what do you call this fuse?

I came across this at a customer's place.



Semi - enclosed ceramic but it pre-dates BS3036. The iron break-out (yes it is is bonded..) enclosure is "Callender" branded and dates from when the house was built (1930's).

I will pull the fuse next visit and measure/check the wire diameter. I am expecting 60A but not sure. The Callender brand ceramic holder says "Carry 30, 60 blow" but that will be pretty meaningless. The customer says the fuse blew some years ago and was replaced. (I have checked - it does contain a fuse and not a nail.

I could replace the wire next visit with known 60A so I can correctly document it ? - But that belongs to DNO and not my bit to alter. Would you do this - or just rely on the Vernier & 533.1.1.3 ? DNO seemed happy with the fuse (by visual inspection only isofar as there was one!) without even checking it - see later.

60 A is adequate for the customer (with a little constructive diversity) and is limited to that anyway by 16mm tails to the meter.

I shall probably assume the worst-case for short-circuit capacity of newer BS3036 S1A type (ie 1KA). - This still covers me for the measured PFC.

Installation is TNS, lead sheathed supply cable with double layer spiral steel banding.

I had the DNO round before touching anything to provide the installation with a new MET clamped to the lead sheath since first thing I did was measure 8 Ohms Ze. (There was no MET, and a teeny single strand Cu wire earthing conductor wrapped round the sheath and probably corroded) - Now a better figure Ze (0.33) from which to begin.

I was very surprised that DNO guy said they have changed their policy recently, and now they won't replace break-outs like this even if they are 80 years old.

But what type of fuse do I record? (For supply protective device in EIC) ? I could just put "semi-enclosed fuse", 60A (TBC after inspection), and assume 1KA rated short circuit capacity. - Would that be reasonable?

It's still classed as BS 3036 protection, as are all rewireable fuses.... By the way the arrangement shown in your photo say's it's TN-S not TNC-S...

The DNO shouldn't of been happy with this service cut-out, in fact they have been instructed to replace all such iron clad rewireable service heads nationwide by 2011, which they haven't complied with.

To be honest I don't think there is a lot more you can really do, but cater for worse case here. Your take on it being S1A and 1Ka is pretty fair.

Not sure what you mean by it being an TNC? it is either a TN-C-S or a TN-S and by the looks of things it is certainly not a TN-C-S. What was your Ze reading by the way?

What was your Ze reading by the way?

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Stated in the OP's post mate!! lol!!

first thing I did was measure 8 Ohms Ze. (There was no MET, and a teeny single strand Cu wire earthing conductor wrapped round the sheath and probably corroded) - Now a better figure Ze (0.33) from which to begin.

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Yep, first thing you need to do on your next visit home, is a trip to SpecSavers!! lol!!

Hmmmm this obvious lack of ability to read things is a worry now mate ..................lol I can't play the age card well not with you Col

malcolmsanford said:

Hmmmm this obvious lack of ability to read things is a worry now mate ..................lol I can't play the age card well not with you Col

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I have the same problem at times, ...not reading the post i'm replying to, too closely!! And it has unfortunately, nothing to do with my glasses!! lol!!

ooops typo guys sorry I did mean TNS when I wrote it. Corrected now to save future confusions..

Thanks for the comments.

It's interesting to hear from Engineer 54:

The DNO shouldn't of been happy with this service cut-out, in fact they have been instructed to replace all such iron clad rewireable service heads nationwide by 2011, which they haven't complied with.

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1Justin said:

ooops typo guys sorry I did mean TNS when I wrote it. Corrected now to save future confusions..

Thanks for the comments.

It's interesting to hear from Engineer 54:

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Too late I'm afraid
I have had to meticulously read each sentence to find the offending words and failed but all has now been revealed lol

fred? ok maybe not but i think it looks like a fred

pre-empted by ezzz. was going to say that i once had a fuse like that and called it albert, just because it looked victorian.

malcolmsanford said:

Hmmmm this obvious lack of ability to read things is a worry now mate ..................lol I can't play the age card well not with you Col

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You definately should go to specsavers if there is a branch in lovely Riyadh

ring up DNO. they will get the head changed pretty quickly free of charge.
and they usually will convert to TNC.

its a old fuse lol,

No ability to seal it off either

I am happy to don my big yellow gloves and pull a fuse but I personally would leave that, I'd worry it would break in my hand. I'd be much happier if it was changed, are you sure you cant smell what you think is burning lol, and while they are there...