounded 3-wire runs to service a 40A cooktop and 30A wall oven. The manufacturer (KitchenAid) calls for 8 gauge solid copper wire for both units. Here are the questions:

1. Does it matter if the wire is stranded (flex) or solid? Is there practical reason to select one over another?
2. The wire from the appliances is 12 AWG, so I will be bonding 8 to 12 AWG at the box. “Red” wire nuts seem to be sufficient according to the charts I’ve seen, but should I use gray (or another fastening means)?
3. At the service panel I noticed that Murray makes a quad breaker (MP230240) that permits both appliance feeds within two panel slots. I recently upgraded to a new 40 slot 200A panel for a typical colonial home and I need to save a few slots for standard 15A service runs - so this is an attractive option. Assuming I am within service load capacity, are these quad units frowned upon in any way?

Thanks for your help. Any other tips / suggestions are gratefully accepted and appreciated. This forum is amazing!

Ray

[Wgoodrich]

YOU SAID;
1. Does it matter if the wire is stranded (flex) or solid? Is there practical reason to select one over another?

REPLY;

The NEC requires any conductor except for a special few to be stranded wire when exceeding 10 awg in wire size. Grounding electrode conductors would be one of those few exceptions to this rule. You will be required to use stranded wire per NEC rules.

YOU SAID;
2. The wire from the appliances is 12 AWG, so I will be bonding 8 to 12 AWG at the box. “Red” wire nuts seem to be sufficient according to the charts I’ve seen, but should I use gray (or another fastening means)?

REPLY;

Red wire nuts should be listed to accept one 8 awg and one 12 awg wire. Make sure you are not mixing copper and aluminum under the same compression connection with the two dissimilar metals touching unless you use a specifically listed connector for that purpose.

YOU SAID;
3. At the service panel I noticed that Murray makes a quad breaker (MP230240) that permits both appliance feeds within two panel slots. I recently upgraded to a new 40 slot 200A panel for a typical colonial home and I need to save a few slots for standard 15A service runs - so this is an attractive option. Assuming I am within service load capacity, are these quad units frowned upon in any way?

REPLY;

You will not be allowed to install 1/2 size breakers as you mentioned for one or two reasons. First the Code allows only a maximum of 42 circuits within a single 200 amp panel. Second if you were allowed with that rule your panel would have to be approved for 1/2 sized breakers and if this is a full 40 circuit panel then no it would not be approved. Then if the panel allows it you must use a 1/2 sized breaker that is listed for use in that certain panel.

HOpe this helps

Wg

[Ray_G]

Thank you very much for the response. I am a bit unclear on the reponse to #3. It sounds as though the "42 circuit" rule in a 200A (40 slot) panel basically allows for two conventional 110 tandem breakers or one 220 quad unit as long as it is approved for that panel. Thus, oversubscribing the circuit quantity by 2.

Were you implying that the 40 slot panel is not likely to approve the use of tandems or did I miss the point you were trying to make?

Thanks for your patience and response, and yes, it was very helpful.

Ray

[Wgoodrich]

If you have a panel designed for all full sized breakers totalling 40 circuits then it will not allow 1/2 sized breakers.

Some panels are called for example 20/40 designed for half sized breakers yet only a total number of breakers whether half sized or not may be installed in that panel as it was listed and labeled.

Sorry

Wg