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Fuses and Circuit Breakers

fuses and circuit breakers Summary: All about fuses and circuit breakers and how they have evolved over the years and are used to protect your home electrical system.
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Fuses and Circuit Breakers for the Home Electrical System

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Fuses have been around for a long time, and there are still electrical systems today that are protected using certain types of fuses. Modern house wiring methods today do not include older fuses, in fact rewiring older homes and replacing the old fuse box is always recommended. Just like the older screw based fuses, electrical circuit breakers conveniently protect our home electrical wiring circuits and rarely wear out unlike the one time fuses that needed to be replaced when the circuit became overloaded.

The History of Fuses and Circuit Breakers

How fuses and circuit breakers can be helpful for your home.

screw based electrical fuses

The Edison Screw Based Fuse

A typical older home had an electrical panel with a few circuits that were protected by screw based fuses. Although this type of protection was reliable, the circuit integrity was often compromised by easily installing an oversized fuse which often lead to overheated circuit wiring and caused many house fires.

fuses with push button circuit breakers

Screw Based Circuit Breakers

One improvement in screw based fuses was this push button circuit breaker. This push button circuit breaker style fuse eliminated the need of having to replace a burnt out fuse. Other improvements were fuses that had a mechanical time delay that would prevent the fuse from blowing when the circuit had a sudden surge of electrical current due to larger devices such as a refrigerator.

screw based fuses and cartridge fuses

Electric Panel with Cartridge Fuses and Screw Base Fuses

The home electrical system began to see larger circuits which required more protection which was provided by cartridge fuses. These fuses have been used as the main electrical service protection being enclosed in a pull-out assembly that also served as a service or circuit disconnect. It was common to see two of these cartridge fuse disconnects, one for the main electrical service typically 60 amps 240 volts, and one 30 amp 240 volt circuit for a large circuit such as a well pump or a circuit to a barn or out building.

cartridge fuses for large electrical appliances

Cartridge Fuses for Large Electrical Circuits

Cartridge fuses are still used today for larger electrical circuits for equipment such as an air conditioner. Typically cartridge fuses are found on 240 volt circuits that require a disconnect to be close to the equipment enabling the power to be turned off while the equipment is being serviced.

modern day circuit breaker

Modern Day Circuit Breakers

For several years, the modern switch style circuit breaker has been used to protect all the electrical circuits for a modern home. These circuit breakers come in a wide range of amperage ratings and are used for 120 volt and 240 volt circuits. These circuits are know as single pole, double pole and three pole circuits which are found in commercial and industrial electrical services.

More about Fuses and Circuit Breakers

When upgrading a service panel from fuses to circuit breakers in residential housing are AFCI breakers required or just on new construction?

The inspectors in my county do not require me to do any other work when I get a permit to only upgrade the panel. There may be requirements in other areas which may address certain issues such as smoke detectors, gfci's or possibly afci's.Your best bet is to call the Building department in the Randolph area and ask them.

Its always a great idea to speak to the inspector who is assigned to your permit - they are usually very open to your questions and will usually help you out very nicely. A great attitude towards them will typically produce a great attitude back to you.When remodel work is taking place inside the home, then the building department will require those affected areas to be brought up to code.If you are planning to do additional work inside the home later on, make sure to think ahead and pre-wire for any circuits which will be needed. These can always be placed in the attic or crawl space in a junction box where they can be capped off and identified for future , the same back at the panel.

This question is based on a specific project. Ask The Electrician provides help for your electrical project: Ask Electrical Questions

Questions about Fuses and Circuit Breakers

Rod in Minnesota asks:
Can a Electric Fuse Socket Become Defective?

Our daughter has home built in the 60s with fused service panel. One fuse has started blowing ; when a new fuse is put in, it will not blow right away, it can go for hours sometimes without blowing. It is a 20- amp fuse circuit. On the circuit is a microwave and several regular outlets. The microwave has not been in use when the fuse blows. There is nothing excessive on the circuit and just normal use. Nothing out of the ordinary is being used when the fuse blows. I have checked that there are no foreign objects in any of the outlets. I have read that the fuse SOCKET can sometimes be defective, after decades of use. Do you think that is a possibility? The fuse socket contact looks a little pitted to me but I don’t know if enough to be a problem. I cleaned it with a toothbrush and electrical cleaner (sparingly) and let it dry well before reinserting fuse. It didn’t seem to help, the fuse still blew after a few hours. The fuse blows randomly (no set time or period of time). The panel is dry, I see no evidence of water intrusion. The fuse is Bussman SL 20 amp.

Dave’s Reply:
Time to Upgrade an Electrical Service Panel

An older fuse panel can produce several problems, especially as the electrical circuit load in the home increases. Over time the electrical contacts of the fuse box components can break down and wear out, and this can cause over heating and even blown fuses. Even though repairing the parts may help for a while, the time to upgrade the electrical service panel, and the home electrical circuits will always be the best solution.

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