Wierd Fuse

I'm stumped. The wife says last night at bed time, "The dryer's not working. I have to put a load through 3 times for it to get dry." Now that makes for a restful night's sleep, hunh!
I checked the dryer with a load running. First time it felt warm, but not really hot. 10 minutes later it felt really hot, then after another 10 minutes it felt lukewarm again.
I have an older home with a fuse panel. I pulled out the fuse block with 2 x 30A fuses, and checked them with my meter. The one fuse initially showed 15 ohms resistance, then settled within 10 seconds to 0.2 ohms. The other fuse was a different story—the meter reading continued to fluctuate widely from 1 ohmn to infinity for as long as I watched it. It would seem to read between 0.2 and 30 ohms for awhile, then between 80 and infinity for awhile, then back to 0.2 – 30. Weird.
I put in a new fuse, and it seems to be heating up better.
I'm assuming the fuse failed, but I would have expected to see no continuity. Why would I be seeing fluctuating resistance readings?
PS. My meter is a Sperry DSA-700 Digisnap.
Mr Fixit eh!
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Steve,
I'm don't believe that you've fixed your problem. Your dryer spins and heats. Therefore I see no reason to check the fuses. The readings you made might indicate a poor connection between the meter and the fuse. Let's give some thought to the symptoms. Your dryer does dry but takes a long time. I'd check for build up of lint in the outlet or the filter.
Dave M.
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David Martel wrote:

Well, consider this....
The dryer motor may be running off 120 volts, from one side of the 240 to neutral. That side may have a "good" fuse in it, and the other fuse is flakey, resulting in intermittant heating of the dryer element.
It may not be the fuses themselves. It's more likely to be the contact between the fuse clips and the fuse's end caps, or even between the fuse block's blades and the recepticles they plug into in the panel.
The OP didn't say where he touched his meter probes to the "fuses", but it might not have been directly onto their end caps, in which case poor contact between the fuse clips and the fuse end caps could account for the readings he saw.
He might try cleaning up the fuses and clips with some fine sandpaper, and maybe springing the clips closed a bit if they seem loose.
I've been snookered by bad contacts between cartridege fuses and their contact clips more than once in my life, though usually the current flow through an imperfect contact heats the fuse end cap enough to melt the fuse's link, resulting in a "blown fuse" with no apparent source of overload.
There's a clear liquid called "Stabilant" which is an almost magical conductivity enhancing material. It's excellent for keeping those kind of poor contact situations from developing. I've found it particularly useful on the contact blades of fused disconnect switches, which can display a proclivity for developing poor contact with resulting heating after a few years, especially if they haven't been operated during that time. That heat can flow from the stationary switch contact to an adjacent fuse clip, "blowing" the fuse with heat.
http://www.stabilant.com /
All that said, I believe in Ocam's razor, and the problem is quite likely to be what you stated, a clogged filter or dryer exhaust system, and the dryer element is cycling off and on via its overtemperature thermostat.
HTH,
Jeff
--
My name is Jeff Wisnia and I approved this message....

(W1BSV + Brass Rat '57 EE)
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On 15 Sep 2004 06:26:22 -0700, snipped-for-privacy@hotmail.com (Steve Nekias) wrote:

A common cause for this is the vent getting plugged up with lint. You might want to clean the whole thing out. I wouldn't expect a fuse to fail in the way you describe.
Steve B.
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Thanks for your help guys...the wife is happy now. There was indeed a large build-up of lint in the blower motor/filter/ductwork--about 4 cups full!!! I bought the dryer about 4 years ago and I've been procrastinating on cleaning out the lint for a couple of years now.
The wierd fuse was just I was not making firm enough contact with the fuse. The fuses are not cartridge type, but 2 standard 30A fuses that screw into one fuse block that clips into the panel. You have to remove the fuseblock before you can remove either of the fuses.
I tested the continuity of the heater element at 10 ohms and there is no continuity to the chassis. There is 240volts between the heater element leads with the dryer turned on.
She's hot now (the dryer)!
Mr Fixit eh!
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On 15 Sep 2004 18:44:19 -0700, snipped-for-privacy@hotmail.com (Steve Nekias) wrote:

Good job Mr. Fixit. Thanx for letting us know the outcome.
Steve B.
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Is the dryer gas or electric? If it's a gas dryer, I'd look somewhere other than the fuses.
;-)

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