4 30mA RCDs in series!

[Richard Burns]

I have just fixed a fault today on a 2 year old install where there was a 30mA RCD from the tails feeding to a remote twin 30mA RCD board feeding a 30mA RCD garage board in an outside office feeding another 30mA RCD garage board in another shed!

Discrimination whats that?

I did not test the RCDs, sorry

Oh yes and the second board was for part of an extension to the house and was a TT board, sort of, some confusion over whether the steel wire armour should actually go into the gland.

That is the most RCDs in series that I have seen so far:whatchutalkingabout.
Don't you just love it!

 

[telectrix]

it's called backing up the back up of the back up, or belt, braces, a bit of string and 2 pairs of underpants

 

[Ziggy Sparks]

Isn't it amazing the amount of so called sparks that can't tell a 0.03 and a 0.3mA apart....

 

[Robotstar5]

Isn't it amazing the amount of so called sparks that can't tell a 0.03 and a 0.3mA apart....

Decimal point blindness?

 

[nickblake]

Did A PIR last year that had a main board that fed another main board then out of that fed a board to ground floor then an board to 2nd floor then a board to third floor then a board to 4 floor all with main switch RCD's and almost a week later i managed to sort it all out as it should be , and the guy told the lady of the house that because it had an RCD it didnt need bonding to water and gas , try explaining that it had to be put in 12 months after it had been rewired

 

[Guitarist]

Did A PIR last year that had a main board that fed another main board then out of that fed a board to ground floor then an board to 2nd floor then a board to third floor then a board to 4 floor all with main switch RCD's and almost a week later i managed to sort it all out as it should be , and the guy told the lady of the house that because it had an RCD it didnt need bonding to water and gas , try explaining that it had to be put in 12 months after it had been rewired

Amazing how many people think that an RCD eliminates the need for anything else!
Earthing, MCB's, insulation....who needs them when you have an RCD?

 

[KFH]

Did some work on a farm house. The supply from the barn to the house had recently been updated by someone else. Tested 30mA RCD in house, did not trip but supply went off. Asked 80 year old invalid female customer where the supply came in. Had to climb into a barn (3 ft high entrance) climb a set of rickety stairs to an upper barn, walk across a very rotten floor to find another 30mA RCD which had tripped. What chance would the customer have stood trying to fix it, especially in the dark? Unfortunately due to complicated inheritance problems no one will pay me to fix it. Gave her a report to sent to trustees but am not holding my breath.

I wonder what percentage of electricians do not understand discrimination on RCDs or the problems that occur when there is none.

 

[Spark1979]

Lots, see it all the time with a simple garage db let alone something bigger, stick a 30ma RCD on it it'll be ok! Big problem not is Electrical Trainee thinks stick it on an RCD and it'll be alright that's what their being taught. 17 th edition has back fired IMHO!!

 

[Guitarist]

Most of the time it's really not a big problem if we're honest. RCD trips in the house rather than the garage and it's quickly sorted. The situation KFH describes is the sort of mess which is unacceptable.