Can no longer have an 80amp supply?!

[oldsparkyuk]

It's because the company puts a 100 Amp fuse in for safety of the supply system, its your consumer unit fuses that protect YOUR system, your trying to make more of this than you should, let them look after themselves and you your system.

 

[JohnW2]

It's because the company puts a 100 Amp fuse in for safety of the supply system, its your consumer unit fuses that protect YOUR system, your trying to make more of this than you should, let them look after themselves and you your system.

I think that's what he is doing, in as much as he doesn't feel that his (presumably) 16mm² meter tails (to his CUs) would be adequately protected by 'their' 100A fuse. ... even though I can't say that it's an issue that I could personally get very excited about!

Kind Regards, John

 

[oldsparkyuk]

Worrying about nothing, if he updates his CU he will update the tails, as they have been fitted to the standard that was right at the time nothing has changed, except the new regs and they change all the time just because they have doesn't mean that anything is wrong with the old system does it. I'll say it again the 100 amp company fuse is there for them not him, the unit fuses are for him .

 

[EFLImpudence]

Yes, but it is easily possible to have an installation which could draw more current than the tails can handle.

I don't think that is the case in this thread but the installation tails should be protected (somehow) from current exceeding their rating.

 

[JohnW2]

Worrying about nothing ...

I totally agree, but, for someone who is concerned ....

I'll say it again the 100 amp company fuse is there for them not him, the unit fuses are for him .

So what do you feel is protecting his meter tails? If not the company fuse, and ignoring the possibility of a fault in the tails, it could only be the combined downstream OPDs - which will very probably add up to considerably more than 100A.

Kind Regards, John

 

[oldsparkyuk]

OK lets just put the poor mans nightmares to bed, its safe as it is, we all know the regs have changed ( not always for the better ) but why do we on here make a mountain out of a mole hill, when someone asked a simple question only go on about how bad things can get or more often go off subject?

 

[ban-all-sheds]

I think that's what he is doing, in as much as he doesn't feel that his (presumably) 16mm² meter tails (to his CUs) would be adequately protected by 'their' 100A fuse.

And the rating of 16mm² conductors in free air is...... ?

 

[JohnW2]

OK lets just put the poor mans nightmares to bed, its safe as it is, we all know the regs have changed ( not always for the better ) but why do we on here make a mountain out of a mole hill, when someone asked a simple question only go on about how bad things can get or more often go off subject?

It was the OP himself who, in the very first post in this thread, expressed the view that a change in the cutout fuse to 100A would require him to upgrade his meter tails to 25mm² - which, for strict BS7671 compliance, is probably true.

Practices may have changed, but I'm not so sure about the regs - was it ever compliant to have a 16mm² cable protected by a 100A fuse?

Kind Regards, John

 

[JohnW2]

And the rating of 16mm² conductors in free air is...... ?

94A, I believe - which I also believe is less than 100A.

However, I strongly suspect that everyone (other than any lurking Jobsworths amongst us) agrees that the OP is unnecessarily 'concerned'.

Kind Regards, John

 

[ban-all-sheds]

was it ever compliant to have a 16mm² cable protected by a 100A fuse?

It always was, and still is, if the cable type, installation method and other relevant environmental factors mean that it can safely carry 100A.

 

[Guitarguy]

I can't speak for the DNO in Jersey as I don't know their regs/ procedures as they may differ ours (ssepd.)
That cutout and tails uo to the meter are rated to provide 100a max load, the service cable will most likely be from the looks of it .0225 2c PILCSTA which is got for 100a.
Not sure why they are doing away with 80a fuses, maybe they just don't want to complicate things too much, we don't generally install them on new supplies but suppliers like British Gas do when they fit meters.
I have seen many many installations mainly from the 80's and before running with 16mm tails on 100a fuses both single and 3 phase with no problems. It may not be in keeping with the regs anymore because as far as I know 16mm tail is rated to around 83a in normal circumstances whether this is right or wrong it happens.
It would be a good idea to upgrade it to 25mm as it will get warm if heavily loaded to its max capacity.
Hope it helps

 

[ban-all-sheds]

94A, I believe - which I also believe is less than 100A.

Is that for single-core, or 2-core?

Extrapolating 4D1A gets me 99.8875A....

 

[JohnW2]

Is that for single-core, or 2-core?

Good point.

Extrapolating 4D1A gets me 99.8875A....

It depends on what one extrapolates from - I got 99.21A ... but still <100

I think we are agreed that this is all silly. I have never personally used, and have rarely seen, short runs of 25mm² to a CU. I do have some 25mm² in my house, but that is for some very long distributions circuits, and has been done because of impedance (i.e. VD and EFLI) considerations, not CCC.

Kind Regards, John

 

[ban-all-sheds]

It depends on what one extrapolates from

131x61/80 (I know - that does not take into account the circumference of the conductor).

(VD and EFLI)

Good God! - Has he caught the Portuguese Disease already?

 

[JohnW2]

131x61/80 (I know - that does not take into account the circumference of the conductor).

Why, I wonder, did you extrapolate on the basis of the Method A figures? Mind you, Method C figures give almost the same answer - 131 x 87 / 114 (=99.97).

Kind Regards, John