Fuses in box get hot when using Kenmore Electric Dryer (only on heat cycle)

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wrote:

Call me a "luddite" but I'll trust a fuse over a breaker for "durability" A fuse has NO moving parts - no pressure contacts or wiping contacts. Every time a fuse blows it is replaced with a new one. Every time a breaker is tripped under load, whether intentionally or due to a fault (overload or short) the breaker deteriorates. Just be sure a fuse is always properly installed, and a bit of dialectric compound on the threads and tip never hurts - prevents corrosion. Breakers are more convenient - but not necessarily better (unless you have Mag-trip breakers, which are MUCH more accurate than fuses.
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snipped-for-privacy@snyder.on.ca wrote:

Luddite.
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snipped-for-privacy@snyder.on.ca wrote:

I agree. A 20A fuse after 20 years should have the same characteristics as when new. A 20A breaker could freeze mechanically. Would be interesting to look at the trip points of old breakers. I think someone was going to run tests on old houses.
In applications with high available fault currents, fuses with high fault current ratings are readily and cheaply available.

Hard to argue with the convenience.
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wrote:

Mechanical freezing is extremely rare, while false tripping due to resistance heating of the contacts is quite common - more common on some makes than others.

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wrote:

This is probably old news around here, but I though it's related to this post.
134 Field reports of Federal Pacific Electric FPE Stab-lok electrical equipment failures, 2003-2005 at http://www.inspect-ny.com/fpe/fpefield.htm
Here is a few no-trips with photos http://www.inspect-ny.com/fpe/fpefire.htm
Cheers, Jim
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wrote:

OK, name plate reads "Motor 4 Amps - Heater and Accessories 23 Amps".
Thanks, Jim
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Since the 30A fuses are *not* blowing, I suspect that the heat is a problem within the fuse panel itself (high resistance connection) checking the current draw of the dryer should confirm this.
nate
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snipped-for-privacy@optonline.net wrote:

I agree with that, I've never seen a normal sized electric dryer here in the US of A which didn't have the heaters powered with 240 volts using both legs of the feed circuit.
That said, I'm a little suprised that the 15 amp fuse the OP said he put in "the motor side" didn't blow.
At this point I'll allign with the folks who have told you to junk that Dryer Fuse Box and install a breaker box.
For several years I had ongoing problems with a fused disconnect switch supplying 240 volts to the supplementary resistance heaters in one of our home's heat pump air handlers. The switch contacts would oxidize, start heating up and raise the temperature of the end cap of its adjacent cartridge fuse to the point where the fuse link would melt or sometimes the solder jointing the fuse link to the end cap melted and disconnected it.
That fused disconnect and air handler are in our attic, which is definitely not a "moisture laden" area.
Cleaning and "tightening" the switch contacts would only solve the problem for a few winter months before it recurred.
I gave up and replaced the entire fused disconnect with an identical one and a couple of years later the same damn thing started happpening.
I (think) I finally put the problem to bed by replacing that fused disconnect with an unfused "pull out" disconnect about 5 years ago. There was no need for fuses there anyway, because the line feeding that disconnect is protected by breakers at its feed end, the disconnect is just a code required safety feature to protect service techs.
Jeff
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wrote:

Yeah I was expecting the 15 to blow too, I ran the unit for about 10 mins. I got a tester today and that line tests around 21 amps. It was a TimeDelay fuse, but I don't think it should delay that long. :-)
Cheers, Jim
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wrote:

Yeah, it's was a 15 AMP Time Delay fuse and I ran the unit for maybe 10 mins. I bought a Clamp On Amp tester today and that line tests just about 21 amps.
Cheers, Jim
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wrote:

