Good question. The 1500 to 2000 dollars suggested would buy a heck of
a lot of fuses. I think I've tripped my circuit breakers less than
40 times in 20 years, maybe less than 20. And if I were more careful,
it would be less than 10. What do fuses cost, a dollar a piece? 40
dollars versus 1500?
The benefits of a ground fault circuit breaker can be achieved by
putting a ground fault receptacle in place of the receptacle closest
to the fuse box.
If a particular circuit is blowing often, they make or used to make
resettable circult breakers that screw into a fuse socket. AFAIK,
they work fine..
I once bought a house that had a 60A fuse box. The sellers insurance co
insisted that the servive be upgraded to 100A breakers before we bought it.
It may be that the 60A was more of the reason than the fuses though.
It did happen. There were only 4 circuits in the entire house, plus an
Edison circuit for the dishwasher / disposal that someone added in a small
subpanel. The entire rest of the kitchen, garage (including laundry) were
on one 20A circuit. (That fuse was blown when I first looked at the house).
After I moved in, and after the fuse box was replaced, the wires on that
kitchen circuit would be warm to the touch. I rewired much of the house
adding about 8 new circuits and split up several circuits. This is all work
I expected to do after taking one look at the fuse box. In my case I was
lucky because the seller paid for the service upgrade and breaker box.
~$1800 for a new breaker box, meter base and head, ground rod, etc. This was
6 or 7 years ago in Bay Area CA.
That can involve a "major" service upgrade and,
increasingly, inspectors are requiring that other
parts of the wiring system be brought to present
Call the Building Dept in the locale you're looking
at and ask what requirements they have in such situations.
Also, talk to the insurance agent who covers your home
(or will be) and ask what requirements *they* have for
policyholders regarding outdated elctrical systems.
Might be surprises lurking there too...
you'll be upgrading that single home 110v fuses 60 amp service to
include power for air conditioning and replacing the line from the pole
with a nice 200 amp or more 220v service? any aluminum wiring problems?
any knob and tube wiring problems?
read about "I'm buying a house! What should I do? What is this weird
stuff? Old style wiring" and more at:
This is something that you should try to get the seller to do as a
condition of purchase. Chances are pretty good that if they have the
old 60 Amp "Main, Range and Four" fuse panel that the entire house
probably needs rewired. Usually in houses like that 2 circuits pretty
much run most of the outlets and lights.
All good advice. I'm very literal, and when I suggested not upgrading,
I was assuming that fuses were the only "problem", since that is all t
hat he asked about. It's good to go beyond what an OP asks.
It would be interesting where the stats came from. I have probably seen
more arcs develop from a plug-in breaker to the bus bar. If using
Fusestats, which are readily available non-interchangable plug fuses,
the wrong size fuse can't be used, nor can the fuse be bypassed with a
Fusestats have an interrupt rating of 10,000 Amps, same as residental
CBs (recently some are higher). Cartridge fuses that should be used have
an interrupt rating 100,00A or higher. Breakers won't explode on short
circuits (not a high overload)? How about if it is mechanically slow or
frozen? Anyone still make crappy CBs (ala FPE or Zinsco)?
The "special" inserts to convert to Fusestats aren't particularly
special and often have been installed in old panels.
The fuse is not there primarily to protect the motor from overload. It
protects the supply wiring from short circuits but gives some protection
to the motor and other equipment in unusual circumstances. That is the
same function the CB provides. I presume the manufacturer likes the
operating characteristic of the fuse better.
CBs are a lot more convenient than fuses. However I wonder about 10 year
old panels. It would seem like a breaker could mechanically deteriorate
and freeze or have its operating characteristic change. If a fuse
element deteriorated it should open early. Anyone seen long term
reliability information? Would seem like someone would have run tests.
Like mm, I don't think I would change out a fuse panel if my house had
one, if it was large enough. But I wouldn't install one either. I think
the advantage of CBs, other than convenience, is overstated.
Fused service panels do come in ratings larger than 60A. When I was a
kid the service in my home was replaced with a 100A all fuse service
panel. It was 'main and range' style similar to volts500's description.
A 60A pullout fed 8 branch circuits. There was a 60A pullout for
possible range and I think 1 or 2 30A pullouts. The pullouts were all
service disconnects. (I don't think 'main and range' is allowed for new
Well you cant get arc fault detecting fuses, so eventually everyone
will be required to upgrade.
