What are the safety concerns of not upgrading from fuses to breaker panel?

Question

This is a follow up question to one asked earlier:

http://ca.answers.yahoo.com/question/index;_ylt=AiYeL8RAIEsnFVgmU2FjL6_AFQx.?qid=20070102154538AAjNJ80


Many people said that there are satefy concerns, even life threatening, but didn't elaborate. Others, on the other hand, said that there is no point in switching to breaker panels.

Besides the convenience of breaker panels, can you elaborate what are the safety concerns to upgrade from fuses to circuit breaker? ... or is this a myth?

Thanks

House: 100 amps, all copper, fuses, 55 yro.

Answer 1

Ok, it's specifically related to RCD (Residual Current Devices), rather than generic circuit breakers. A circuit breaker is basically a fuse that can be reset.

With a fuse or a circuit breaker, if the current drain is over a certain limit, it cuts power. Unfortunately, this limit (and the time taken to cut power) can easily be high enough to kill you if you're part of the circuit (eg touching a live cable).

with an RCD, it basically compares the flow in the phase and neutral wires, rather than just the total power drain. If there is a difference (general standard is 30mA, or 0.03 amps), it realises something's up (something not meant to be in the circuit is causing a drain, like you poking a screwdriver somewhere by mistake), and cuts the power, even if the drain wasn't that big. The cutoff time is about half a second, and this is considered a small enough amount of power and time not to kill you.

It's a little more complex than that, but those are the basics.

Answer 2

If all is working properly, no need to change. Breakers are newer technology and are safer, but as long as things are working OK, no real reason to change. When you change a fuse, make sure to replace with an "S" type though. This will prevent installation of an improper sized fuse. Resale value may be a bit lower, no other real reason tho.

Answer 3

Circuit breakers ar not safer than fuses, they both do the same thing. If you have fuses though, your entire panel and service entrance is old and could be substandard. Updateding your service entrance is always considered a safety improvment.