Well, I got a new Clamp Amp Meter, at Home Depot $50. Harbor Freight was out of the cheap ones even after I called to confirm their stock.
I tightened the screws (the screw under the head of each fuse) in the fuse holders and installed two new 30A fuses. I believe these screws came loose from the hot and cold cycles. It's a ground level room that's not heated. I did two loads tonight and they never got hot, just a very slight temp increase.
The name plate reads "Motor 4 Amps - Heater and Accessories 23 Amps".
I tested both lines, before and after the fuse, and at the dryer outlet and found no difference per side.
-Cold start Dryer running on AIR cycle, the Motor side tested at = 21.73A, the Other side (I call it the heater side) tested at = 3.71A.
-Dryer warm running on low/med/or high heat. Motor side = 21.5 +-.3, the Other side was slightly higher = 23.6 +-.3. I took several readings over a 40-50 min period, all about the same per side.
So I think the Dryer is safe.. Right? But I still wonder why one prong in the outlet was fried. Maybe the wire was loose? I didn't pay attention when I replaced the outlet. Maybe I damaged it when cleaning the exhaust vent (about twice a year), I have to unplug the dryer to move it.
I will pickup a breaker box and replace the fuse box. I had two in my hand today at HD, it holds just two breakers, just what I need. They only had two of these in stock and after opening both boxes they both had parts missing. I could have completed one box by using parts from the other, but instead I took them both up to CS. I'm only about 15 mins from another HD.
Thanks to everyone that contributed to this post, I appreciate it
Cheers, Jim
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Jim2009 wrote:

I'd expect that rather than using two breakers it'd be safer to use a "double pole" 30 amp breaker, like this one:
http://tinyurl.com/axxud3
Somebody please correct me if I'm wrong.
Jeff
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Jeff Wisnia wrote:

No, you're correct. Either the breaker shown or a pair of "ganged" breakers.
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Good point...... I seen those, but I was leaning towards buying two singles since it was a few bucks cheaper. I didn't think about the benefits of the common trip. Doh!
Thanks, Jim
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On Wed, 21 Jan 2009 10:46:14 -0500, Jeff Wisnia

BY LAW that is the only kind of breaker he can use - it must be impossible to shut down or trip one side without shutting down or tripping the other side. (so either DP breaker, or mechanically tied trip levers)
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Jim2009 wrote:

If the load on the 15A fuse was 21A (from measurements below) the fuse should blow. Time depends on type of fuse. For a 15A SquareD breaker the trip time would be 25-125 seconds. If you actually had 21A through a 15A fuse the holder could be shorted from the center contact to the screw shell. Unscrewing the fuse should kill the heat or the whole dryer (depending on which).

If they stay cool you might have fixed it (or as noted above).

Don't know as how those make sense. If the heater ran on 120V it would draw a lot less than 21A. Presumably the heater is not running on "air cycle". If the meter sets the range automatically you may be reading the decimal point wrong, like 21 mA. 3.71A is reasonable for the motor.

Heater appears on both fuses and is 21.5A approx. compared to the nameplate of 23A
Motor appears on only one wire (should be "other side")and is 23.6 - 21.5 = 2.1A approx. compared to the nameplate of 4A. Should increase with more load in the dryer, or wet load.

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wrote:

I justed pulled the fuse and checked the socket with an ohms meter, no short. I did another AIR cycle test and discovered I been telling you wrong I got my wires (sides) switched! Doh..Doh..!#%#!#$#@ So when I put the 15A fuse in ...in was in the heater only side and not the motor/heater side. I know I ran it on the heat cycle, but I must have ran it at the end of the cycle, cool-down portion so little or no heat.

Yeah the above statement does not make sense, will retest it. I had it running on a Heat Cycle for about 20 seconds then I flipped it to the Air only cycle and took readings, maybe the heat stayed on for a few seconds or more likely I read my notes wrong?

Yeah, the heater uses both sides. Plus, I had my sides switched in my notes, so on the Air cycle the motor side = 3.71A, the heater only side is 0, (I just re-tested it). When I run a Heat Cycle the motor/heater side increases from 3.71 to 23.6 +-.3, and the other heater only side increases from 0 to 21.5 +-.3.

Umm, I gave you bad info, so that's not true. The motor is 3.71A, the heater on the motor side is approx 20A (23.6 - 3.71 = 19.89), and the other side (heater only side) is approx 21.5A.
Thank you for your time, Jim
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wrote:

You don't understand how that thing is wired. You have 3 wires. The heater connects from the red to the black. That is from fuse 1 to fuse 2. and is nominaly 240 volt. The heater does not know the white wire even exists - so whatever the heater draws on the one fuse, it draws EXACTLY the same on the other fuse. The motor and the timer motor run on nominally 120 volts , which is from one fuse to the neutral.
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wrote:

I'm just saying what the meter reads, no heat 3.71A on one leg, with heat the same leg increases about 20A, and the other from 0 to about 21.5A. I don't know why they are different but it's plain to see that there are.
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wrote:

I think you still have a connection problem somewhere and you are still making heat somewhere other than at the element.
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