fuse box query

[Guvnaar]

What is my fuse box rated at?

Main switch is labelled 80A
The usage meter itself is labelled as 60A
Power company tells me all houses in the street are 55A and the fuse on the outside of the house is 55A
A sparky tells me he thinks it may only be 35A
If it helps the cable between Mains and fuse box that runs thru the roof is a black color 10mm in diameter labelled "OLYMPIC REG 250 VOLT INSULATED NEUTRAL SCREENED"

House was built in 1960, original wiring is the rubber stuff, house has had a recent renovation with safety switch installed.

What is the correct answer?

[NCArcher]

If you still have the neutral screened cable then the house is probably limited to the current rating of that cable which I would guess to be 35A.
If you intend to continue renovations and add additional power points and appliances (air cond, stove, hot plates etc.) then the consumer mains will need to be upgraded by your electrician. It would be a good idea to have the house rewired as well. Get all that rubber insulated cable replaced.
It's generally ok as long as it isn't disturbed but it is well past it's use by date.

[outback]

The answer is 42, the question what is the REAL queation.

[thatirwinfella]

if the 55 amp fuse is the smallest before you reach your fuse board, than your house can draw 55 amps.

the cable may only be rated to x amps, but that doesn't mean the house can't draw more than that... the cable just needs to be protected to x amps.

if the sparky is saying 35 amps, he may have his own reason; there is possible a smaller fuse before the fuse board, or that the cable is now rated to 35 amps and if you want anything more you'll have to upgrade.

i'd get rid of the black rubber wiring as soon as you can afford to, and upgrade the fuseboard to a circuit breaker panel. if you don't have rcd's, get them.

the ratings on your meter and mains switch are only an indicator of how much current draw they can handle and still safely operate.

[Guvnaar]

Great info. thanks so far.

Already have RCD's (40A) and circuit breakers. Although I am wondering if the current setup is a disaster waiting to happen.

Phone Pole -> 55A main fuse -> 35A "Insulated screened main cable" -> 80A Main cct breaker

So let me get this straight - If a device in my house decides to draw 50A for example. The fuse outside and the main cct breaker will happily pass it and fry the main cable which is rated at 35A

Circuit breakers are

Main 80A
Wall oven 16A
RCD 40A
lights 16A
lights 16A
lights 16A
lights 16A
Power 10A
Power 10A

Do I need to get this cable looked at? Reason is I may be installing a aircon capable of drawing 15-17A, already have an electric oven, IXL's, spa, downlights etc.

[Ausyuppy]

Proceed with caution Guvnaar.

I recently moved into my new 1970's home in Brissy. Went and bought four airconditioners after checking the main breaker and seeing that it was 80A, therefor all good.

When the sparky came to install the A/C's he burst my bubble. Some dodgy sparky soldered 10mm cable onto the 6mm cable running through the roof from the street mains to my meter box. There should have only ever been a 40A fuse for the house.

To make the long story short, I ran 16mm cable from the eave of the house to the meter box, then had a sparky come in and connect the new mains cable to the Energex lead in cable and my already "upgraded" switchboard.

Im pretty handy with Electricity as I have worked with it for years in the Navy, however when it comes to the safety of my family and house, its worth taking the advice from the sparky.

Cheers
Steve

[peter_sm]

Our 1950's house had all original box, wiring, fuse etc.

When we bought it, first thing on the list was the fusebox. As we were going to build the garage and required a 40A sub board for what I wanted, the Sparky fitted new fusebox with 80A main fuse etc. The power company came out and fitted new standards cable from pole to house. I don't think I was charged for that part of it.

The power wiring was all replaced. The lighting wiring was left in place as it was still in good condition, and low amperage.

[Sideshow]

One thing to consider is that the fuse carrier at the point of attachment is rated at 55 A, but the fuse inside may be 35 A. This may be what your sparky saw. Where did you get 55 A from? If this is printed on the fuse carrier then that is the maximum fuse that the carrier is rated for, not necessarily what's inside it. If the mains is rated at 35 A, then your fuse is oversize and should be replaced.

