Bought a new air conditioner this weekend. Thought the higher BTU unit
might put too much of a strain on the circuit and cause it to blow a fuse.
Turns out to be on a separate circuit from the air conditioner upstairs and
didn't have any problem. Still, it got me thinking about this old fuse box
down cellar. It's at least 30 years old or more and this may be the time to
think about updating to a circuit breaker and rewiring some of the house.
Checking the box tonight I noticed there were a couple 30 amp fuses and the
rest were 20 amp fuses. I don't know much about electricity, but I have a
feeling 30 amps is on the high side. Not only that, the outlets throughout
the house are of the two prong variety. Whenever we plug in a 3 prong
object, we need to use an adapter. Nothing is properly grounded. The
television and computers are my biggest concern. Then again, I simply turn
off the computer during any electrical storms.
Here's my dilemma. I am not really having any problems with the electricity
in our house. Thus, the old adage. 'If it ain't broke, don't fix. I
figure it will be close to $2000 to update.
My worry is that the 30 amp fuses are probably carrying too much of a load
and could cause a fire. The other concern is the 'grounding'. I was
thinking I could address this issue separately and have an electrician
ground certain plugs. (I don't know if that makes sense or not.)
Is there anything else I should be thinking about as to the value of
updating? Is 30 amps too much? Or, needless worry?
I'm having an electrician come in Wednesday to give me an estimate. I'm
sure he'll be of the opinion updating is necessary.
30 years old is just fine, assuming they did a good job when they
installed it. Most houses have electrical systems at least this old, I
High side of what? 20? And how many is "a couple"? It would be normal
to have 30A for an electric range, for a furnace, for an electric
dryer, maybe a few 30A fuses for room air conditioners, etc. As long as
the wiring was adequately sized, there is nothing wrong with 30A fuses.
Same goes for the 20A fuses. There would only be a problem if someone
was mistakenly or stupidly putting 30A or 20A fuses on wires or
circuits designed to carry less, which may or may not be the case (but
you can't tell by just hemming and hawing, you have to go check the
Yup, this is a pain, and may make you want to upgrade to 3-wire
circuits everywhere. On the other hand, by installing a few
strategically placed GFCI outlets, an electrician can safely upgrade
many or most of your other outlets with 3 prong outlets as well. They
would be safe to use, wouldn't require an adapter, wouldn't require any
rewiring in the walls. They would have a little sticker that says "NO
GROUND" or something like that, which can be essentially ignored in
most home scenarios.
Turning off a computer might do little to nothing to protect against,
well, anything. Turning it off at a power strip will give you a little
protection against (small to moderate) surges and spikes. None of that
has anything to do with having a ground or not. If you have a surge
supressor, it may require a ground to be effective, however.
Again, it won't be the fuses that are carrying too much load, it would
be the wires. Don't worry about the fuses being too big, worry about
the wires being too small. Nothing you mentioned so far hints at the
wires being too small (e.g., if you said "my box is filled with 50A
fuses" I would have said "well, someone probably got a box of those off
the back of a truck and stupidly used them instead of buying 15, 20,
and 30A fuses")
30 yrs is not old 70-100 yrs is. If the circuit with the 30a fuse is of
proper wire gauge its fine. I would just have a few outlets replaced
and grounded and have an electrician give the system a check up.
Electricians want work too, so they may needlesly try to sell you a
upgrade. If you realy want to know for your saftey your city electrical
inspector or fire dept will serve you better with an unbiased overview.
For saftey consider a few GFI in bath and kitchen, a mains Surge
Arrestor and Lightning Arrestor. Having your ground professionaly
checked and grounding outlets that have electronics is a good idea.
When the electrician comes ask him to check the wire sizes inside the fuse
box on the 30 and 20 amp fuses. It has been my experience that smaller
fuses get replaced with larger ones to avoid the nuisance of them blowing
from overloads. If that has been the case than you should consider having
some additional circuits installed. If you have an ungrounded system with a
fuse box, it is probably over fifty years old.
