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View Full Version : 100 Amp panel vs 325 Amps worth of breakers?


jadrma
Oct 24, 2008, 09:30 AM
I have a house built in '49. The basement was remodeled by previous owner and the Service Panel was upgraded to 100 AMP. The wiring to the breakers are a mixture of modern sheathed 3 wire for the basement level and the original knob and tube wiring for main floor circuits (all fed via the attic). It appears the work is properly done and the wiring in the panel is neat and orderly. However, the total sum of the breakers in 325 Amps (much of this devoted to several baseboard heaters which were added to areas not served well by the original oil furnace ducting). I've heard it should not exceed 180% of the Panel Rating. Am I at risk?

Also, in examining this... I notice the stove circuit has the two hot wires going to the appropriate breaker but the 3rd wire (neutral?) is simply capped off with a wire nut inside the panel. Shouldn't this go to the grounding bar?

tkrussell
Oct 24, 2008, 09:54 AM
Adding the rating of each breaker in any panel is irrelevant. The number means absolutely nothing. If your concerned, then a service rating calculation needs to be done. This involves several varibles unique to each building.

The 180% is either a typo, or your misinformed, there is no such thing. The issue is a circuit breaker cannot be loaded more than 80% of it's rating, for loads that are continuous, operates more than 3 hours.


The range may not need a neutral, so it is capped. There should be another equipment ground wire. If there is no ground wire, then the neutral would act as the ground for the range. Need more detail on this.

Some of this will be difficult to explain, and get all the proper information from you, to answer the calculation question accurately. If there is some question in your mind if the service is large enough, I suggest you call in an electrican and have the system surveyed and ask for the calculations be done.