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Changing fuse-Old Box-Do I turn the power off by pulling out boxes?

Changing fuse-Old Box-Do I turn the power off by pulling out boxes?

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  #1  
Old 12-23-10, 04:16 PM
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Changing fuse-Old Box-Do I turn the power off by pulling out boxes?

I live in an older home. It has a fuse box with the screw in type fuses.
I see which fuse burnt out. There are two boxes above the fuses which I think pull out to shut off the power. Do I just pull them out? Do I need to turn the power off to change the fuse? I know which one is burnt out..
Any assistance is appreciated.
 
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  #2  
Old 12-23-10, 04:27 PM
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You pull the one marked: ''MAIN'' or ''APPLIANCES AND LIGHTS'' or something similar.
 
  #3  
Old 12-23-10, 04:40 PM
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Don't pull the main, you'll be in the dark. Since you know which appliances/lights are out, unplug them or turn them off. That will take the load off the fuse. Unscrew the affected fuse and replace it with one of the same size. Do you know if you have Edison base fuses, or fusetrons?
 
  #4  
Old 12-23-10, 04:53 PM
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Originally Posted by chandler View Post
Don't pull the main, you'll be in the dark.
If you feel more comfortable pulling the main, pull it! Just do not forget a flashlight!

Originally Posted by chandler View Post
Do you know if you have Edison base fuses, or fusetrons?
You will need an identical fuse. Do not go any size larger than was there.
 
  #5  
Old 12-23-10, 04:56 PM
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I think it is only the bathroom that is affected.
I don't see that any other circuit is affected.
The fuse that is blown is right below those main "boxes"
I think it is a 30 AMP fuse.

I want to be as safe as possible. Actually I just went down and read the one again..the one on the right says "pull to renew fuses" ? It may say remove. It's hard to read..so I think the one on the right is the only one I need to pull?
I don't care if I go dark temporarily. I have a flashlight and will open up the garage and turn the headlights on.
 
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Old 12-23-10, 05:34 PM
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I think it is a 30 AMP fuse.
Stop. It should in all likelihood be 15a. Do not replace with a fuse larger then 15a unless ther wiring is larger then #14.
 
  #7  
Old 12-23-10, 05:55 PM
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I was going to check when I pulled it out..I have 15 amp, 20 am, 25 am, and a 30 AMP fuse ready to go..Do I need to turn the power off to pull the bad one?
I am just totally confused on that.
 
  #8  
Old 12-23-10, 06:06 PM
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No, you don't need to pull the mains to replace a single branch fuse. Use common sense when working around the fuse panel (ensure the ground is dry, don't stick your finger in any open fuse sockets, etc)

As others have mentioned - the more potentially dangerous situation is that it sounds like that circuit (and possibly then others) have been overfused. The fuses are there to protect the wiring in your house so that if you plug in too many lights/appliances than the wire in the walls can carry safely, the fuse blows. In older houses and older fuse panels, often people run into a problem where too many devices on a circuit blows a fuse a couple times, so they simply screw in a larger fuse. Now the wire may be forced to carry more current than they can handle - which isn't a good thing.

Based on the little you've said, I think it's time for a review of your fuse panel. Either you need to learn enough to check it all out (and the fine folks here I'm sure will help) or you should call in an electrician to check it all out and install fusetrons.

Good luck!
 
  #9  
Old 12-23-10, 06:30 PM
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I don't mean to beat the dead horse..
The fuse that went out was the one that is directly below those main "boxes"..
There are four lower on the box that are just fine.
Are the ones right below those pull out boxes "main" ones or branch ones?
 
  #10  
Old 12-23-10, 07:12 PM
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Originally Posted by pittguy578 View Post
I don't mean to beat the dead horse..
The fuse that went out was the one that is directly below those main "boxes"..
There are four lower on the box that are just fine.
Are the ones right below those pull out boxes "main" ones or branch ones?
Assuming this is a typical old fuse box and you are looking at screw-in fuses, they are branch circuit fuses. The two boxes you refer to are "Fusible Pullouts". You probably have two of them side by side. The left one probably conatains two 60 amp cartridge fuses which are the MAIN for the screw-in fuses. The "Fusible Pullout" on the right is most likely marked "Range" and is for a large appliance circuit such as an electric range and also has 50 or 60 amp cartridge fuses. Many times the Range Pullout is used to power a water heater or subpanel somewhere else in the house if you have a gas range. As Ray stated, unless you can verify the wire size is larger than #14 gauge, don't put in a fuse larger than 15 amps. If the branch circuit screw-in fuses have porcelain threads, they are Buss Fustats and won't allow you to put in a larger fuse, but I suspect you have typical edison base fuses with the same metal threads as a light bulb, they are more common in older fuse boxes. You don't need to pull the main to change a fuse.
 

Last edited by CasualJoe; 12-23-10 at 07:16 PM. Reason: added info
  #11  
Old 12-23-10, 07:15 PM
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Are the ones right below those pull out boxes "main" ones or branch ones?
They are branch ones. Main fuses will almost always be cartridge fuses. That is what is in the boxes.

15 amp, 20 am, 25 am, and a 30 AMP fuse ready to go
You would never use a fuse larger then 20a on a 120v circuit but it is almost certainly a 15a circuit. As I said earlier unless you can verify #12 or larger to every outlet on the circuit never use any fuse larger then 15a. Did you buy time delay (AKA slow blow) fuses? They are generally best in case there are any motor loads.

