A simple question about an old fuse box and fuse capacity

Discussion in 'Electrical and Wiring' started by adifrank, Jul 13, 2019.

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  1. Jul 13, 2019 #1

    adifrank

    adifrank

    adifrank

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    Hi : )
    I have what probably is a very simple question and thought this forum would surely be a good place to ask it.
    In the apartment I'm renting in the Los Angeles area I have an old looking fuse box that looks like this:
    IMG_20190713_100652069.jpg
    The cover to the box has the following info:
    IMG_20190713_100645733.jpg
    Currently when connecting a toaster oven (1500W) while the standard stove/oven is on (1500W) the fuse goes out and I need to replace it.
    From what I understand from researching the web, to use both ovens totaling 3000W, I would need a fuse with 25 Amps capacity
    3000W/120V = 25 Amps
    However, I'm not sure I can use a 25 Amp fuse instead of the 15 Amp fuse currently in the box.
    Is a 15 Amp fuse the max I can use with this box?
    And if so, how come there's a 20 Amp fuse in there?
    I would ask my landlord, but I feel that I've bothered him with too many questions about the apartment and I'd rather figure things out myself to avoid being too much of a pain, if I can.

    If someone can help me figure this out, that would be great.
    By the way, if I use the toaster oven on a different outlet, then it works fine with the standard stove/oven, but the location is much less convenient and not practical.

    Looking forward to explanation and recommendations on how to remedy this.

    Thanks!
     
  2. Jul 13, 2019 #2

    drumz

    drumz

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    15 amp is what it is designed for and anything over that heats the wires which can cause a fire. There are breaker fuses now that have a little button in the middle that pops when the circuit gets too hot instead of breaking and having to replace the fuse. And unfortunately it is a location issue since it appears that your oven and toaster oven are on the same circuit. Nowadays the oven has a dedicated circuit. Maybe a good extension cord would help.
     
  3. Jul 13, 2019 #3

    adifrank

    adifrank

    adifrank

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    Thanks drumz!
    Okay, I just want to fully understand a couple of things:
    1. I'm not able to figure out why the breaker box label on the cover says 30 Amps if 15 Amp is the max capacity. Do you mind helping me understand this? (see image in original post)
    2. Currently there are 2 fuses that say 15 Amp and one that says 20 Amp (see image). That's how it was when I entered the apartment. Am I correct in understanding that the fuse saying 20 Amp could be a hazard? Should I replace it with a 15 Amp fuse?

    Thanks!
     
  4. Jul 13, 2019 #4

    drumz

    drumz

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    An electrician can answer about those old boxes, I don't want to say something inaccurate. Another forum I go to that has an electrician corner https://www.doityourself.com/ is worth a try.
    With your box, someone probably put a 20 amp fuse in there because it kept breaking/ getting overloaded so yes, it is potentially dangerous.
     
  5. Jul 14, 2019 at 1:03 AM #5

    hornetd

    hornetd

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    The number on the panel label is how many amperes the box is laboratory listed to carry in total. Because it always gets asked that number does not mean that the total of all the installed fuses must be smaller than 30 amperes. So the number on the panel cover is of no use to you. Fuses are, OR SHOULD BE, selected for the size of the wire that they protect. An American Wire Gauge size 14 (14AWG) size wire must be protected by a 15 ampere or lesser rated fuse. A 12AWG wire is limited to a 20 Ampere fuse. [Because the people who devised the American Wire Gauge thought that Size 1 was the largest wire that would ever be made and they didn't know what the smallest wire that might be possible was, the AWG number goes up with each reduction in the wire size. When the size of wires began to get larger sizes Ø, ØØ, ØØØ, and ØØØØ; or 1Ø, 2Ø, 3Ø, and finally 4Ø; were added to the AWG gauge before they finally gave up and began expressing the larger sizes in Million Circular Mills or MCM.] In this use the Ø is said "aught."

    Why your landlord has not had those fuse holders fitted with type S adapters to prevent over fusing I will not even try to guess. So if you change the fuse on a 12 AWG wire to 25 you are guaranteeing an electrical failure on that circuit! The unknowns are how soon the failure will occur and will it result in a sufficiently prolonged arc to kindle a fire.

    The real answer is that you need to leave the fuses sized as they are since you have already shown that you do not know enough about the basics of electrical wiring to even consider doing any electrical work. I am retired out of 45 years of active fire and rescue service as a volunteer and 55 years in the electrical craft. I do know whereof I speak! Consider carefully what kind of clothing you would like to have the worker coming to your building to be wearing. In your case the choices may be the ordinary looking non flammable clothing worn by electricians or the complete protective ensemble worn by Firefighters.

    Given that you are in Los Angeles County there is a chance that the wiring was done with rigid metal conduit. If that is true then the cost of rewiring one of your circuits need not be terribly high.

    Quality can be illustrated in the purchase of oats. If you want nice clean fresh oats you must pay a fair price. If you will be content with oats that have already been through the horse you can pay slightly less!

    --
    Tom Horne

    Well we aren't no thin blue heroes. Yet we aren't no blackguards to. We're just working men and woman most remarkable like you.
     
    billshack likes this.
  6. Jul 14, 2019 at 1:26 AM #6

    adifrank

    adifrank

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    @drumz, thanks for the help and the link!
    @T. Horne, thanks for the explanation, and thanks for your service!

    Seems clear now. I'll just keep the fuses as they are : )
     
  7. Jul 15, 2019 at 3:06 PM #7

    Diehard

    Diehard

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    A 30 amp service is considered inadequate for modern living.

    As mentioned above, at a minimum, the fuse types should have been switched to type S, which prevent putting in the incorrect fuse size. However, when they are put in, they must be selected based on the wire size of the circuit they are protecting.

    The National Electrical Code (NEC) does not allow the old type fuses but do allow the Type S types.

    Get after the owner of your apartment to update your archaic electrical service.
    I'll bet that most insurance companies would not insure a house with a 30 amp fuse service.
     
  8. Jul 16, 2019 at 12:20 PM #8

    afjes_2016

    afjes_2016

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    And please do not use an extension cord for things like a toaster oven. If anything unplug it and move it to another location and plug it in directly in the receptacle.
     

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