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Discuss Crabtree RCCB's in the Commercial Electrical Advice area at ElectriciansForums.net

T

Torris

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Hi
This is my first time on a forum and this is my problem.

I carried out some testing on a domestic premises, the consumer unit main switch is a Crabtree RCCB 2 pole rated at 80A with 100mA trip.
I carried out an RCD test at a random socket with my tester set to 100mA and tested on both cycles on 1/2I with no trip 1I with no trip and 5I with a trip at 6.3ms strangely it is the first time i have worked on a RCCB. My first instinct is to condem the RCCB, but as Im not 100% sure could anyone give there opinion, Am I missing something?

Thanks in advance

Torris
 
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T

TonyM58

  • Thread Starter Thread Starter
  • #2
Another forum, i saw a similar problem. When the guy plugged a class II radio into the circuit and retested at a different socket the RCD tests were ok! (dont know if was crabtree)

Is your tests the same at each socket, and what results do you get if you go directly to the output of the RCCB?

Oh, and the other thing, i believe i am right in saying the x5 IdeltaN test is ONLY applicable at 30mA or less, so you should not be testing a 100mA on x5 anyway!
 
E

EasyFox

  • Thread Starter Thread Starter
  • #3
Firstly no 5x test on 100mA (the fluke wont even let you do the test)

Secondly a 100mA rccb/rcd shouldnt be used to reduce the risk of electric shock (412-06-02) as it doesnt offer protection against direct contact unlike a 30mA would so shouldnt be used for socket circuits.

100mA & higher are normally used for protection against fire in the event of earth leakage, or used on TT systems as main switch (if rcbo's are used on individual circuits) or the 100mA S type time delay are used on split load boards.

So in answer to your question I'd check you are testing at correct range (S type or not) then do as Tont58 said test the rccb in isolation from all circuits, if it fails again swap it out.
 
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R

Riggs

  • Thread Starter Thread Starter
  • #4
Be careful on the split load crabtree boards as usually the 100ma RCD is a timed delay type as EasyFox stated. A normal RCD tester will not let you carry out the tests. You will require a time delay tester for the RCD tripping times.
 
M

Minky

  • Thread Starter Thread Starter
  • #5
RE:-Crabtree RCCB's,i came across a 80A/30mA RCD yesterday and found it failed the 30mA test at 1x and 5x,the device would not function when the test button was pressed,but after resetting it,it would let current flow.The type was a StarBreaker,and was part of a split-load kit.Have to swap the RCD,and would certainly not recommend this type of board.
 

ian.settle1

-
Mentor
Arms
Another forum, i saw a similar problem. When the guy plugged a class II radio into the circuit and retested at a different socket the RCD tests were ok! (dont know if was crabtree)

Is your tests the same at each socket, and what results do you get if you go directly to the output of the RCCB?

Oh, and the other thing, i believe i am right in saying the x5 IdeltaN test is ONLY applicable at 30mA or less, so you should not be testing a 100mA on x5 anyway!
Tony

You are correct you only do the X5 test on RCD/RCBO's up to and including 30mA when used for supplementry protection (Reg 412-06-02);)
 
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