3-220 appliances 2 circuits

[Blain Plantz]

A 1940s home with an upgraded service panel late 1990s. This home has an A/C unit a stove top and a remote separate oven (all electric). The labels do not identify the circuits but it seems reasonable that the stove and oven are on the same circuit they both operated with one of the circuits off. I did call this out for further evaluation and hazardous Does anyone have more input could there be reasons why this would be okay?

thank you
Blain

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[Jack Feldmann]

Could there have been another panel with two 240V breakers for the oven and cooktop in the kitchen? I have seen them inside the cabinets under the cooktop.

[Vern Heiler]

As long as any splices are correctly made in a junction box, why would it be any more hazardous than a range with top and oven together?

[Blain Plantz]

There might have been a sub panel under the stove top, there was not a label in the main panel. I did not see any junction boxes or sub panels but there could have been something under the stove top. I did not look specifically for that.

Thanks I appreciate the input
Blain

[Blain Plantz]

Vern,

I don't have a good answer for you. All I can say is here in Colorado in every county that I have see if the stove top and oven are separate they each have a circuit.


Blain

[Lou Romano]

I am not sure if it has changed in the latest NEC but it used to be perfectly legal to connect the oven and a cooktop on the same circuit. It also used to be ok to connect the AC AHU and CU on the same breaker and still is under certain conditions.

The AC heat and cool are what is called non-coincidental loads! The two are never both on at the same time. Also alot of times a 50-60 amp circuit is run from the main panel to the AC AHU closet where a small 4-circuit panel is installed and then both the AHU and CU are fed from this panel. There are other ways that this can be done legally as well. Another way is to take the largest of the two loads AHU or CU and run the proper size wiring for the larger to both and then fuse down to the lesser load in the disconnect at the unit. Both these options allow you to have them both on the same breaker in the main panel.

I don't remember the exact restrictions there are/were on the oven and cooktop sharing a circuit because I always ran individual circuits for them, but I am sure Jerry or someone else will chime in soon with that info.

[Bill Kriegh]

I am not sure if it has changed in the latest NEC but it used to be perfectly legal to connect the oven and a cooktop on the same circuit.

Still is - and often done, even in Colorado

[Jerry Peck]

I am not sure if it has changed in the latest NEC but it used to be perfectly legal to connect the oven and a cooktop on the same circuit.

Still is - and often done, even in Colorado

The answer is: It depends.

If the nameplate rating on the equipment states a maximum overcurrent protection rating, and the separate range and separate oven are on the same circuit, which has been oversized for each individually and is suitable for both, the overcurrent protection would need to be sized for the maximum of the conductors - which is hopefully been sized for the maximum of both appliances, which would result in the overcurrent protection exceeding that specified by either individual appliance if so stated on the nameplate.

I haven't looked at a nameplate of a range or separate oven in quite sometime - does anyone know if the nameplate gives a maximum overcurrent rating size? If so, than 110.3(B) would need to be considered.

[Roger Frazee]

Range nameplates usually only state voltage requirements and max. kilowatts. I've never seen a range nameplate state max. ocpd.

You will be hard pressed now days to find a manufacturer that does not state in the installation instructions that an individual branch circuit is required. Notice I did not say recommended.

It is common however to see two cooking appliances on the same branch circuit and many times the second appliance is served by tap conductors to a 50 amp range branch circuit. This is provided for in NEC 210.19A3


So as Bill stated it is very common.

[H.G. Watson, Sr.]

There is a 50% rule. Unlike most older free-standing "Ranges", Wall Ovens and Cook tops are and were considered fixed in place, not easily moved.

Both devices require a means to disconnect, for servicing, etc. whether via a cord set/receptacle or a local individual disconnect, or a remote lockable individual disconnect. Depending on Code cycle in place during re-model/re-wiring expect both still simply wired not 4-wire configuration unless having special features (downdraft cooktop, convection oven, combination wall oven/microwave, etc.).

Presummed UL Category Code/Listing Standards are those of purely RESIDENTIAL Cooking Appliances - NOT Commercial + If Commercial only shouldn't be in residential environment; If dually listed - then there would be requirments for individual circuits with individual protection when in residential environment.

Wall Oven and Electric Cook Top ARE coincidental loads, not "non-coincidental". Both are fixed in place, attached, not easily moved cooking appliances.

The maximum rating for both (and the cook top would be all "burners" combined at max rating/setting, and that of the wall oven - and if more than one "oven compartment - all such, on maximum - if a cleaning cycle present - that is usually the one drawing the highest kW). If the wall oven has a combination microwave generally will not allow by its listing and instructions sharing of the circuit; often if a convection will likewise not allow sharing of the circuit (other than pure resistance load). Neither appliance's maximum rating may exceed 50% of the circuit rating to be shared. There could be no other outlets, except perhaps a clock outlet.

Listing requirements for such appliances have actually changed some over the years. Older controls for example: push buttons facing up towards the ceiling; are considered safety issues and no longer allowed; vintage of the appliances makes a difference, regarding safety issues an HI reports beyond what may have been allowed in the 40s, 50s, 60s, 70s and early 80s, as opposed to what was no longer allowed example 90s.

Unclear if the cooktop and the wall oven units are "vintage" or more recent, the older likely listed to 30A max OC protection. The appliance(s) manufacture date, the Listing Standard (dated edition) at the time of manufacture - and of course the Listed Appliance's instructions would have the appliacable information. You might also check the UL White Book Category Code applicable (referencing the older edition applicable to the appliance('s) date of manufacture, not the present one).

Generally, older, "plain Jane" electric cook tops and electric wall ovens purely resistive loads and generally required limitation to the circuit supplying same. On-board supplemental limiting more recent abberition.