Are fuses safer than breakers?

[ericsarratt]

1) I had an electrician tell me that for residential panels the old bussmann glass fuses were safer than circuit breakers.

He said that sometimes a breaker won't trip whereas a fuse will open the circuit.

I do realize that people put pennies behind fuses or over size a fuse that keeps blowing in an attempt to fix the problem and that this makes fuses unsafe.

Your thoughts.

2) Is it possible to still buy the old bussman glass fuse boxes?

3) My hunch is the NEC (about to take the course) no longer accepts these for residential service?

 

[LarryFine]

In that regard, yes, fuses are safer; it's much more unlikely for a fuse to fail to open.

One disadvantage is non-simultaneous tripping.

Yes, plug fuses are still available, and I'm not aware of any code prohibition of their use.

 

[ericsarratt]

One disadvantage is non-simultaneous tripping.

What do you mean by this?

 

[ericsarratt]

Yes, plug fuses are still available, and I'm not aware of any code prohibition of their use.

But are the boxes they plug into still available from manufacturers? I looked and could not find them.

 

[HEYDOG]

What do you mean by this?

If you have a 240 volt circuit with a fuse for each line and only one fuse opens the other side is still hot and could cause feedback thru the side the fuse blew on. One side would still be hot regardless!

 

[LarryFine]

If you have a 240 volt circuit with a fuse for each line and only one fuse opens the other side is still hot and could cause feedback thru the side the fuse blew on. One side would still be hot regardless!

What he said.

 

[__dan]

The screw in old glass fuses, if people blew a fuse they would rarely be expected to change it to the proper size. They were color coded, 15 - blue, 20 - orange, 30 - green. you might see a blue or orange if they were still original equipment. But if they were blowing fuses, a panel full of green was pretty common to find.

Properly sized fuses are much better than breakers. Especially in the larger size old breakers compared to old current limiting fuses. Big breaker let through is a lot more, slower to operate. If it is protecting me, I would much rather see fuses.

The modern electronic trip breakers are very good

 

[jim dungar]

Fuseable panels, for residences, fell out of favor almost 60 years ago, which is just about as long as they were in common use.

I have never seen any proof they were 'safer' than breakers. There is little in the world that is 99.999 sure, so based on the shear number of residential breakers sold over the past 70 years it is no wonder you can find examples of failure to open/trip.

 

[PaulMmn]

They tried to overcome the 'up-sizing' with the inserts that only accepted the 'proper' size fuses.

 

[ericsarratt]

The screw in old glass fuses, if people blew a fuse they would rarely be expected to change it to the proper size. They were color coded, 15 - blue, 20 - orange, 30 - green. you might see a blue or orange if they were still original equipment. But if they were blowing fuses, a panel full of green was pretty common to find.

Properly sized fuses are much better than breakers. Especially in the larger size old breakers compared to old current limiting fuses. Big breaker let through is a lot more, slower to operate. If it is protecting me, I would much rather see fuses.

The modern electronic trip breakers are very good

By modern electronic trip do you mean:

1) AFI?

2) GFI?

3) The new white Leviton "smart" circuit breakers (it didn't say electronic trip)?

4) The electronic trip ones I saw that seemed to be for industry and commercial applications?

 

[Sea Nile]

Not a lot can go wrong with a fuse. It's solid state and simple.

Fuses, however, depend on the home owner having common sense. Not using a larger size because it keeps blowing, ect.

Let's face it, modern breakers make everything dummy proof. And in removing the dummy from the equation I would say breakers are safer.

Plus there is no GFCI or AF fuse

 

[jim dungar]

But are the boxes they plug into still available from manufacturers? I looked and could not find them.

To my knowledge no major manufacturer makes a panel board that uses these 'plug' fuses.
You may be able to find disconnect switches that use them, they were common on boiler and furnace applications.

 

[ron]

To my knowledge no major manufacturer makes a panel board that uses these 'plug' fuses.
You may be able to find disconnect switches that use them, they were common on boiler and furnace applications.

I'm not sure of the "plug" fuses and how they relate to the Bussmann CUBEFuse.

https://www.eaton.com/us/en-us/catalog/fuses-and-fuse-holders/bussmann-series-qscp.html

 

[jim dungar]

I'm not sure of the "plug" fuses and how they relate to the Bussmann CUBEFuse.

https://www.eaton.com/us/en-us/catalog/fuses-and-fuse-holders/bussmann-series-qscp.html

The cube fuse is a relatively new design. It bears no resemblance to the OP screw-in style fuse.

 

[petersonra]

Not a lot can go wrong with a fuse. It's solid state and simple.

The problem with fuses is that when they go, you have to replace them and often the exact same rating of fuse is not readily available. This leads to people doing all kinds of unsafe things because they can't find a replacement real quick.

 

[jim dungar]

The problem with fuses is that when they go, you have to replace them and often the exact same rating of fuse is not readily available. This leads to people doing all kinds of unsafe things because they can't find a replacement real quick.

Another problem with screw in fuses is the lack of simple on off switching. Removing the fuse exposes energized parts. I consider both of these to be more of a concern than a statically extremely low probability of failure to trip.

 

[David Castor]

Molded-case breakers and breaker panels are DEAD-FRONT. This was one big reason why they won out over fuses for most applications, especially residential.

I'd be cautious of any more safety advice that this guy might offer up.

 

[drcampbell]

The problem with fuses is that when they go, you have to replace them and often the exact same rating of fuse is not readily available. This leads to people doing all kinds of unsafe things because they can't find a replacement real quick.

Canadians solved this problem by making fuses with larger button diameters correlating with larger current ratings, and rejection discs in the fuseboxes. You can screw in a smaller fuse but not a larger one. The rejection discs might make the fuseholders finger-safe, and they do render a penny in the fusebox ineffective.

(full disclosure: I have seen them in the field but do not know how current this information is; they might have abandoned the practice a long time ago)

 

[garbo]

In that regard, yes, fuses are safer; it's much more unlikely for a fuse to fail to open.

One disadvantage is non-simultaneous tripping.

Yes, plug fuses are still available, and I'm not aware of any code prohibition of their use.

Plug fuses can only be used in existing locations. While attending a great Vo Tech school our shop teacher asked what would clear a dead short faster a fuse or circuit breaker. First we tried a 15 amp fuse & circuit breaker in series and the fuse always opened up. Used 3 different company breakers. Then we used a 15 amp circuit breaker in series with several different plug in & bolt on 20 amp circuit breakers and the fuses always cleared first. For motors I always preferred quality time delay fuses with a high KIA rating.

 

[jim dungar]

Plug fuses can only be used in existing locations. While attending a great Vo Tech school our shop teacher asked what would clear a dead short faster a fuse or circuit breaker. First we tried a 15 amp fuse & circuit breaker in series and the fuse always opened up. Used 3 different company breakers. Then we used a 15 amp circuit breaker in series with several different plug in & bolt on 20 amp circuit breakers and the fuses always cleared first. For motors I always preferred quality time delay fuses with a high KIA rating.

I can set up a home test that can prove just about any scenario I want.
The reason that series ratings, of fuses protecting breakers, must be 'tested' is that some breakers can definitely open and clear some faults before some fuses can. It can take less than 50' of #12AWG to prevent both fuses and breakers from entering the instantaneous portion of their trip curves.


Edited: typos corrected after having been quoted.