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Really.
Is the maths or reference to standards I present somehow questionable because of the lack of current equipment that I personally own? Is the personal equipment I own related to my knowledge of safety regulations or a desire to not see people encouraged to ignore them? No. Take your FUD and shove it.
It's fine when you question my statements and ask me to show data to back up my claims. Guessing you were not expecting me to actually follow through. Now that I have and the roles have changed you start whining and telling me to shove it.
The meme below comes to mind...
for equipment marked with measurement category I, a warning shall be given not to use the equipment for measurements within measurement categories II, III and IV
Measurement category I is for measurements performed on circuits not directly connected to MAINS
Quote from: IanB on April 29, 2023, 06:42:22 pmFair enough. Which is why I would curious if any UK based electricians here could indicate what kind of prospective fault current would be measured at a typical UK 13 A wall socket? (It would be a range, obviously, but typical/min/max would be interesting.)Wikipedia says typical UK ring circuits have 30A fuses and 2.5mm2 cable.
Fair enough. Which is why I would curious if any UK based electricians here could indicate what kind of prospective fault current would be measured at a typical UK 13 A wall socket? (It would be a range, obviously, but typical/min/max would be interesting.)
Wikipedia needs editing... what a surprise! Any installation still using fuses would for sure be a Code 2 on an EICR, maybe a Code 1 if the sparky is in a bad mood (yes, there's some wiggle room). Most are going to be MCBs at the least, or RCDs or RCBOs. In any case, for domestic installs they'll be 32A type B, with a 6kA breaking capacity.The 2.5mm2 T+E has a CPC CSA of 1.5mm2, and in a ring of course there's two paths back to the board (barring fault conditions).Radials (for socket outlets) are in 4mm2 which also has a 1.5mm2 CPC (used to be 2.5mm2, but hey, cost cutting), and will be protected by a 20A type B MCB/RCD/RCBO.
Quote from: AVGresponding on April 30, 2023, 05:27:08 amWikipedia needs editing... what a surprise! Any installation still using fuses would for sure be a Code 2 on an EICR, maybe a Code 1 if the sparky is in a bad mood (yes, there's some wiggle room). Most are going to be MCBs at the least, or RCDs or RCBOs. In any case, for domestic installs they'll be 32A type B, with a 6kA breaking capacity.The 2.5mm2 T+E has a CPC CSA of 1.5mm2, and in a ring of course there's two paths back to the board (barring fault conditions).Radials (for socket outlets) are in 4mm2 which also has a 1.5mm2 CPC (used to be 2.5mm2, but hey, cost cutting), and will be protected by a 20A type B MCB/RCD/RCBO.What it actually says is: " They are generally wired with 2.5 mm2 cable and protected by a 30 A fuse, an older 30 A circuit breaker, or a European harmonised 32 A circuit breaker. Sometimes 4 mm2 cable is used if very long cable runs"But don't let your anti-Wikipedia bias get in your way.
4mm2 can be used for particularly long runs, but this is not ideal, and would be unlikely to be necessary in a domestic setting, and would be discouraged in any case, due to the negative impact on tripping times. I have seen 6mm2 used on a 20A radial socket circuit; it barely passed muster under testing.
I have seen 6mm2 used on a 20A radial socket circuit; it barely passed muster under testing
Quote from: AVGresponding on April 30, 2023, 01:00:36 pm4mm2 can be used for particularly long runs, but this is not ideal, and would be unlikely to be necessary in a domestic setting, and would be discouraged in any case, due to the negative impact on tripping times. I have seen 6mm2 used on a 20A radial socket circuit; it barely passed muster under testing.How and why does cable size affect tripping times? For example, a 12 m run of 6 mm2 is going to have the same resistance and voltage drop as an 8 m run of 4 mm2 or a 5 m run of 2.5 mm2. Run lengths are going to vary a lot between a large house and a small shed.
Quote I have seen 6mm2 used on a 20A radial socket circuit; it barely passed muster under testinghow come? the R1 R2 for 6mm is going to be lower than the same length of a bit of 2.5/1.5,meaning your fault current will be higher leading to a faster disconnection time,the only failure i can think of is the fault current being to high for the protective device
You're thinking in terms of DC resistance; this is an AC circuit...
Quote from: AVGresponding on April 30, 2023, 06:25:00 pmYou're thinking in terms of DC resistance; this is an AC circuit...The calculations for 50/60 Hz AC are the same as for DC where resistance, voltage drop and maximum fault currents are concerned.