ECN Forum Forums General Topics of the Trade General Discussion Area I believe that fuses are far superior than circuit breakers!

When I am called to repair a "bad breaker", which is a wiring problem or overload and not the breaker 99% of the time, I'll usually find that there's been someone that's tried repeatedly to reset the breaker (often against a dead short). This many times does damage the breaker. Fuses won't allow this type of problem, and the trouble can be fixed without additional damage being done to the electrical system.

With regards to installations with >10K fault currents:
The high interrupting capacity of fuses makes them much more attractive ($$$$$) than the use of high interrupting capacity circuit breakers.

I like fuses better...S

Thanks Scott:

The voice and opinion of a respected master electrician and seasoned mechanic is always welcomed, in addition to those who responded here and have real world experiences!

Yoa!

Don't hold your breath too long for AFCI Fuses may be just around the corner!!

Probably will be far less that those in the marketplace at the present time!

This was from Mike Holt's newsletter this morning.

This post has certainly generated alot of good comments. I have represented both the circuit breaker and fuse manufacturers in my past. I think the important thing to take away is that both fuses and circuit breakers can provide proper protection if proper maintenance and (testing for circuit breakers) are performed. Any device can be misapplied or improperly maintained. In addition, a fuse or circuit breaker may be better suited for a specific application. However, in my opinion there are less "concerns" with fuses compared to circuit breakers over the life cycle of the device.

With regards to the future of circuit breakers and fuses, I think we will see much improved features and protection from both devices.

With regards to arc flash protection, Ryan J appears to have picked a situation where a cirucit breaker can provide better arc flash protection. One caution here, what is the device type and ampere size...there really isn't enough information in his post to determine the application. With arc flash protection the, fault current, arcing fault current, type and size of the device has a great impact. There can be cases where a circuit breaker can be shown to provide better protection than a fuse, however, in general, I would argue that a fuse will provide better protection in the majority of cases. Another consideration can be the reliablity of operation. With circuit breakers you are relying on an expected response time that can only be confirmed with proper maintenance and testing.

We do have systems that prevent from insertig a too high rated fuse into a socket, but allow to use smaller ones. it's done by the diameter of the "diazed" fuse's front contact. the thicker, the more amps.
the socket has an interchangable insert or ring with the diameter for the right current.

we also have diazed fuse sockets that have a drawer where the fuse lies in. just pull it out of the module, old fuse out, new fuse in, and push it back in. works *almost* as fast as breaker resetting, 3ph fuse change in ~ 5-10 seconds, but difficult in the dark

One problem I have with the debate of fuses versus breakers is the final installation.

Fuses are tested and listed as open air devices. For proper application they must be installed in fuse holders and require an associated disconnecting means. Most 240V fusible devices are only rated at 10KA fault levels regardless of the rating of the installed fuse.

I have also seen many fusible switches which have not been exercised and so were unable to be opened when needed.

Finally, my experience has been that miniature molded case breakers (designed and built since the late 70s) are faster than fuses at clearing the low level faults encountered in residential applications. Fuses are faster at the higher level faults found in industrial settings. In fact the speed that these breakers operate at is part of the fuse-breaker coordination difficulties and why Bussmann no longer supports the up-over-and-down method of calculating fault levels.

Anyone priced fuses lately? Sometimes when troubleshooting an intermittent problem I can go through a box of fuses in a day. Some are in the $20-30 apiece. Sure would be cheaper to just reset the circuit breaker.
We have, just a guess, over 100 different types and sizes of fuses on campus and trying to keep them all in stock is nearly impossible. We had had equipment down for days waiting for a fuse that no one stocks. I've only had one occasion that a breaker failed to trip. But, I have also had fuses get so hot they charred the cardboard and didn't blow.

We have such panels in Britain. In fact, in many ranges the same panel will accept either breakers or fuse carriers, so there's nothing to stop you fitting a mixture of both.

Fuses often have the edge on interrupt ratings, and under our wiring rules can be used to "protect" a C/B which would otherwise have too low an interrupt rating. For example, the typical domestic C/B is rated 6kA interrupt, which could be exceeded in many locations close to a sub-station, however the cartridge fuse used in the main service will have a much higher rating and will blow should a C/B be unable to break a dead-short condition.

Joe,
Please let me digress for a second.
I'm of the school of thought that says, that a CB is a fixed, Non adjustable Protection device.
Made to trip at it's design current.
Usually, these are not tampered with by the H/O.
Most come in Magnetic(short-circuit) and Thermal Protection (Over-current), usually in the same device.
Take your average fuse, it can be changed at will, for a higher current Fusing element, whatever that may be.
Your Forum is proof of that, mate!.

JBD, are we talking about the same thing??


An example would be a Safety Switch