Uprgrading Residential Electrical Service

"Does my electrical service have fuses or circuit breakers?"

It wasn’t until the 1960’s that circuit breakers became the standard for electrical service panels - before that all electrical panels contained screw and cartridge type fuses.

The way an electrical panel is made is the same regardless whether the panel uses fuses or circuit breakers. Fuses have taken a bad rap only because of the ease in which a fuse of one size can be replaced with a larger fuse. For example if a 15 amp fuse blows frequently a 20 amp fuse can be used to eliminate the nuisance of having to change the fuse so often. When a 20 amp fuse is inserted where a 15 amp was the current carrying capacity of the circuit is increased by 33% without any regard to the wire size. Remember that the fuse is rated according to the wire size - that is worth repeating a little louder - THE FUSE IS RATED ACCORDING TO THE WIRE SIZE. Because is it so easy to insert a 20 or even 30 amp fuse in to a 15 amp circuit, fuse panels have become an electrical hazard.

When a house is inspected for resale many insurance companies require a fuse panel to be replaced by a circuit breaker panel before the sale is complete. If the current service contains fuses it is probably worth the investment to upgrade the service from fuses to circuit breakers.

Upgrading the service to circuit breakers does not mean the amperage has to be increased. It is OK to change out a 100 amp fuse panel with a 100 amp circuit breaker panel. Just because the service is changing to circuit breakers does not mean the amperage coming in to the house must be increased to 200 amps.

This leads to the next question.

What size amperage is the existing service?

An electrical service is measured in amps with the standards being 100, 150 and 200 for a typical home. Amperage is like the size of the water pipe that feeds a residence - the bigger the pipe the more water that can be delivered. Don’t confuse service voltage with service amperage - service voltage comes in one variety 220/240, more on that later. If the home has a 100 amp service and there are no plans to add more electrical stuff (an addition, hot water heater, air conditioning, electrical heater and etc.) then why increase the size of the service. Unless you just want to keep up with Tim the tool man that lives next door who had his service increased to 200 amps - the present 100 amps that supplies the family with all the electrical comforts they need may be enough.

However, if an addition is going on or all the appliances are going electric, or electric heat or AC is being added, then the service increase may be needed. A calculation on the service demands for the household will have to be done to determine whether more amperage is needed - a master electrician can help with the calculation. For the skeptic that wants to calculate the service amps a good book about residential services or the NEC Handbook, a calculator and some patience will be needed.

If a circuit breaker keeps tripping will an increase in service stop that?

No. An increase in service amperage will not stop an existing breaker or fuse from tripping. The increase in an electrical service will have no impact on existing circuitry. Any circuit breaker or fuse that trips does so because the circuit amperage exceeds the circuit breaker or fuse size.

So there are two reasons to upgrade a service:

• Changing from fuses to a circuit breaker panel.
• Increasing the electrical load.

Increasing the electrical load required by adding on or installing higher amperage appliances MAY require a service upgrade - but do the calculations first.