Departurtes

[duncanhead]

You are dangerous please never touch anything electrical again.

NICE PIC!!

 

[RF Lighting]

Wow, thats quite a big hole you're digging

 

[XtraRaptor]

where may it "go bang"?
(with RCDs and RCBOs inplace at the CU), at the local DNO distribution site? The PSC is only 0.56 KA, so with the proposed protection it'll only be a few ms before "cut off" - at "my end", the rated DNO feeds are "good" for several 1000s Amps before something *serious* occurs and very prior to that fault protection will cut in..... copper takes quite a few seconds to "achieve melt down" (and lots of Joules...) , we are not talking about Chernobyl here....

If your cable clamp causes a problem it will not trip any RCD or RCBO within your CU, it will not blow the fuse in the service cutout, as all these devices are after the fault, it would be a big bang, you may not hear it as it would occur down the road somewhere...




Nick.

 

[duncanhead]

And there is a perfectly good sweated earth already there anyway

it's only 6-8 mm2 (estimated), so the extra 10mm2 will do no harm at all, it's to utilise the Ze (in case of an "issue")

It would quite easily clear any fault with out your dangerous and illegal addition.

Oh and there you go again. Trying to sound clever by using technical terms, but getting it oh so wrong

I'm glad of that (in "clearing a fault") but I believe that there is not a maximum cpc size allowed, only a minimum, and as recommended was advised to bond at 16mm2, hence the additional... If you think that I should "limit" a PSC due to DNO "limitations" then thats' another matter..
I'll take that up with EDF then...?

What's dangerous and illegal? - OK yes I could open up the CU and "stick" my fingers in and receive an unpleasant shock, but there is no intention of that, not sure what element is illegal though?

 

[Spark123]

560A is enough to make a big bang! I wouldn't like to be next to a lead cable when the sheath makes contact with the phase. It could be bigger than your PFC as it is upstream from anywhere where you can take a measurement.

Don't know how many seconds at 560A it takes to make lead molten, there's a fair few joules in 560A, (560 x 230 = 128.8kw = 128800 joules per second which is a fair amount of energy!)

As for re-inforcing your Ze, the sweated on one will have been fine. If you didn't trust it then the only 2 things you can legally do are call the DNO and get them to do the upgrade or opt for a TT system.
Or you could accept that prior to the MET, the earthing conductor is nothing to do with you.

 

[RF Lighting]

What's dangerous and illegal?

Attatching a BS951 clamp to a DNO cable.

 

[duncanhead]

Wow, thats quite a big hole you're digging

that's a "nice" pic, is it where you obtain your copper from? !!

 

[RF Lighting]

No, I buy mine from the wholesalers

 

[duncanhead]

where may it "go bang"?
(with RCDs and RCBOs inplace at the CU), at the local DNO distribution site? The PSC is only 0.56 KA, so with the proposed protection it'll only be a few ms before "cut off" - at "my end", the rated DNO feeds are "good" for several 1000s Amps before something *serious* occurs and very prior to that fault protection will cut in..... copper takes quite a few seconds to "achieve melt down" (and lots of Joules...) , we are not talking about Chernobyl here....

If your cable clamp causes a problem it will not trip any RCD or RCBO within your CU, it will not blow the fuse in the service cutout, as all these devices are after the fault, it would be a big bang, you may not hear it as it would occur down the road somewhere...




Nick.

yea, it could cause a fault "upstream" point taken - what do you suggest?
it's all well and good having a 16mm2 cpc, but only a 6mm2 then to to DNO feed, might as well just leave 6 or 8mm2 in place, (the weakest link)..

 

[Spark123]

As I said before, if the earthing conductor isn't yours then there is nothing you can do to it.

 

[duncanhead]

560A is enough to make a big bang! I wouldn't like to be next to a lead cable when the sheath makes contact with the phase. It could be bigger than your PFC as it is upstream from anywhere where you can take a measurement.

Don't know how many seconds at 560A it takes to make lead molten, there's a fair few joules in 560A, (560 x 230 = 128.8kw = 128800 joules per second which is a fair amount of energy!)

As for re-inforcing your Ze, the sweated on one will have been fine. If you didn't trust it then the only 2 things you can legally do are call the DNO and get them to do the upgrade or opt for a TT system.
Or you could accept that prior to the MET, the earthing conductor is nothing to do with you.

All DNOs will give you a Ze of 0.8 Ohms, and as the measured Ze (yesterday) is 0.4 Ohms, I'm quite happy that EDF can "supply" me safely with my "load requirements" with or without diversity...


yea, that sort of "fault" would be big, I admit I'd wouldn't want to test it...
(I've seen swiss army knifes with 9mm (holes) "burnt" into them - with fault protection - on the other hand I've seen/heard a little "click" due to a few ms of phase to cpc short - and no damage, of course the RCD/RCBO has tripped).. thats why RCDs etc are good...

 

[Spark123]

You won't find an RCD protecting the DNO service cable though.
You'll get the full 560A if the cable faults, how the cable behaves is another matter.

 

[duncanhead]

As I said before, if the earthing conductor isn't yours then there is nothing you can do to it.

I'll contact EDF/Siemens tomorrow morning, I have a good contact there and he will advise me accordingly... if it actually means taking off the additional bonding then that's no issue, it only means that the water/gas bonding may take the "extra" - and I don't think that Transco want thier "system" as a cpc....

 

[RF Lighting]

What on earth are you banging on about now?

 

[jockspark]

tell me this is a wind up