wrote in message
stuff snipped
Fuses fail from age/temp cycling. Since the lights SOMETIMES worked,
the fuse was not blown due to a short or overload - the fuse just
"failed"
I don't know how you can say that without examining the fuse close up.
Sounds like it may have crumbled from excessive heating from carrying too
much of a load. Only a hands-on inspection will determine that, and it
would probably mean cutting open the fuse to determine the failure mode.
Don't raise alarms where none are warranted.
I would say *exactly* the reverse is true when dealing a lethal
entity like 240VAC where a main fuse has failed and with so many other
unknowns. Not being concerned enough might lead to a similar set of
circumstances where a badly manufactured Chinese replacement fuse FAILS
to
blow and there's a meltdown as a result. A blown fuse is a warning that
something's wrong. Assuming it's just a failed fuse and moving on seems
to
be bordering on terribly careless. Each to his own, I guess.
FWIW, hearing about a fusebox in a home in this day and age raises an
alarm
in my head that there's a potential overload situation. While fuse
panels
of 200A certainly exist, every *residential* fuse panel I've ever seen in
the NE USA was a four banger with 15A screw-ins and a 60A total rating. I
realize that experience is terribly limited, but regardless, a blown main
fuse is not something to take lightly.
You need a picture of mine? 22 circuits, one of which is a 30 amp 220
pullout, and the other is a 50 amp 220 pullout.
Installed in 1978 when the house was built.
But bro, you're a *Canadian* (-: They've always done things a little
differently. I don't doubt you have a fuse panel, but that doesn't change
my experience, which is that fuse panels in the US are typically associated
with 60A service and most houses that I have seen that have changed hands
even once have had those panels upgraded to get approval for a loan or to be
considered insurable.
This site says:
http://www.faqs.org/faqs/electrical-wiring/part1/
Many jurisdictions, particularly in Canada, no longer permit
fuse panels in new installations. The NEC does permit new
fuse panels in some rare circumstances (requiring the special
inserts to "key" the fuseholder to specific size fuses)
So while you and others may have them, fuse panels are definitely on their
way OUT.
That site also goes on to say:
Fuses are prone to explode under extremely high overload. When
a fuse explodes, the metallic vapor cloud becomes a conducting
path. Result? From complete meltdown of the electrical panel,
melted service wiring, through fires in the electrical
distribution transformer and having your house burn down.
[This author has seen it happen.] Breakers won't do this.
Other than the garage circuits, which I have blown numerous times with
table saw, compressor, and various other "tools of high demand"I've
only replaced 2 fuses in 29 years. One of which was DEFINITELY a
simple fuse failure, and the second almost definitely (a lighting only
circuit with less than 800 watts maximum load on a 15 amp fuse - which
has not blown for the second time in more than 8 years.) It was
cracked in the "blow zone", the crack not visible to the naked eye
The first fuse, which was intermittent, had failed where the fuse
element contacts the threaded shell. The solder didn't fail, so it was
not a loose or oveheated fuse - the fuse element just cracked, right
next to the soldered joint. If the lights or TV were on for a while
they'd start to flicker a bit, then go out. Turn them off for an hour
and turn them back on, and they'de work. Being wired with aluminum
wire, I checked every connection on the circuit before thinking to
replace the fuse. All outlets are now CO-ALR devices. Maximum load at
any time during the problem time was less than 300 watts. Max circuit
load in previous 15 years or so? Who knows, but in the 8 years I'd
owned the house not likely more than 1500 watts or so - back before we
got the central vac it had likely run the vacuum a few times. That
(replacement) fuse has been there now something like 10 or 12 years.
Gack! You've got TWO items that are no longer considered codeworthy.
Aluminum wire and perhaps the last fuse panel installed in Canada. (-:
I don't know what the rules are up in the "Great White Way" or in other
parts of the US, but I assume one of the safety reasons for switching to
breakers is that they are much harder to override with pennies or
aluminum
foil. Not sure what the NEC has to say about installing new 200A service
with screw-in fuses in the USA and I certainly know that my limited
experience does not even speak for the USA NE - just the houses whose
panels
I have seen. All I know is when a fuse protecting an entire incoming
phase
fails, an investigation is warranted to determine the cause. Assuming
it's
simply a bad fuse is bad troubleshooting.
In this case, caution is especially called for because we just don't have
the information necessary from the OP to make a good call. We have no
information at all about the daily peak load he's putting on the panel,
either. We don't have a picture of the panel with the cover off, which
can
often tell you what kind of workmanship is involved or if the wiring is
shoddy or deteriorating.
I recall seeing one poster here show us a picture of his circuit box with
all of the single wires laid out as neatly as the strings of a harp! I
had
never seen and will probably never again see such incredibly precise
work -
I wish I could remember the dude's name - when you see workmanship like
that, you can usually discount poor wiring - but I digress.
My panel looks about the same, as did virtually every panel my
electrician father ever installed.
I don't doubt that, but most panels I've looked into don't.
With all the unknowns, it seems far more prudent to raise a caution flag
than to give him the green light and say "bad fuse, replace and
fuggedaboutit." The part of this that really gives me pause is that he
reported that it's an intermittent fault. Yes, fuses, light bulbs and
most
anything electrical can fail that way, but when a safety device fails,
it's
far more serious than a light bulb failure. When the fuse protecting an
entire leg fails, I consider that especially serious because it can
easily
indicate too much current is flowing through that leg, something that
individual circuit fuses will not catch.
