[rting]

I have a Federal Pioneer Stab-Lok BE 132-64 200Amps 120/240V 1 phase 3 wires circuit breaker panel with a 30AMP circuit breaker hooked up to an existing electric cooktop.

Existing electric cooktop is a Jenn-Air CCS446-C cooktop with the ratings 7,000W at 240V / 208V.

Need to hook up a BOSCH NET5054UC cooktop to it - it is rated at 7,700W at 240V /208V.

Have I exceeded the limit of the 30Amp circuit breaker?

[tkrussell]

Yes, you would have 32.08 amps on the 30 amp circuit with the new unit.

This needs a 40 amp circuit.

Even the 7000 watt unit is too large for a 30 amp circuit.

[rting]

Thanks tkrussell. I am really confused now... The current unit never had a problem and in addition, it is rated also at 5,300W 208V. Moreover, local major appliances dealer told me that they do not have alternatives under 30Amps. The BOSCH unit manual has 40Amps under 240V and 30Amps under 208V in it's installation manual. Can you help me understand why:
1. Two voltages listed in the manual.
2. And how each set of numbers is used with the 30Amp circuit breaker.

[tkrussell]

Do you have 240 or 208 volts? I assumed 240, since that is typical. There are some homes with 208, but usually only apartments or condos in large buildings.

7000 watts divided by 208 volts = 33.65 amps

7000 watts divided by 240 volts = 29.17 amps

A 30 amp circuit shall not have more than 24 amps of load, no matter what voltage.

You have not had a problem with the breaker tripping probably due to not using all the burners at once, or often.

In any case, your new unit needs a 40 amp circuit if you have 240 volts, and a 50 amp circuit if you have 208 volts.

[rting]

I understood the math... (long story with my education there)

I am in an apartment and everyone is telling me that it is 208 volts - I have a voltmeter but cannot find a spot on the circuit to measure - where can I measure?

The original unit (Jenn-Air) is rated at 5,300 watts at 208 volts. Which means 25.48Amps. If the voltage change, the wattage should change too - you may be incorrect in dividing 7k watts into 208 volts.

For the BOSC NET 5054UC installation instructions: -
See page 9 of the first document here: https://portal.bsh-partner.com/TCcustomBSH/controller/download_file?PDFOBID=tgslirkcdcso0pdmdb---j4p&UMOBID=tgsliqecdcso0pdmdb---j4p

I can't seemed to find the other cooktop's specs except to include a picture here: https://picasaweb.google.com/ting.roger/JennAirCCS446C?authkey=Gv1sRgCNO9tcftnumYQg&feat=d irectlink

[rting]

Appreciates all the comments so far!

[tkrussell]

As I said, large apartment buildings will commonly have a 208 volt system.

You will be fine with the new unit on the existing 30 amp circuit, as per the manufacturers specifications and instructions.

The unit is rated 7700 watts at 240 volts. The wattage is reduced proportionally to the supplied voltage, so at 208 volts the wattage and current is reduced.

The constant value of the heating elements is the resistance.

First, amps are 7700 watts /240 volts = 32 amps

Ohms Law states R=E squared/P

R= 240 x 240 / 7700 = 7.5 Ohms

Next I=E/R

I = 208/7.5 = 27.7 Amps

P = 208 * 27.5 = 5761 watts