Have fun.

[Guvnaar]

One thing to consider is that the fuse carrier at the point of attachment is rated at 55 A, but the fuse inside may be 35 A.
<snip>
Have fun.

Fuse inside is definately 55A - Power co guy took it out and had a look.

I assume the best thing to do is upgrade the mains cable to >55A and change the main circuit breaker to 55A also?.....

What should the main cct breaker rating be changed to

[NCArcher]

The individual circuit breakers will protect the cable and equipment installed. The 80A Main 'breaker' is actually a switch and has no automatic operation. Manual switch on and off only.
You are only likely to blow the supply authority fuses with a major fault in the board or the consumer mains. The 55A SA fuses protect the mains from the connection point to the switchboard and limits the total current that your house can draw.
Your electrician will recommend upgrading the consumer mains to 16mm cable before installing any further outlets or appliances. Shouldn't be too expensive. Leave the main switch as it is.

[Guvnaar]

Ok makes sense.

Looks like my sparky will have to run a 10m length of new mains wire.

This will bump the power rating up from 35A to 55A.

So does this mean I will be able to install a separate circuit for a 15 or 20A inverter (split - reverse cycle) air con without any problems?

[another termite]

You might see the lights dim a little when the air con is running flat out. Why not get a quote on getting three phase run to the house (An air con is a legitmate reason) and seeing as the sparky is aleady doing it anyway. Just think of the tools you could have then...(your meter will have to be changed tho)

[Guvnaar]

I see your point but my budget at this point wont cover it. I just got off the phone with my sparky and he informs me that in order to replace the mains cable the power co will need to be booked as the mains cable is not high enough off the ground and they charge a fortune. The wooden box the meter is housed in needs to be replaced with a metal one as it is located outside.

Does this sound right? I just want to bump the mains up get the 55A capacity to supprt an air-con and leave it at that without spending a fortune...

[NCArcher]

Yes, what he is telling you is correct.
Any work done on the mains or meters means the rest of the installation must be upgraded to conform to current regulations. As you had new CB's I thought that may have already been done.
Not sure if it applies in Vic. but you can use an Accredited Service Provider rather than the Supply Authority. Much cheaper.

[Sideshow]

Unfortunately there's no way out of this one without spending more money than you'd like. As pointed out by NCArcher, the job will snowball quite quickly in order to bring it up to current standards.

As for the supply authority, I think you need to have them come out to identify where your new point of attachment will be (cost to you for the visit) then your electrician does most of the work and finally on the day your new switchboard is energised you need to get the supply authority in at least once, possibly twice (disconnect/reconnect - depends on whether your electrician is authorised to disconnect supply and remove meter).

Great info. thanks so far.

Already have RCD's (40A) and circuit breakers. Although I am wondering if the current setup is a disaster waiting to happen.

Phone Pole -> 55A main fuse -> 35A "Insulated screened main cable" -> 80A Main cct breaker

So let me get this straight - If a device in my house decides to draw 50A for example. The fuse outside and the main cct breaker will happily pass it and fry the main cable which is rated at 35A

Circuit breakers are

Main 80A
Wall oven 16A
RCD 40A
lights 16A
lights 16A
lights 16A
lights 16A
Power 10A
Power 10A

Do I need to get this cable looked at? Reason is I may be installing a aircon capable of drawing 15-17A, already have an electric oven, IXL's, spa, downlights etc.

One thing that I noticed when I had a bit more time to read your post properly is that you have 4 x 16A light circuits and 2x10A power circuits. (a) it's probably the other way round and (b) that's a lot for an old installation with the equipment you specify. With all that reno work it really doesn't make sense that the mains remained original. It suggests to me that the electrical work was done illegally (and therefore dodged the need to have the mains upgraded) and you should probably have it all checked by your electrician anyway. I'd be most worried about the load going through the old mains with the oversized fuse affording a lesser degree of protection.