It is just as irresponsible to scare the guy into spending big bux to
replace what may be a perfectly safe and serviceable fuse panel
No, I don't think so. If fuse panels were as safe and reliable as you've
been portraying them, then why aren't they allowed in new service? It's
because they have serious safety issues compared to breaker panels. "Safe
and serviceable" is hard to evaluate without seeing the box but we already
have good reason to believe there's something very wrong with it since a new
fuse didn't cure the flickering.
I also base my comments on the fact that I've never seen a screw in fuse
panel in all the new homes I've every looked at and I bought my first house
in 1984 and my parents bought several houses before that. The NEC decided
against fuses, and I'll bet those reasons are safety related. I assume the
primary reason is that fuses are too easy to bypass with higher-than-proper
rated fuses, pennies or foil. I assume a secondary reason is that when they
are unscrewed you can get shocked a lot more easily than when a breaker
trips. A tripped breaker has no potential exposure to electrical current.
More reasons? Fuses may not be screwed in completely and thus make
intermittent contact.
If the box and wiring are in reasonably good shape, and the load is
not over about 80% (70% is better) no problem.
We know none of those things. Another site says this about fuse panels and
why they've disappeared from new home wiring:
Old style distribution panels, those with screw-in fuses are generally
considered fire hazards. The contact between the base of the fuse and the
buss bar oxidizes or charcoals from poor contact. In order for the current
to continue to flow heat is generated. In many areas, insurance companies
will not renew homeowner insurance if the home is equipped with an
electrical distribution panel that has screw-in fuses. . . .Electrical
panels typically last 20-25 years. Sure signs of a failure in your
electrical panel are flickering lights and excess heat at the circuit
breakers.
Well, our OP certainly has experienced the flickering lights part.
Source:
http://www.allstarelectric.us/electr...lupgrades.html
The truth is that we don't know a whit about either of those big IFS in
this
case. We don't know how well the loads are balanced in the house - many
times one leg is bearing much more of the load than the other. That can
be
simply plugging in space heaters into the "wrong" outlets. In a house
with
a bigger circuit panel than the feeders dictate, that can happen easily.
I've seen more than one "heavy up" that didn't include an appropriate
upgrade from the feeder.
All we know here is that one leg of the incoming power lines had an
intermittent, not quite completely failed fuse. We know very little
else.
(Since writing this, the OP has added a post indicating that he's got
200A
circuit panel but we don't know if it's really 200A service or a 200A box
sitting on 60A feeder lines.) With no ability to go onsite, we've got a
barrel full of IFs that raise the caution flag.
Yes, I agree with you that fuses do fail from inherent vice but IMHO
*every*
fuse failure or circuit breaker pop warrants an investigation to find out
what popped it. In this case, I would be looking at the total KWh's used
monthly in relation to the size of the panel and also whether the panel
was
properly balanced with each leg carrying as close to half the load as
possible. I'd turn everything in the house on and get out my tong meter
to
see what branch circuits were carrying in terms of load. I'd visually
inspect the outside feeders to make sure they were sized for 200A and not
60
or 100.
IIRC, the panel should be sized so that even if every device in the
house is
running, the main fuse won't blow. I am not sure that's the case here.
We
also know fuses fail in multiple ways: in addition to failing
intermittently
or "popping" correctly in an overload, they can also fail to
blow and thus not protect the wiring. That's an extremely hazardous
situation.
Except in the case of cheap chinese automotive mini-fuses I've never
seen or had first-hand knowlege of a fuse failing to blow.
Well, explain why they're no longer going into new work if what those sites
are saying is true. The NEC wouldn't abandon a successful technology for
absolutely no reason, would they? (-:
As I am researching this, I keep seeing comments like this:
http://www.walleyecentral.com/forums.../t-152904.html
"I need to update the old screw-in fuse box on my cabin to modern breakers
per my insurance company. What should I expect to pay for a 100 amp service
upgrade? Wiring is modern 3-wire system, but for some reason, they never
upgraded the fuse box."
If the two fuses for each leg are of the same vintage, I would replace
both
of them if I wasn't going to heavy up the panel and the load appeared to
be
well-balanced. My best guess, from the limited facts we've been
presented,
is that the load is too great for the panel and that one leg was carrying
a
heavier share of the load than the other, causing the fuse on that leg to
deteriorate and partially fail.
Quite possible - even iff that leg was never over 50 or 60% capacity.
A good idea to check the load and load distribution? Most definitely.
But don't condemn the panel or the installation without checking it
first.
If the guy had flickering lights throughout the house, there's good evidence
the panel isn't working properly.
Not quite sure why the fuses with different sized cones, that did not
allow a heavier fuse to be installed than the socket was designed for,
never caught on. Likely because the American manufacturers took a
"not invented here" attitude. (I believe it was a Canadian inovation)
Those are Type S fuse receptacles that used different threads on each value
of fuse, making it impossible to substitute the wrong size. I had them in
this house when it had a 60A fuse panel. Different color fuses, too.
Since we're now six quotes in, we're just kicking the football around
now. It will be interesting to see what the final resolution of the problem
will be, but I am betting it's going to end in a panel upgrade.
http://www.city-data.com/forum/renti...use-boxes.html
says: "I've upgraded a number of panels from fuse to circuit breakers
because some Insurance Companies will no longer insure with fuses."
http://ezinearticles.com/?Upgrade-Yo...em!&id=2469061
"In California, if a home is equipped with an electrical distribution panel
that uses screw-in fuses, many insurance companies will not renew homeowner
insurance."
It really seems that I am not the only one who believes that fuse panels
should be replaced with breakers. Apparently the people that have to pay
out for electrical fires do, too.
--
Bobby G.