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Author Topic: 12VDC in-line fuse hot!  (Read 3907 times)

lucille

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12VDC in-line fuse hot!
« on: February 15, 2014, 08:23:41 PM »
The in line fuse holder for my 12VDC television in very hot to the touch. I have the correct fuse (8amp). I cleaned the contacts in the fuse holder and thought it cooled down a little. Today I check and it was hot again. Is this normal? I can't trace the wires behind the wall to check for problems there. The TV works and the fuse doesn't blow.

SeilerBird

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Re: 12VDC in-line fuse hot!
« Reply #1 on: February 15, 2014, 08:44:18 PM »
No the fuse should not be hot. Are you sure it is the right size fuse?
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lucille

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Re: 12VDC in-line fuse hot!
« Reply #2 on: February 15, 2014, 09:05:18 PM »
The holder says 8 amps. That's what it had. I put a 10 amp in today. I'll see how that works. I didn't know the large fuse could possibly run cooler. Is that an idea or do you know where it's made a difference? Thanks for your help.

denmarc

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Re: 12VDC in-line fuse hot!
« Reply #3 on: February 16, 2014, 04:37:51 AM »
Tom is correct.  Was the fuse holder added to the 12vdc cord or was it included with the TV when purchased?  Is the cord itself hot to the touch also?  How big of a TV are we talking?  It sounds like the TV is drawing power very close to the capacity of the 8 amp fuse.  To the point where the fuse is heating up but not quite to the point of melting it.  Putting in a 10 amp fuse may cool the fuse holder down, but you may be decreasing the protection the TV needs to prevent damage or fire by doing so.  Just because the fuse holder holder says 8 amp on it doesn't mean it's a 8 amp fuse inside.  I have seen many times cheap AGC (glass type) fuses with no markings on the metal ends so no way to be sure.  At the very least, I would try a true 8 amp fuse before replacing with a 10 amp.  Unless you know what your doing, never replace fuses with a higher amp fuse.  More info needed.
« Last Edit: February 16, 2014, 04:54:18 AM by denmarc »
Mark

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SeilerBird

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Re: 12VDC in-line fuse hot!
« Reply #4 on: February 16, 2014, 05:16:11 AM »
Is that an idea or do you know where it's made a difference?
It is simply the only thing I can come up with that would explain the problem.
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Ernie n Tara

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Re: 12VDC in-line fuse hot!
« Reply #5 on: February 16, 2014, 08:46:00 AM »
Usually, a heated fuse is due to a loose connection assuming the size is correct and the wire is good. Check across the fuseholder with a multimeter (may have to push the points of the probes through the wire insulation)  and you should get less than an Ohm. If not replace the fuseholder.

Ernie

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catblaster

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Re: 12VDC in-line fuse hot!
« Reply #6 on: February 16, 2014, 09:00:42 AM »
fuse holders like the one shown in the top picture (below) have a spring that maintains contact on the fuse, they will often get weak over time or heat and lose tension, if you have that type it is best to replace with one that looks like the second picture below. Check the back of your TV for the amp draw and get fuse slightly larger than that, someone here will know the correct amount to increase without sacrificing protection.
Will and Jane
95 Winnebago Luxor

tvman44

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Re: 12VDC in-line fuse hot!
« Reply #7 on: February 16, 2014, 09:43:30 AM »
Almost has to be a bad connection in the fuse holder.

John From Detroit

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Re: 12VDC in-line fuse hot!
« Reply #8 on: February 16, 2014, 03:56:48 PM »
8 or 10 amps too small a fuse will not cause it to get hot, Too small a fuse in fact will cause it to get very cool, since the fuse will blow and stop current from flowing.

The fuse holder may need replacement.  Dirty contacts WILL cause heat.
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carson

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Re: 12VDC in-line fuse hot!
« Reply #9 on: February 16, 2014, 04:10:45 PM »
John is quite right. A glass fuse is not a "heating element"...if if it gets too hot, it blows. That's what makes them blow. I'll go along with a defective fuse holder.

  If you put in a much larger fuse, something else will burn up. Probably the unit it is supposed to protect. That's my logic as well.
Carson, 
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lucille

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Re: 12VDC in-line fuse hot!
« Reply #10 on: February 16, 2014, 05:23:03 PM »
I really appreciate all the good advice from my fellow forum members. The fuse holder came with my RV brand new. The fuse is in fact 8AMP.  The wiring does not get hot at all. Yes the plastic holder is what gets hot. I cleaned the holder contacts really good. I like the spring tension comment. I'll change the fuse holder for sure and post what results I get. Again, I am a big fan of this forum because of helpful people like you. By the way, I call my Harley by the name of Lucille; that's why I use that as my forum name. :)

SeilerBird

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Re: 12VDC in-line fuse hot!
« Reply #11 on: February 16, 2014, 06:00:22 PM »
By the way, I call my Harley by the name of Lucille; that's why I use that as my forum name. :)
And here I thought you were BB Kings guitar :o
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denmarc

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Re: 12VDC in-line fuse hot!
« Reply #12 on: February 17, 2014, 06:33:02 AM »
John is quite right. A glass fuse is not a "heating element"...if if it gets too hot, it blows. That's what makes them blow. I'll go along with a defective fuse holder.

  If you put in a much larger fuse, something else will burn up. Probably the unit it is supposed to protect. That's my logic as well.

I never meant to imply that the fuse was a "heating element".  However, I have seen inline fuse holders get hot enough to turn color and show minor melting due to heat build up with the proper fuse installed.  All points of contact were clean and tight. The amperage draw has high enough to warm things up, just wasn't at the point of "blowing" the fuse.  Reading the OP's post literally, I assumed good electrical contact in the fuse holder in question.  Maybe my bad.  If not the case, I agree with others pointing to high resistance (bad connection) in the fuse holder due to the fact the wire on either end of the holder are not warm to the touch.   
Mark

1994 Jayco Eagle 370FB on 24 acres of paid off paradise in Michigan.

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Coach_Frank

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Re: 12VDC in-line fuse hot!
« Reply #13 on: February 17, 2014, 08:17:13 AM »
By the way, I call my Harley by the name of Lucille; that's why I use that as my forum name. :)

So is Lucille the name you want to be called? Or do you prefer something else?
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lucille

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Re: 12VDC in-line fuse hot!
« Reply #14 on: February 17, 2014, 05:53:20 PM »
For those who helped me with the hot fuse holder, I changed to a blade type fuse holder. No more weak spring to worry about. Tomorrow I'll should have enough time to give it a good test. I'll post how it works.

 

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