Fuse versus Breaker Watts Loss / Greenhouse Gas Production Revision date: May 03 2012 10:14:23 CDT

Select the breaker(s) used in your project. If you have more than 10 different ratings, just run the calculator with the first set of breakers, record the results, then repeat with the next set of breakers. Continue until all breakers have been accounted for, then just sum the results.

The calculator will determine the watts loss for each breaker at the full load and compare the watts loss for an equivalently sized fused switch at the same load. The calculator will then compute greenhouse gas production differences and energy cost differences.

Note 1: Laboratory testing was only done at full load. Heat losses at less than full load are scaled by a factor proportional to the square of the current reduction (i.e. 90% load = 81% loss, 80% load = 64% loss, etc.)
Note 2: Fuses are discarded into the environment after they operate. Fuses contain silver, a metal that bioaccumulates in living tissue. The effect of this was not included in the calculations.
Note 3: NEMA states "Water may affect the filler material of fuses and will degrade the insulation and interruption capabilities." While certainly a concern should the fuses become water damaged, the condition of fuses may degrade over time as fuses absorb moisture in the air. This is especially a problem if power through the fuse is switched off in a humid environment or if applied in an environment where condensation is a possibility.

Circuit Breaker Type / Frame Fuse Type Quantity Circuit amps1 Poles2
1Select the closest value to the actual circuit amps.
2Select 3-poles for a 4-pole application as the amount of current flowing through the fourth pole (neutral current) should be negligible. If it is not negligible, select 4.
Available Fuse Types and Ratings
RK5 20 - 600 amps
Class J 20 - 600 amps
1-Time 20 - 600 amps
Class L 800 - 5000 amps
This calculator uses laboratory test data for Eaton Series C circuit breakers and Bussmann RK5, Class J, Class L and 1-Time fuses. Due to limited availability of product in all amperes ratings, only certain fuses types are available at a particular amp ratings. Please select from the table above. If you select a fuse type that is not available at that amp rating, the calculator will make an automatic substitution to an acceptable fuse type. For any current selection above 600 amps, a Class L fuse will be selected automatically. If a Class L fuse is selected for a rating below 800 amps, an RK5 fuse will be substituted.

Using the data above, and knowing the average quantity of greenhouse gases produced per each kWh of energy consumed, we can calculate the difference in greenhouse gas production between fuses and breakers. However we cannot determine operating cost savings without knowing the cost you pay for each unit of electrical power. These values are found from your most recent electrical bill. To insure you use the correct cost per kWh charge, make sure you sum every item that is based on kWh. These will include things like delivery charge, generation costs, stranded cost charge, transmission charge and any taxes associated with these items. Likewise, to compute the correct cost per kW, make sure you total any item that is priced per kW.

$/kWh $/kW Hrs/Yr of Operation3 Cost of Money4
$ per kWh $ per kW hours %
3If your system does not operate 24x7, change the "Hours of Operation" accordingly. (8760 hours = 1 year.)
4Savings received in future years are worth less than savings received today. The higher your cost of money, the more expensive it is to borrow, requiring a higher payback. Enter your cost of money to determine the cost you could justify spending based on your long term cost of money. If you are not the end receipient of this product and will receive no operating cost benefit from using either breakers or fuses, enter 0.

If you want to name this project (will appear on printout), enter that here:

Project Name

Different areas of the country product use differing combinations of power generation (hydro, nuclear, coal, etc.) and so produce differing quantities of greenhouse gases for the same electricity produced. Select your region from the list below:

EPA Region