Can someone let me know the science behind this please. I’ve been told that if there is a fault on a circuit the ZS values in the regs are there to give ADS in a time that is not going to cause considerable harm. My question is if disconnecting times don’t comply what is the dangers that arise I know it’s physics but have seen marshalling bars carrying current through earthing conductors all day and we don’t get a shock of them. Thank you for you help in advance guys just want to clear up some unanswered questions.
If you touch a faulty appliance, so the case is live due to a fault, in fact it would have to be 2 faults. Broken earth and metal case live.
Not entirely - even with a perfectly intact earth conductor (c.p.c.) the voltage on the appliance case will rise up to a hazardous voltage during the time it takes the protective device to operate - which hopefully is quick enough to prevent death, but isn't always (especially if Zs is too high).
If you touch a faulty appliance, so the case is live due to a fault, in fact it would have to be 2 faults. Broken earth and metal case live.
Not entirely - even with a perfectly intact earth conductor (c.p.c.) the voltage on the appliance case will rise up to a hazardous voltage during the time it takes the protective device to operate - which hopefully is quick enough to prevent death, but isn't always (especially if Zs is too high).
