Fuse Box

johndoe99

i had an electrician around today as the cord/box that activate my electrical shower was damaged and needed replacing.

When asked to see the fuse box so he could kill the power, he noticed, in his words; the previous electrician that had installed the electrics for the shower 12 months previous had in fact used the wrong fuse (the 1st image):



and that this was very dangerous, so he replaced it with the one below:



To any electricians reading this, how Safe / Unsafe was this really ?

Thanks.

M cebee

unsafe- assuming it wasn't fed through a 63amp rcd at all

you 32amp rcbo may be undersized though- depending on the shower

ShamFeen

FIRST of all, how old is the breaker to the left??? Yes he is right in his theory although I couldn't properly comment without seeing your installation. The old breaker is an Miniature Circuit Breaker, a modern take on the old fuses but you can reset after it trips. The one he replaced it with is an R.C.B.O which is a combined M.C.B and R.C.D (the trip on your sockets) This is better as it trips on earth leakage as well as short circuit and overload. It's possible that the shower used the old M.C.B for short circuit and was on the same R.C.D as the sockets, but this could lead to nuisance tripping of the sockets if there was any problems with the shower.

ShamFeen

you 32amp rcbo may be undersized though- depending on the shower[/QUOTE]


Not neccessarily if it's a 6sq feeding the shower as this should be protected by a max 32a breaker. If it's 10sq then yes you're bang on.

M cebee

ShamFeen wrote: »

you 32amp rcbo may be undersized though- depending on the shower

Not neccessarily if it's a 6sq feeding the shower as this should be protected by a max 32a breaker. If it's 10sq then yes you're bang on.[/QUOTE]

ya i said maybe :cool:

ShamFeen

AAAAAAHHHHHHHHH apologies oh wise one!!

Bruthal

Maybe the 40amp MCB was connected through the sockets RCD or something. We dont really know just by looking at them photos.

M cebee

ya - it wouldn't be 'very dangerous' then:D

but still bad practice and doesn't comply with wiring rules

Bruthal

M cebee wrote: »

ya - it wouldn't be 'very dangerous' then:D

but still bad practice and doesn't comply with wiring rules

I know yea. I actually did it in my house a few years back, eventually intending to get an RCBO, someday i will

bertie1

Looking at the grime on the mcb next to the 40A b rated mcb , it looks like its an older board , the 40 A mcb through the rcd for the sockets would have complied with the regs then .

johndoe99

bertie1 wrote: »

Looking at the grime on the mcb next to the 40A b rated mcb , it looks like its an older board , the 40 A mcb through the rcd for the sockets would have complied with the regs then .

dont know what u mean, i know nothing about the electrics, but if its any help the house is 20 years old, but the shower and the socket for it were put in 2 years ago
.

.G.

johndoe99 wrote: »

dont know what u mean, i know nothing about the electrics, but if its any help the house is 20 years old, but the shower and the socket for it were put in 2 years ago
.

Take a photo of the full fuseboard and post in here.the placing of the rcbo if it is in the same position as the replaced 40A MCB will give us a better idea of what the previous electrician might have done.

That said if it was done 2 years ago then it should have been done the way your new electrician has done it now,but thats not to say the old way was dangerous,it was not if protected by the socket RCD as mentioned in previous replies

johndoe99

M cebee

so prob 'bad practice' but not very dangerous


is it a 40 or 63

.G.

M cebee wrote: »

so prob 'bad practice' but not very dangerous

Indeed

Buford T Justice

Looks like the old MCB for the shower was wired via the 63A RCBO, and the new one is a direct feed to its own RCBO

Bruthal

Fingers McGee wrote: »

Looks like the old MCB for the shower was wired via the 63A RCBO, and the new one is a direct feed to its own RCBO

Looks like the old MCB for the shower was wired via the 63A RCD you mean?

Anyway OP, it looks like the original shower MCB was using the sockets RCD so it was not dangerous if that was the case. I think this was acceptable a few years back once the sockets RCD had a breaking capacity of 63 amps. I have my shower done this way, although always used seperate RCD/MCB or RCBO for everyone elses i installed.

johndoe99

thanks for all your input lads.

Buford T Justice

robbie7730 wrote: »

Looks like the old MCB for the shower was wired via the 63A RCD you mean?

Of Course

aido 1976

The original breakers in the board are at least 10-12 years old.

And the 40a MCB that the the OP said was installed about 12 months ago, is infact about 5-6 years old. Think the installer must have had it kicking around his van for a while.

Electricman999

johndoe99 wrote: »

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I see you have a Separate 63A switch and fuse unit these can be troublesome as the link between the switch & fuse has a tendency to burn out and melt your cover of your mcc board as well as destroy the breakers closest to it.
I would strongly recommend getting your Electrician back to replace the old 63A switch fuse unit with a 63 Amp S/P Neozed Switch Fuse

2011

I see you have a Separate 63A switch and fuse unit these can be troublesome as the link between the switch & fuse has a tendency to burn out and melt your cover of your mcc board as well as destroy the breakers closest to it.
I would strongly recommend getting your Electrician back to replace the old 63A switch fuse unit with a 63 Amp S/P Neozed Switch Fuse

I would agree. I have seen a few of these fail. The chances of failure increase dramatically when large loads are connected to a distribution board such as an instantaneous type shower (like a Triton T90).

The combined switch fuse unit also frees up more space in the board.

2011

it looks like the original shower MCB was using the sockets RCD so it was not dangerous if that was the case. I think this was acceptable a few years back

Yes, this was permitted in the past.

M cebee

the link from switch to fuse does seem to give a fair bit of trouble alright

ShamFeen

aido 1976 wrote: »

The original breakers in the board are at least 10-12 years old.

And the 40a MCB that the the OP said was installed about 12 months ago, is infact about 5-6 years old. Think the installer must have had it kicking around his van for a while.

There are some wholesalers in Cork where that old type of M.C.B are still available. Even though the newer ones are in, I presume it's because the 40 Amp wouldn't be as popular as 20, 10, or 32 Amp. Also people use R.C.B.Os for showers etc.