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Circuit Breaker or Fuse Box?

on November 19, 2015

It used to be that all houses, buildings, and electrical
equipment were protected by a fuse box.
Many systems still are (your car, for example, uses a fuse box for its
own electrical system).  

As an electrical
protection device, fuses are efficient and simple tools but as technology has
advanced, so has our security against danger and damage.  Breaker boxes have almost universally
replaced fuse boxes in homes across America.
But some still exist in homes.  Do
you need to upgrade to a breaker box.  We
can help if you feel you should, but we can also help you figure out if it is
an upgrade your home actually needs.


A fuse works by being the weakest link on an electrical
circuit.  Every device and connection
should be rated for the current that can pass through the fuse.  A 20-Amp fuse will open the circuit as soon
as the rating is exceeded.  If any device
on that circuit cannot handle a 20-Amp current, the fuse should be lower to
meet the limitations of the circuit.
Mechanically, a strip of metal inside the fuse carries the current.  When current reaches the fuse’s rating, that
metallic strip vaporizes, permanently removing that fuse from service and
opening the circuit to prevent damage.
This happens extremely fast, and these fuses are very sensitive to
overload conditions. As a fail-safe system, they are highly effective.

Breakers, on the other hand, use a more complicated
system.  Metal expands as it heats, so a
breaker is actually composed of two different strips of metals sandwiched
together (the bi-metallic strip that’s mentioned so often).  As current increases, the metal conductor
inside a breaker circuit heats up, causing these metals to expand.  Since the two metals expand at different
rates, the strip bends.  Once the strip
bends far enough (the metal has grown hot enough due to the load being placed
on it) the breaker trips and the circuit is shut off.  A circuit breaker is effective and re-usable,
but not quite as fast-acting as a fuse.

Circuit Breakers

  • Re-usable
  • Can double as GFCI or AFCI breakers
  • Easily adaptable for new circuits
  • When installed professionally, unlikely to have
    the wrong amperage rating
  • Slower response times
  • Sensitive to vibrations


  • Greater sensitivity and faster acting
  • Inexpensive
  • Must be replaced every time
  • Chance of replacing with incorrect fuse
  • Likely to be an older system

Properly installed, fuses are
just as viable for protecting your home as a circuit breaker.  Your main concern should be having spare
fuses on hand in the event of an emergency and having the fuse box clearly
marked for the right kind of fuse.  A
circuit breaker is easier to use, but unless you’re experiencing regular blown
fuses, a full upgrade may not be necessary.

If you’re having issues with repeat breaker trips or blown
fuses, call Mainstream Electric for help.
We have the experience and tools to find the problem and get your
circuits back to stable operation.
Regular circuit overloads are often a sign of bigger problems and should
be dealt with before they become an issue.

Choose Smart! Call the Company with Heart! 866-411-ZAPP (9277)

For more information on home and business electrical inspections, visit Mainstream Electric online.

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