I would get some quotes for a new service, 100 and 200 amp and have the
seller discount the house that cost of at least the 100 amp upgrade.
it saves you bucks, and doesnt make him spend $ he might not have right
since the service isnt really unsafe you can do the upgrade when you
IF YOU HAVE THE SELLER DO THE UPGRADE IT WILL BE THE CHEAPEST JOB
I cowrote the FAQ, and authored that section. So, I think I can justify
That rationale has been explicitly stated (without giving specific numbers)
in many trade and media articles, pamphlets from the Canadian government and
in various guides (eg: Knight) for at least 20 years. Including the code
sections of course.
Let me tell you a little story:
In 1974, as a 19yo, I wired my grandfather's cottage, with my grandfather
and father as "laborers". Winterized, electric heat, 200A fuse panel,
fully inspected ("one of the best jobs I've seen!"), additionally with
my father, who's both DIY-minded and an engineer watching me _very_
I've spent _very_ little time (no overnighters) in the cottage since
the mid 80's. My parents, my brother's family and an intermittent
stream of their friends renting it by-the-week used it since then.
About 3 years ago, my dad started complaining that the cottage seemed
to be consuming a lot of electricity, without anyone being there - the
only electrical consumption was one small fan heater with a special
thermostat to keep the pipes warm in a small insulated space.
He also mentioned that one of the wallmount electric fan heaters seemed
to be defective.
About 18 months ago, my dad started making noises about selling it - since
the GPs and my mother had died, my father was making very little use of it,
and even with the sporadic rentals bringing in enough to maintain it,
it wasn't justified to keep it any longer.
Being the dutiful son, my wife and I volunteered to help tune up the
cottage for sale. During one visit I made a minor tweak to an electrical
circuit. My grandfather had installed a ceiling fan by mid-air splicing some
zip cord (!!!!!). So I installed a proper outlet and fan-control switch.
Then realized that some of the fuses in the panel were the wrong value -
a 30A on a 15A circuit.
Obviously my brother, who is the exact opposite of DIY-minded would replace
a blown fuse with anything handy without even looking at the fuse value.
Still little idea of what the excessive consumption was caused by.
Next time we went to the cottage, I brought two boxes of 15A fuses,
and spent the afternoon "auditing" the panel and making sure each
fuse was right for the wiring. I had to buy a third box of 15A fuses
and a couple of 20s...
While making sure that each fuse was solid, I burned my fingers on
one of the 240V fuse-pair blocks.
What the hell?
Turns out that the fuse contacts to the supposedly burned out heater had
sufficiently corroded/burnt, that it was providing a couple amp
flow to the heater which had been switched on for a very long time.
Not enough to make the heater noticably warm or the fan operate, but
enough to pull significant amounts of electricity and not _quite_
flame out the fuse block.
[I replace the fuses _and_ fuse block to be certain of the repair.]
That was one bullet we dodged.
[The other was, when asked by the electrical supplier "do you want to
use aluminum or copper"? "What's the difference?" "Copper is mechanically
easier, aluminum is cheaper". "Please grandpa, can we do the easier
one?". He went for "easy". Thank heavens for that!]
That's how just _one_ fuse panel "evolved" over 30 years - wrong fuses,
overheating connections. That's _why_ CBs are required these days.
[The cottage got sold, complete with a several hours worth of "owner's lecture"
by us ;-)]
The one other major catastrophe I've personally seen involved
a 60A fuse exploding in a commercial building. The resulting plasma
arc-over slagged two floor-to-ceiling panel sections, blew 2 of 3
2000A fuses (600V 3 phase service), and started a fire on the utility
pole. Not to mention vaporizing the electrician's coffee cup.
I've encountered a number of broken CBs in my day (including
3 of 4 Square D (I assume "Homeline") breakers in my damn cooktop!),
and not _one_ of them failed "badly". They simply tripped and wouldn't
I've _never_ heard of a CB "exploding". Failing to trip, failing to
reset, yes. Never exploding.
They're relatively special here, because hardly anyone uses them.
Read your code book and the equipment instructions.
Large motors (eg: in ton-rated builtin A/Cs) that don't have integral thermal
protection _often_ require a "nearby" fuse block sized _exactly_ according
to the plate/installation instructions, in addition to the normal branch
circuit breaker (which may be rated somewhat higher, and in some cases
The reason for this is that properly sized "regular" fuse response
closely mimics the current overload/thermal failure path of these motors.
As such, these fuses are primarily to protect the motor - since they're
local to the motor, they will _not_ protect against upstream circuit faults.
It's the job of the circuit breaker (or fuse) to protect the circuit.
