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michufc

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hi in your experience what would cause a rcd not to trip in 0.4s at 1 x test

cheers mike
 
J

JulesHurley

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  • #2
Mike,

Im not sure I understand your question, may need more information.

As far as I'm aware, RCDs do not have to trip within 40ms @ 100% test. I was always had the understanding that the trips are;
No trip @ 50% or 1/2 rated
<200ms @100% or 1 x rated
<40ms @500% or 5 x rated

But, I was once told that RCDs can be slow in cold weather - it may be a myth, or someone taking the pi**.
 
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WarrenG

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  • #3
Yes Jules your right the 40ms is for 5x Rating

1x rating should trip in <200 ms for BS 4293
1x rating should trip in <300 fms for BS EN61008 or BS EN61009

michufc - onsite guide P91-92
 
S

Spudnik

  • Thread Starter Thread Starter
  • #4
hi in your experience what would cause a rcd not to trip in 0.4s at 1 x test

cheers mike
Sometimes depends on how old RCD is.

if its a few years then it has been known in the past that some can 'stick' if the test button hasnt been used enough.

This is the reason why they have them.

Alternatively it could be just faulty, new or old.
 
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WarrenG

  • Thread Starter Thread Starter
  • #5
If its new and you have run tests on it and the test results do not meet the requirements then you may have a faulty switch?

It does happen and usually gets us running around like headless chickens trying to fault find.

You haven't said what brand it is but you would be surprised with some of the brands that have had to recall. Thats without the counterfit stuff that floats around.
 
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WarrenG

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  • #7
Assuming that the test is being carried out correctly? :confused:
 
G

Guest123

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  • #8
Hi.

At th'end o't day if your not sure and think it may be faulty also, for your own peace of mind change the RCD.

But like the lads have said 1x does not need to disconnect in under 0.4s.

Cheers:D.
 
C

Chappers

  • Thread Starter Thread Starter
  • #9
I've wondered about this: the device must disconnect in under 0.4 seconds, often put as 40ms. Thing is, 40 milliseconds is 0.04 seconds, so surely it should be in under 400ms not 40ms?

Where have I gone wrong?
 
M

maddfridge

  • Thread Starter Thread Starter
  • #10
hi in your experience what would cause a rcd not to trip in 0.4s at 1 x test

cheers mike

Hi there

could your rcd be on the supply side and not the load side ?

I tried to test a 30ma rcd ( before consumer unit) on a portacabin and whatever tester we used it would not trip it had been installed with incoming at the bottom of the rcd we tested at the top going out to the distboard but it all just was enclosed in the fabric of the building..functional still worked though

so it is possible to test on the supply side and think the rcd is shot. or sticking while the function works :)

cheers
 
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