Are breakers safer than fuses?

Thirty years I have owned this house and I just discovered that two of the receptacles in my 1951 house are not turned off by removing any of the fuses. One fuse appears to not have any effect on any part of the electrical system. I suspect the original owner did something to bypass that fuse and will have an electrician investigate. If it is something that can simply be rewired, that will be great. However, I seem to recall that circuit breakers are safer than fusses because they will trip long before a fuse would blow. Is that true enough that it is worth the cost of replacing the fuses with a new breaker box even if not necessary for the repair? Also, the 100-amp fuse box is not a sub-panel o a 200-amp circuit breaker box I had installed when we first moved in. If I replace the fuses with circuit breakers, does that mean replacing the cable between the 200 and 100 amp boxes so that the new one will have an equipment ground? Thanks.

I am not a pro, and in my opinion modern circuit breakers are very safe and what you should have. That is not to say fuses are not safe. An argument can be made fuses are even safer because when a fuse blows the gap is melted open and current is totally stopped. In the case of breakers being a mechanical switch with contacts to allow resetting there is always some chance of the switch failing shut or in the case of a dead short circuit the inrush current can be enough to weld the contacts shut. Circuit breakers work with current flow heating and a gradual high above rating is what trips them best.



The thing with fuse panels is if you have one it is quite old for starters and with screw in fuses they all had the same screw base and often time people went to a larger fuse or stuck a penny behind it when in a pinch and didn’t have the right fuse. If you have found some circuits that don’t open when fuses are pulled that needs to be fixed right away and most electricians wont want to mess with fixing it as it will be quicker to replace it with a breaker box.



Many homes were wired in the 40s and 50s with 60a fuse panels. Then the 60s and 70s rolled around and they added 30a switch fuse panels for other things they wanted. I have seen them where they brought a second feed in from the meter to power more stuff. None of this stuff is exactly all that great and there are millions of homes with it built back before electrification came along or built when fuses were the thing. At one time 60a seemed like more than enough for a house. Now 200a is becoming the norm.



My suggestion would be to get a pro in and at least upgrade the front end. Sometimes they use the old panel location as a terminal to tie the old to the new. Then if you wanted to take your time and figure out what you wanted to rewire that could maybe be DIY.

My opinion also is that breakers are safer than fuses. And even if they were not I would take this time to update your system since it is so old. The electrician may find something that really needs attention.

If you are in a single family house then there has to be some type of overcurrent device servicing that circuit you say you can not shut off. I am sure you would know if there is another panel somewhere else in the house.
As far as your present system and upgrading/updating to a breaker panel. The electrician will get a permit and their work inspected. The electrician will know what has to be done in the way of grounding etc to meet today's code of the NEC plus any local codes in your area that the electrician must follow. Without knowing all of the details of your present system it is difficult for us to tell you all that must be done.
Get yourself 3 quotes by licensed electricians. Let them itemize what needs to be done. Discuss your needs with each of them. Don't go with the lowest quote automatically. Go with the quote from the electrician that educates you and explains what needs to be done and why. When ever I did an upgrade or update I always reviewed this information with the home owner in detail explaining what I was going to do and why.

Fuses are often used on water well pumps as a final protection against lightning strikes to protect the well pump when lightning strikes the metal well casing. Breakers have largely replaced fuses in other applications in residential and commercial wiring. I can't speak to industrial wiring. A house built in 1951 would have Romex wiring, and not knob and tube. It would likely not have a ground wire. The outer sheath tends to be a woven cloth, but the individual conductor insulation is pretty robust. It wasn't rubber at this point, but some sort of plastic. Given the wire is generally not exposed to sunlight it holds up pretty well.

I have never worked on a fuse box but I would assume that one can remove the front panel and see if any wires are connected w/o fuses.

Eddie_T said:

I have never worked on a fuse box but I would assume that one can remove the front panel and see if any wires are connected w/o fuses.

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Yes you can get behind the panel and see what is going on just like in a modern breaker panel.



Here is a pretty good explanation and in it he shows what is behind the panel.

Thanks to all for your replies, and, ...

Dang. About the worst typo I could have made in my post. Where I said "the 100-amp fuse box is not a sub-panel o a 200-amp circuit breaker box ..." it should have said it is NOW a sub-panel. Just one letter, but a critical one.

Did you say what that sub panel is feeding?

To answer your 2nd question you may not have to upsize the feeder BUT you probably will, at the very least, run new NM to the new panel. Be a fun weekend project.

Maybe off topic but when my parents house was wired for 240V to accommodate an electric range an old knife switch 30A box with two fuses was replaced with a "modern" 60A main-range, 2x4 fuse box. The range had a receptacle on it which was later used for a toaster. It just occurred to me that the outlet was fused at the same amperage as the range. That's OK though as the fuse is to protect the wiring and the receptacle was probably wired with the same high temp wire as the burners. However a toaster short could have resulted in a 60A arc flash or a fire.

BTW screw in circuit breakers to replace fuses are available.

Hamberg said:

Did you say what that sub panel is feeding?

To answer your 2nd question you may not have to upsize the feeder BUT you probably will, at the very least, run new NM to the new panel. Be a fun weekend project.