As far as upgrading, it is not a bad idea. It would certainly help when it
comes time to sell your house. Many homebuyers are looking at things like
that. Of course a home inspector would pick up on any shortcomings to your
Have you made any other major upgrades to your house such as new windows or
new siding? How about a new kitchen or bathroom? How about an addition?
If you haven't done anything like that, than it may not be worth your while.
The next owner may just knock the house down and build a new one.
Well that's a bad sign, if nothing changed and now it doesn't blow
fuses, and I was going to ask if there were any chance your parents
upgraded when you weren't looking. But below you say you think they
This in itself doesn't mean the house is overloaded. It depends how
much you run at any one time upstairs. I had a whole 6-room, 3-bath
apartment that ran on one 20 amp fuse, uncluding a pretty big
refrierator, a washing machine, and a small room air conditioner. I
would blow that fuse maybe once or twice a year, and I think it was
when the fridge was starting and the AC was starting too, or maybe
when one was running and the other was starting. The apartment came
with a slo-blo fuse, and I continued to use that. That's meant to
keep the fuse from blowing when the fridge is starting.
The apartment didn't have a clothes dryer, an electric stove, or any
I think the most important thing is to find out what gauge the wire is
that comes from each fuse, especially the 30amp fuses.
Second most important thing would be to find out if the boxes the
outlets are in are grounded. You probably have 2-wire BX cable. BX
means that there is a coil of metal wrapped around the two wires and
that coil is supposed to be grounded at the fuse box end, then clampd
to each of the junction boxes. So iiuc it is equivalent to the third
wire in cable that has no metal covering. The metal coil grounds the
box, and if the box is grounded then the metal bracket of the outlet
(receptacle) is grounded and so is the hole in the very center that is
used to attach the wall plate. That's why they have those 3 to 3
prong adaptors with the pigtail or the metal tab, that gets attached
under the center screw.
What I don't know is if it would be legal to put a 3-prong outlet in
such a box, attaching the green grounding screw of the outlet to the
box, if the box is grounded with BX cable. Someone here knows.
As to turning off the computer during lightening, that's what we did
to save the tv in the 50's, but now they have surge protectors that
probably work better even than turning off, because a voltage induced
by lightening can jump the space in an on/off switch. Also a lot of
computers are ruined through the phone line, especially if the phone
lines are on poles. (Mine is underground for the first 200 yards from
my house, but on poles after that.) Remember that DSL comes in on the
phone line too, although maybe DSL modems have surge suppressors???
Another thing that occurs to me is that maybe stereo stuff has gotten
more expensive (I don't buy any.) but computers have gotten cheaper,
and losing one may not be such a big problem. More important is to
back up everything on the computer that doesn't change, and
periodically back up everything that does change. This will protect
you from lightning, hard-drive failure, and burglars, not just
OTOH the price of refrigerators has gone up. I had a friend who I
think lost two fancy telephones, a fancy microwave, and her
refrigerator in one lightning storm. Am I wrong about fridges?
Because surely they cost more than a home computer.
The power of lightning is amazing, and it only has to hit a tree
nearby. OTOH, I think unplugging would still work, better than
turning it off or a surge suppressor. But of course you're not going
to unplug all the time, at least when you're not even home. Does
homeowners insurance cover lightning damage to computers and fridges?
That seems like the last resort.
30A is extremely common. Dryers, A/C units, larger appliances, etc.
Typically you only see 30A in a 2-pole set-up. This means it is a 240V
ciurcuit. (Both hot legs of the service coming in) Definitely check the
wire size versus fuse size. One person metioned that people like to
oversize the fuse if it keeps tripping on them...don't do this. The
breaker and branch circuit wire size are matched according to the code.
(14 awg- 15A , 12 awg- 20A, 10awg- 30A, etc.)