Circuit breaker overload response is very similar to fusetron ("time delay
fuse") response. Fusetrons are what are usually specified for motor circuits
that don't need the local fuse block. Eg: furnace blower & water pump circuits
(these motors have builtin thermal protection, and hence don't need the fuse
trick). This is why you don't have to worry about "time delay" versus "regular"
with CBs, but you do with fuses.
I haven't seen formal reliability info, but according to my personal
experience, and what is evident in the electrical code evolution,
this isn't nearly the issue of fuse panels allowed to deteriorate.
Like I said. We had a 200A one.
I'm not familiar with "main and range" panels. Bigger fuse panels
tend to have 2 (or sometimes 3) pullouts for cartridge fuses, plus
pairs of screwin fuse sockets. In the cottage panel, it had 2
pullout blocks (stove and dryer), plus each pair of fuses were installed
in a "carrier" block which in turn plugged into the panel.
The "carrier" is either an "open style" (open access to two fuse
sockets) or a closed style (two hinging doors that cover the fuses -
you have to pull the carrier out to change the fuses - required for
240V circuits to ensure that both fuses were out when working on the
A good unit. But not one I'm comfortable with my brother maintaining .... :-(
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
I would actually be interested in event based stats. I don't remember
reading articles in the US (but could have missed them). Older fuse
panels may not be made as well and be less reliable (but I havn't seen
information suggesting this).
Fuses are readily available at low cost (such as Buss FRN) that are
"current limiting", meaning they open a circuit in less than 1/4 cycle -
significantly before the fault current sine wave reaches its first peak.
This is a major feature since magnetic effects than can tear loose bus
bars are proportional to current squared. It also greatly reduces
heating effects that, for a short, are proportional to current squared
times time. These fuses also limit the available fault current
downstream, which non-"current limiting" devices can't do. This is a
major advantage for not only equipment but safety of electricians. It is
a lot harder (and a lot more expensive) to get a CB to operate fast
enough to be "current limiting".
Fuses are also readily available at low cost with interrupt ratings up
to 200,000 amps. (On reason is they are "current limiting", as above,
and interrut the fault long before it reaches 200,000 amps.) It is a lot
more expensive to get CBs with that high a rating. In fact series
combinations of fuses and CBs are sometimes used, and old CBs can be
protected for a higher available fault current than they were rated for
with an engineered retrofit series combinations.
It is reasonable to assume your 60A fuse was not rated for the available
fault current. In the US its use is a code violation (as would be a CB
not rated for the available fault current). I would also wonder about
the service fuses if there was a fire on the utility pole. This
certainly does not reflect on fuses.
In high available fault current applications I would be especially
concerned by the long term reliabiliy of CBs since even a mechanically
produced slow trip on large fault can have dire consequences. Scheduled
testing of such CBs is sometimes done.
Suffice it to say CBs do explode. If they trip slow (or not at all) on a
high current fault magnetic and thermal effects can do awesome things.
Actually I have read my code book. The NEC divides protection into
"short circuit" protection for the conductors (and to a limited degree
for the equipment) and "overload" protection, which protects both the
motor and the conductors. In general "overload" protection is provided
by internal thermal protectors or sensors or by overload units in a
motor starter. The overload units can be 115% max of the motor run amps.
Fuses are not made in enough sizes to provide this protection. (Note
that the supply wires are protected from overloads at the load end.)
Fuses and circuit breakers provide "short circuit" protection. Hermetic
air conditioner compressor motors may be more complicated since they are
subject to heating from the compression and also have heat removed with
the exiting refrigerant. I presume integral thermal protection or
sensing is more effective.
I do not know what a "regular" fuse is. We have time delay (with several
delay curves) and non time delay. Non time delay would have to be sized
much higher than the run amps to avoid blowing on motor start - 300%
max. Time delay fuses can be sized up to 175% of run amps, again to
avoid blowing on motor start.
I've _never_ heard of a CB "exploding". Failing to trip, failing to
reset, yes. Never exploding
I used to repair machines at a westinghouse power systems plant. they
built breakers and panels. they had troubles with a foreign company
building knocks offs. from the outside they looked genuine. Inside they
I found out about this one day when walking thru the plant I heard a
explosion. Wierd the workers went on as nothing happened, I was ready
to run for my life.
just another test of a knockoff:(
properly built breakers shouldnt explode
lol the ultimate keeping up with the Jones's- now how good your switchboard
you may be able to get CB's to fit in the fuse holder in your area, making
it a possible DIY project.
it is true that fuses are more dangerous but only because the wiring in the
house is old and failing and lack of maintenance with appliances etc. CB's
wont fix and old house so if there are problems they will need to be
addressed before the house burns down..
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