I have a four fuse panel box. I blew a fuse. When I went to replace I noticed 3 15 amp fuses and 1 20 amp fuse. How do I know what size fuse is safe? House built in 1948. I have lived here since 1991 and never blown a fuse. Nothing is labled.

What are S type fuses? Is this the type I need?

...and shunts -- oh, my!

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It is what it is.

If the house has never been re-wired, they're probably all 15 amp lines. however, i think that a 15 amp won't fit in a 20 amp socket etc. i may be wrong.

Well... people used to use pennies in place of fuses. They are much easier to find after the fire.

S pennies, I would assume, are made at the San Francisco mint.

I haven't dealt with a fuse box in 20 years.

If I remember correctly, the 15-amp fuses are a different color, green, I think, than the 20 amp, orange or brown. I think the 15-amp are smaller than the 20-amp as well.

I would take the blown out fuse to the hardware store and ask for advice.

deco, always safe is to replace like with like -- e.g., if a 15A blows, replace with same exact thing.

In my apt, I have two 15A and two 20A. They each have different size bases/threads. Unfortunately, my apt is only served by two circuits, and I blow my fuses fairly regularly -- simply put, the wiring which existed in the 50's is not satisfactory for the 2000's-- the wattage of everything has simply gone up, and I have tons of computer equipment, an air conditioner, etc. I don't think there is much that can be done about it, other than getting the house new wiring-- and my landlord is not likely to do that.

S-type -- I believe refers to the fact of the fuse having a thread which supposedly prevents you using a fuse of the wrong rating.

The old style of fuses were all the same physical size and yes a penney would fit under a dead fuse making for a fire waiting to happen. Most of these boxes were adapted at some point to take the later all ceramic fuses that were diff. sizes depending on amperage rating. The "adapter" was a screw in base that was more or less permanantely fixed once screwed in. They way the make connection a penney of dime or other flat disk would not "jump" across the connections. Most of 4 fuse houses had a 60 amp service which would allow for 4 15's only.

Many times the service entry cable has replaced with a heavier gauge cable allowing for maybe 90 amps, Look at the cable going from the meter to the fuse box and see what the gauge rating is and the condition of the sheathing.

The house should be "heavied up" which with a new 200 amp panel (which is minimum code now in many places ) installed was around $1200. 8 years ago or so (depending on the area).

Didn't archie bunker try the ol' penny trick?

Just replaced the 15 amp fuse with a 15. Took a look at the others.

On the left side of the box is a pull out handle that says MAIN and under it are 2 fuses. If you take them out and use a flashlight you can read on the socket base use 7 to 15 in the left one. On the right one was my 20 fuse and the base says use a 20. I tried to put a 15 in it and it was too tight by a smidgen.


On the right of the box is pull out handle and it says Range.
Under it are 2 fuses that also say use 7 to 15 in the base.

The pull out handles each house some ancient looking tube fuses I guess.

The air conditoner and washer and dryer are not affected by this box. They have their own panel in the basement.

S rated fuses are a time delay type fuse. Designed to have a heavy load like a motor be able to start without blowing the fast acting fuse (a normal fuse).

Replace it with the same one you pulled out.

I was an electrician for 10+ years - and can say you should really think about having the fusebox replaced with breakers. Peace of mind. :>)

I've seen too many fuse panels that have either burned up from being WAY overloaded, or ones that DID have a penny behind it (and the melted / charred wires).

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Good Luck!
Jamie Dresser
Other World Computing

where do they put the pennies

Behind the fuse, between the bus and the contact on the fuse. Keeps the fuse from blowing no matter what.

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Good Luck!
Jamie Dresser
Other World Computing

You shouldn't have told her that. :}

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Roswell, GA (Atlanta suburb)

man, my garage carries more load than your house! 200 amp house, and 60 to the garage.

I just wanted to make sure there were NO pennies in my fuse box.

I have a fuse box in my house. The past owners had yanked the 15 amp fuses and replaced them with 20s...a major fire hazard. The bases of both were exactly the same size. I pulled them out and replaced them with 15 amp breakers...you can now buy miniature breakers that screw into the fuse base. I highly recommend this...never again replace a fuse or worry about what size fuse to install. They cost more than fuses but the peace of mind is worth it.

Also, I'm a little unclear on where it is on your fusebox that it is labelled 20 amp. There are very few circuits on older houses that have wire that will handle 20 amps. What exactly is running off that circuit?



Edited 1 time(s). Last edit at 12/14/2005 01:22AM by davester.

I had an old apt once that had fuses and someone had stuck in a 30 where the 15 should've been. whenever I ran my AC the power cord to the unit got so hot it melted the plastic insulation!!!!

davester, typically the 20 amp ones are for large appliances, e.g., washer/dryer, refrigerator, etc. Like I said I have two of those, which never seem to blow, whereas the 15 ones blow like crazy... I just now had another one go on me. Probably it's because I'm using a small electric heater and a microwave on the same circuit...

The Breaker has sockets that the fuses screw into.

At the base wall inside the fuse socket is lettering around the contact (that the fuse would touch) Lettering is very tiny and goes in a circle around the contact point.

The 15 porcelain fuse does not screw all the way in the labled 20 socket even though they appear to be the same size, they must not be.

I have a Frank Adams fuse box.