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Hello again bernard it's been a long time, I thought the answer would be something like that. I've just spent quite a long time getting to the bottom of why there is so much confusion over earthing and the issue of whether or not you can get a shock from 230v is about 50% of the problem...

Hi All, Is it possible to receive an electric shock from a 230v mains supply? Or do you have to also be in simultaneous contact with a neutral circuit conductor or an earth conductor?

Hi All, Would anybody care to describe the different functions of 'equipotential bonding conductors' & 'supplementary equipotential bonding conductors' within an earthing system.

Yes it did happen! That's what prompted everyone to take the 16th Edition so seriously, going back to college and everything. mattie, Refusing to pick up an electrical engineering dictionary?

I heard that an Electrician was locked up for manslaughter in the early nineties because an old lady was killed, having received a shock off of an un-bonded metal sink top where she had put a leaky electric kettle!

Why would you claim that local supplementary bonding around a metal sink wasn't required in 1991?

OK, Have you compared the time/current characteristics of a 32 BS 3871 MCB and a piece of 20amp fuse wire? A Dyson, along with many other machines can start at very high currents if they need to. But this current will very quickly drop, it is only the point at which the fuse wire or circuit...

John, Starting current can exceed full load current by quite a considerable amount, which can rupture a fuse that is chosen to accomadate full load current.

No John, 1.45/1.5 is a fusing factor applicable if you have a starting current to consider, when your over-current protection is a fuse. When over-current protection is provided by a circuit breaker, you simply use a B/C/D Type breaker as appropriate. Again this is simple really...

Bernard, As you know the advice right from the beginning has always been that "cabling should not be subjected to small overloads of a long duration", or the cable will be prematurely damaged. 30amp fuse wire will allow for small overloads of a long duration to occur in a domestic 2.5mm T&E...

123, Do you not agree that 13amps is the maximum current rating of a 13amp plug? I will assume that you do, therefore why would you assume that the nominal rating of a fuse carrier is anything more than its' maximum current rating? Have you compared a 32amp BS 3871 circuit breaker to...

Sheds, If you look at your time/current characteristics you will see that 30amp fuse wire doesn't start to be affected by load current until it reaches a value that exceeds any estimate of the current carrying capacity of a 2.5mm T&E ring final circuit. Now compare a 32amp BS 3871 circuit...

Mattie, The IET forum has claimed that the earthing arrangements of the 17th Edition agree with the 16th Edition: 413-02-04 & Table 41C This claim is rubbish, 413-02-04 just gives two alternative solutions to a high loop impedance value (expected to be found in a TT system), when two...

Hi Paul, The fourteenth Edition was approximately when MCB's where invented and when the Regulations were first expanded to their current format, therefore I assume that this was when Table 41C was extended. This was also the Edition where the word radial was first misused!

OK, During a fault of negligable impedance to earth, the cpc will get hotter than the line circuit conductor. This process of heating the cpc takes time, this time will affect the automatic disconnection time of the over-current protective device. Decrease the resistance of the cpc (Table...

Much lower than what?

I believe that the Fourteenth Edition was released in 1966.

Paul, The resistance of all of the other copper cables in the circuit is decreasing whilst the copper cpc is increasing??? John/echoes, Heat costs money!

John/echoes, With the exception of Table 41C, Chapter 41 gives us lists of maximum loop impedance values. If those loop impedance values are met we know that enough current will be allowed to flow in order to automatically disconnect the supply within a specified time(s). Table 41C gives us...

John, The discussion is about allowing enough current to flow in order to automatically disconnect the supply within a given time, which is just about ohms law! V = IR P = (I x I)R