If the old fuse was 30a and a 15a fuse won't hold the circuit you are going to need to do some rewiring. You can not safely increase the fuse size.
 
  #12  
Old 12-23-10, 08:37 PM
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Ok..I am going to do it here shortly..I will let you guys know how it turns out.
I am going to wear a pair of heavy rubber gloves just in case.

I don't think it is any "long term" problem. Our furnace went out this past week, and we had to use more electrical heaters in the meantime to heat the house.
I think that may have caused the problem. The new furnace is in now so there should not be any more blowouts..

Thanks for all of your help.

Jim
 
  #13  
Old 12-23-10, 09:25 PM
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we had to use more electrical heaters in the meantime to heat the house.
A 15 amp fuse will at best support only one electric heater on high but only if there is nothing else on the circuit. Otherwise it is Vegas odds for each additional load, even a light bulb.

You mentioned the blown fuse might be 30amps. If any of the others are better increase your fire insurance or change them to 15a.
 
  #14  
Old 12-23-10, 09:46 PM
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Ray, it sounds like you don't think there should be any fuses above 15 amps in an old fuse box. I have no experience w/ fuse boxes, but couldn't there be 20 and 30 amp (and even higher) fuses for appliances in these old boxes?

i think I need a history lesson, if you got time
 
  #15  
Old 12-24-10, 05:32 AM
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Till Ray logs on....Older houses were almost all wired with cloth covered 14 gauge wire. Occasionally and on certain circuits they would use 12 gauge. But not for general lighting and receptacles (not the rule). So in most instances 15 amp fuses were the norm with an occasional 20 amp to the refrigerator and other "known" high pulls.
Here locally we cannot replace fuses with fuses. We have to determine the wire size and insert an S-type fuse assembly with the specific base for that size. The base has a little wire that sticks out at a ccw angle and prevents its removal. That way ONLY the proper size S-type fuse can be inserted in that hole. Edison based fuses should have been outlawed eons ago.
Oh, back when this wiring was taking place, they relegated the buss type fuses in the "boxes" mentioned to handle everything above 20 amps.
 
  #16  
Old 12-24-10, 06:30 AM
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I have some 10awg K&T in my basement, as well as other houses locally. Built in 1897.
 
  #17  
Old 12-24-10, 06:42 AM
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Which code book covered that? The question was whether or not the glass fuses controlled the 10 gauge or the buss fuses? Most likely the buss fuses in the pull outs.
 
  #18  
Old 12-24-10, 07:44 AM
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Originally Posted by tacticaltal View Post
Ray, it sounds like you don't think there should be any fuses above 15 amps in an old fuse box.
You note I said unless the wiring to every thing is greater then #14. I said that more then once. If the wiring is #12 to every outlet (outlet as defined by the NEC) then yes you could use a 20a fuse. As Chandler said though those were special purpose circuits usually. The OP has stated he believes it is bathroom only. It is doubtful the bathroom was wired with larger then #14. I'm not there. The op has not mentioned wire size so I give the safest answer.

It is my understanding modern code does not permit OCPDs larger then 20a on 120v general purpose residential branch circuits regardless of wire size. If a very old 120v GPBS was wired with #10 would 30a fuse be permissible under grandfathering I can't say for sure. I wouldn't though use a 30a fuse.
 

Last edited by ray2047; 12-24-10 at 10:33 AM.
  #19  
Old 12-24-10, 09:25 AM
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Until you find out the wire size, a 15A fuse is best. I saw minibreakers that take the place of an edison-based fuses at lowe's, and true value.
 
  #20  
Old 12-25-10, 11:45 PM
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Changing a blown screw in type fuse is not a big deal. turn it counter clockwise to unscrew. Shine a flashlight into the socket and see if there is a sticker on the inside that tells the amp rating. To replace the fuse put the new run in and turn it clockwise. I had fuses at my other house and replaced them all the time.
 
  #21  
Old 12-26-10, 07:40 AM
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If you leave the load on, you will take a chunk out of the bottom of the fuse.
 
  #22  
Old 12-26-10, 08:35 PM
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Originally Posted by Justin Smith View Post
If you leave the load on, you will take a chunk out of the bottom of the fuse.
Since when. I've changed 15 and 20 amp fuses all the time at the other house with the power on nothing unplugged. NOTHING EVER HAPPENED.
 
  #23  
Old 12-27-10, 07:54 AM
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I had fuses where there was a chunk taken out.
 
  #24  
Old 12-27-10, 05:07 PM
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Originally Posted by Justin Smith View Post
I had fuses where there was a chunk taken out.
A chunk of what is taken out, porcelain?
 
  #25  
Old 12-27-10, 05:17 PM
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I think Justin was speculating on a flash back as a heavy load is engaged when a new fuse is inserted boiling off metal on the bottom contacts. Not familiar enough with fuses to say if it ever happens but as earlier suggested turning off every thing on the circuit before installing a fuse is good practice.
 
  #26  
Old 12-27-10, 05:25 PM
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A chunk of brass at the bottom tip of the base was taken out. There were 2 window a/c units on that circut.
 
  #27  
Old 12-27-10, 05:36 PM
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Originally Posted by Justin Smith View Post
A chunk of brass at the bottom tip of the base was taken out. There were 2 window a/c units on that circut.
Shouldn't have been two ACs. The fuse may not have been fully seated which allowed arcing.
 
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