RCD ramp test

[ianbrookes]

Hi, just tested a fuse board:

1*main switch
lighting circuit
lighting circuit
smoke alarm circuit
-----------------
1*rcd
Oven
Sockets
Sockets
Sockets
Security Alarm
Water Heater
-----------------

RCD failed 1x with ?400ms reading (megger MFT)

performed the ramp test and the RCD tripped at 35ma

any ideas?

thx

 

[telectrix]

test it again. if a RCD has not tripped or been tested with the test button, it may become sticky. i always hit the test button before testing. also, i advise cvlient to test once a month ( test button, )

 

[Sintra]

Try testing the rcd with the loads disconected if you haven't already.

 

[Hawk81]

Or quite simply a faulty RCD

 

[dansk]

test it again. if a RCD has not tripped or been tested with the test button, it may become sticky. i always hit the test button before testing. also, i advise cvlient to test once a month ( test button, )

Are you joking? whats the point in that - just to get the RCD through the test? - never press the test button first, thats the last test you do, your supposed to be testing to make sure it trips in time at any point in time, lets say it was a real life fault and it didnt trip in time.....

 

[mayfair]

Will the rcd not function anyway, I thought that the switch was a secondary thingy (Great Word) Its surely the inards that does the disconection??????

 

[nickblake]

Reg 713-13-01 althought not a specific requirement to BS7671 " in order to test the effectivness of a residual device after installation a series of tests may be applied to check that they are within specification and operate satisfactorily .this test sequence will be in addition to proving that the test button is operational, the effectivness of the test button should be checked after the test sequence" ,

the RCD in question exceeds its rated tripping time on a Ramp test so would deamed to be faulty , unless its a 100ma one of course ,to get an accurate Ramp test reading the test should be carried out twice

having said all that i tend to press the test button twice one before and again after the ammount of RCD's that have gone bang when you press the button is un real especially the series 1 square D ones

shouldnt realy matter when you press the button as it should be done but the consumer every 1/4 bet none are

 

[telectrix]

Are you joking? whats the point in that - just to get the RCD through the test? - never press the test button first, thats the last test you do, your supposed to be testing to make sure it trips in time at any point in time, lets say it was a real life fault and it didnt trip in time.....

ideally, yes, but if an RCD has not tripped or been tested for perhaps a year ot 2, it can get sticky . i agree, the RCD should trip if tested, but then , how can you tell if the client has not tried the test button the day before you came to test. if i'm wrong, then no doubt i will be corrected. it's not the first time and probably won't be the last, but then who on here knows everything?

 

[dansk]

Good answer.