I have a 40Amp breaker at the box on the circuit for my cooktop. I also have a 30amp breaker on the circuit for my single wall oven. Both circuits have what appears to be #6 wire. Wire is a bundle of 7 .060" wire solid wire conductor and diameter of bare bundles is .170-.180". Why would house be wired with what I assume is 50A wire and have smaller breakers? I am wanting to put in a 50A cooktop and a 40A double wall oven. My assumption is that I can just replace the ckt breakers, theat the wiring is fine for 50 Amps. The 40 Amp run is probably about 45 foot and the thirty Amp run is about 40 foot.

The problem is the service you have. If you have everything in the house running at once you could overload the wires and cause a fire. How many amp service do you have from the main power panel and how much do you have in circuit breakers under that?

I have 200 amp service box with I assume tobe a total of 430amp in breakers. The oven has two 30 amp breakers, the cooktop has two 40 amp breakers. Do I count them as 30 and 40 amps total respectfully or do I count them as 60 amps and 80 amps respec

bpwarne : I have 200 amp service box with I assume tobe a total of 430amp in breakers. The oven has two 30 amp breakers, the cooktop has two 40 amp breakers. Do I count them as 30 and 40 amps total respectfully or do I count them as 60 amps and 80 amps respec


I would assume that the cooktop and oven are 220. And the service is 220. So having a total of 430 amps worth of breakers your already at the limit for your service. At 200 amp anything running on 220 counts directly against the amp count. Anything on 110 would be 1/2 of the amp count for calculating load on the original 200 amp service.

A conductor with 7 strands of .060 wire would seem to be #6 AWG. Therefore, you are correct that the cable can handle 50 amp max. So you should be able to use this cable for both the 50 amp and 40 amp feeders to the new appliances.

I have no idea what the answer you have received already means.

Adding circuit breaker amp ratings of all branch circuits in a panel means absolutely nothing.

The standard voltage in the USA is 120 and 240 volts.

Here is where we are going to disagree. I think it may be a misunderstanding. Each branch circuit represents a "load". It's a potential of value. So if you only have 200 amps to work with. Then the potential amps to be distributed is also 200 amps maximum without exceeding the rating. So yes it does matter if that is how the circuit is designed. There is always the planned potenial for everything to be "turned on" at one time. That is why it is important.

Hope that makes more sense to you now.

Then you are disagreeing with every qualified professional electrician out there.
The sum of the breakers is a MEANINGLESS number!


Completely false. The calculated load is what is planned for. NOT that everything in the home will be turned on at once.

You can disagree with me all you want, and try to justify your advice, however, it is still incorrect.

Read Article 220 of the National Electric Code, understand how each branch circuit is sized, and how a service sized sized, you will see that adding amp ratings of circuit breakers is irrelevant.

Amen!

Quote from article.
The branch-circuit loads are combined with other applicable demand factors in Parts II, III or IV to determine feeder and/or service loads

Ref:

Electrical Contractor: Article 220-Branch Circuit, Feeder and Service Calculations


Maybe I wasn't explaining myself right. But this says the same thing. The advice I was giving is based on worst case and not to exceed.

Cal,

There are two type of loads:

Connected load - the physical wiring.

Calculated Load - The anticipated load at any given time.

All circuit sizes are based on the calculated load, not the connected load.

Then that was my misunderstanding. I appologize.

BPwarne... have we totally confused you yet?