I recommend replacing the panel with a circuit breaker panel. If for no
other reason then you need not buy fuses anymore. This will also
increase the resale value of the home. (Perhaps not by much but some)
In my opinion, the gournding issues is more of a problem when using
larger appliances. Right now, you have no safety ground. If you have a
leakage to the chasis of the appliance...you become the shortest path
to ground...not a pleasant thing to be. Absolutely replace the most
often used receptacles with a GFCI. If the plug are connected together
(One gets fed from the other in a parallel chain) then install one at
the first receptacle so the rest are covered down the line. If you
replace the panel with a CB panel then you can install GFCI breakers
instead. (Also a TVSS to protect your electronics)
I wouldn't worry about your electronics. Computers, TV's, etc. may blow
in an electrical storm whether you have a ground or not. If you have a
TVSS that can't handle the surge then your screwed...even with ground
AND even with your computer off. (Even if your power switch is turned
off, the pc is still physically tied to the circuit. The swicth
typically only break one wire not both)
Charlie S. wrote:
Chances are, the 30's are not the problems. My guess would be that the 20's are
all replacements for the proper 15 amp fuses that the house is wired for. If the
attached to them is not #12, 10, or larger, you are at risk.
The 30 amp fuses are probably for appliances like the water heater.
Somebody installed a load center that uses FUSES 30 years ago! Doubt it,
you must be talking about circuit breakers. If it is a Fuse box, Upgrade it
at your earliest opportunity because it will not pass any inspection where
you upgrade a kitchen, bathroom, bedroom or garage conversion and more.
Some fuse boxes could be upgraded by just replacing the guts and not the
My house is 40 YO and has and had an old style (I forget the brand) breaker
box. I ended up upgrading because AFCI breakers were simply not available
for that box and were required by code in any remodeled bedroom, I also
needed more slots for a new bathroom and kitchen upgrade and outdoor
lighting. A 100A box would have fit in the hole but I went with 200A for
future flexibility and to have plenty of slots for upgrades. The cost
difference at that point was minimal especially since i DIY.
30A is fine if it goes to the dryer on #10 or larger wire
Upgrading the box will not get ground to the receptacles, you would still
need to rip out the walls to replace the wire. Most people do this one room
at a time during major remodeling opportunities. It is not practical to do
it all at once but adding GFCI to each branch will help as they trip much
easier than the branch breakers
Ground is not there to protect your appliances, it is there to protect you.,
Even if grounded, your computer should have a surge supressor. You can get
a whole house surge supressor to fit any of the new style boxes almost any
brand. Simply fits in 2 slots like a 220V breaker
At least if you hire an electrician and there are not too many branch
circuits and the working conditions are favorable.
Its possible as a DIY, I did it, Just looked at it as a big connector on my
house. I spent about $400-$500 on the load center, new mast, new SE
conductors and all new breakers (4 were AFCI and expensive). A few books on
the topic and lots of planning made it come off smoothly.
Add GFCI to critical locations. The receptacles have a ground hole and a
sticker to label that hole as not being connected to ground. These trip
under conditions more likely to be seen when a person gets shocked rather
than a 20A overload. It dosen't actually replace the ground but does
provide a significant improvement in safety for the upgraded locations. Ask
the electrician to elaborate. (these will not trip with a plug in tester,
you need to use the built in button)
Depends only on the wire gague of the branch circuit it is connected to and
the rating of the receptacles it leads to. If they go to regular wall
sockets, replace with 20A or 15A depending on the wire gague. If it goes to
the dryer, this is normal and if you have an electric range it may also go
there but I would expect higher.
ACTUALLY FUSES PROTECT BETTER THAN BREAKERS.
Provided the idiot homeowner doesnt put in a oversized one, or get
shocked changing one.
they are more positive, only age into more sensitive.
but are not convenient when they have opened for whatever reason.
I am interested in other downsides to fuses for a good discussion
I have a friend who uses all 30 amp fuses in his home so they dont
On 14 gauge wiring part knob and tube:( Perhaps the OP has a similiar
The OP may have grounds if its BX cable, in which case he could install
all new 3 prong outlets. this would match the age of the home..........
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