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The sub-panel was the original main so it feeds all of the original house circuits.

There is a part of me that wants to do this DIY, and 20 years ago I would have, but now - I will leave it to a pro.

Eddie_T said:

BTW screw in circuit breakers to replace fuses are available.

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I have never heard of screw in breakers. The only reason to replace the fuses with a breaker box (that I know of now - inspection by electrician might reveal more reasons) is my understanding that breakers are more sensitive (i.e. will trip faster when a fault occurs) than fuses. Do you know if that is also true of screw in breakers?

tomtheelder2020 said:

I have never heard of screw in breakers. The only reason to replace the fuses with a breaker box (that I know of now - inspection by electrician might reveal more reasons) is my understanding that breakers are more sensitive (i.e. will trip faster when a fault occurs) than fuses. Do you know if that is also true of screw in breakers?

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I don't really know anything about them. They appear to be button reset so to kill a circuit I think one would have to be unscrewed as with a fuse.

I can say from personal experience the new Arc Fault/GFCI breakers are much more sensitive than regular breakers and definitely fuses. Fuses and regular breakers protect the wires from overloading. Arc Fault and GFCI protect the wire and the users. I had a heck of time finding the issue that was tripping a combo breaker on my new lighting circuit in my basement project. A regular breaker was happy with no issues. The arc fault would trip immediately. I finally tracked it down through the process of elimination.

Sparky617 said:

... A regular breaker was happy with no issues. The arc fault would trip immediately. I finally tracked it down through the process of elimination.

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I looked into the possibility of combo breakers but read a couple of places that they are not a good match for older wiring because of constant nuisance trips.

Actually I don't recall an overcurrent breaker ever tripping. My GFCI plug on my PTHP tripped and wouldn't reset. I opened the unit, disconnected the green wire and the problem went away (I did check for stray voltage after disconnecting).

tomtheelder2020 said:

I looked into the possibility of combo breakers but read a couple of places that they are not a good match for older wiring because of constant nuisance trips.

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I had to install combo breakers for my basement project due to code changes. I don't have to retro-fit the rest of my house with them though. I could see them being a royal PITA on old wiring. They sense any imbalance in the hot and neutral and will trip. If you have a nick in your neutral wire they'll trip. Don't ask me how I know this. I can't see them working with knob and tube, and might be an issue on early Romex without a ground. But I'm not sure on that last part.

First, breakers are far more effective than old style fuses. Their other advantage is they can be re-set. Fuses just burn out.
Second, you need a proper circuit tracer to understand what is going on. I would start with a model that allows you to see if any fuse is connected. They are not expensive and easy to use. Klein Tools Digital Circuit Breaker Finder with GFCI Outlet Tester (ET310) ET310 - The Home Depot

You have many posts here with great advice!
The only thing I wish to add is a saying we had at work: "Fuses Never Fail".

As a retired, 45+ year industrial electrician who worked on voltages from less than a volt to over 300,000 volts routinely, I have seen plenty of circuit breakers that did not open on time, if at all. Federal Pacific Stab-Lok were a prime example.

Look up on an electrical pole at the transformers or correction capacitors. Those tubes at an angle are fuses, not breakers. Why? Ice, corrosion, condensation, age, seized points won't cause the fuse not to open, as it could on a circuit breaker. There is nothing mechanical to get stuck.

Another nice thing about the glass, screw-in Plug fuses is that you can look at the glass and tell if it opened from over amperage or from a short circuit. If the window is covered with soot, it was a short circuit fault. If it is clear, it was an over amperage fault.

So, don't be afraid of fuses as long as you use the correct voltage and amperage. (New screw-shell type fuse panels are made for Type S fuses- Each base is sized for the amperage. Adapters are available for older panels.)

Also, don't be afraid of circuit breakers in your house. Ask the residential electricians here for recommendations. (My only one is that if your load center is in a damp location, such as a basement, I recommend bolt-on breakers. The screw that seals the tab to the bus bar keeps moisture out better than a snap-in breaker for no corrosion and loosening of the connection.)

I hope this helps put your mind at ease with fuses- and circuit breakers.
Paul

PJB12 said:

I hope this helps put your mind at ease with fuses- and circuit breakers.
Paul

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Paul, thanks for adding to the discussion. As an update, it appears the laundry room receptacle not controlled by a fuse has separate circuits for the upper and lower parts. That means I actually have seven circuits coming from a six fuse box, two of them bypassing the fuses. That, the location of the box, and that breakers will be looked on more favorably (rightly or not) when I sell the house, all led to the decision to turn the fuse box into a junction box and put all 7 of those circuits onto breakers in the main panel.

Your plan sounds really good. Remember to fasten the door of the old panel closed when it becomes a junction box.

Keep in mind that if you run out of breaker spaces in the main panel, tandem breakers are available for many panels. A tandem is two circuit breakers that use one breaker space. Sometimes they are called "Piggyback". You can get both halves the same amperage, or different amperages. (Photo attached)

Don't share a neutral with a tandem because the amperage will be cumulative since the breakers on the same phase. (Separate ones for each half of the breaker.)

Enjoy Your Project!
Paul