Call me a "luddite" but I'll trust a fuse over a breaker for
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
Breakers are more convenient - but not necessarily better (unless you
have Mag-trip breakers, which are MUCH more accurate than fuses.
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.
This is probably old news around here, but I though it's related to this
134 Field reports of Federal Pacific Electric FPE Stab-lok electrical
equipment failures, 2003-2005
Here is a few no-trips with photos http://www.inspect-ny.com/fpe/fpefire.htm
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
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.
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. :-)
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
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
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
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.
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,
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.
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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