simulating fault conditions for RCD testing

[another_sparky]

When I perform simulated faults to test an RCD , I would normally bridge the N and E - and this trips the RCD.

However, on the PME System the Neutral to Earth is already linked in the CU.

Anyone any views on the best way to simulate or manufacture a fault to test the RCD on a PME system?

Thanks.

 

[ban-all-sheds]

The best, and only, way is to use an RCD tester. Introducing a N-E short will tell you NOTHING about the trip current or trip time of the device.

I'm amazed that as a sparky you didn't know that..

 

[Big_Spark]

The best, and only, way is to use an RCD tester. Introducing a N-E short will tell you NOTHING about the trip current or trip time of the device.

I'm amazed that as a sparky you didn't know that..

Well there is also the Test Button

Or simply get the apprentice to put his tongue on the live core!!!

 

[another_sparky]

ok. thanks for the reply Ban_
I didnt want to get into a long winded post - so I omitted writing about the testing on a RCD tester - which obviously has to happen,I assumed that you'd know I'd do these tests.

To clarify, I use a Robin KMP 5404 Digital RCD tester.

I was always taught to use not only the tester, but also to 'manufacture' or simulate a fault condition.

On page 80 of the on site guide ( 10.3.8.) it recommends testing the RCD's functionally. ( Not just mechanically pressing the test button)

Also on page 113 (item 13) it says operation of RCD should be tested by simulating a fault condition independant of any test facility....

I've read that faults should be created to 'test the tester'**

So, I've always tested the RCD in 3 ways:

1) Mechanically - by pressing the T button.
2) Digitally - by using a Robin tester
3) Manually - by deliberating bridging the N and E at various points around (for example) sockets in a ring main.


Unless, by doing item (3) I'm just doing a belt and braces approach?

**Edited after I found the item page 113

 

[Big_Spark]

AS..there is no reason to do No3 in all honesty.

If the RCD/RCBO operates by the test button, and the Tester has been calibrated, and the RCD/RCBO operates as it should during testing, then No3 is a pointless exercise and you simply wasting your time..which I presume is money to you

You see, bridging the N/CPC will trigger a functioning RCD/RCBO, however how will it be testing the tester? The devce cannot tell you how quickly it operated, only that it did, you are no wiser as to the accuracy of the readong on the tester than you by NOT doing No3...see my point

 

[another_sparky]

Thanks FWL I appreciate your reply.

The background to my query was asking if others knew a way of making the RCD trip on a PME -but it seems others dont even do the simulated faults.

And yes time is money.

Thanks again - your advice is always useful.

 

[Big_Spark]

Thanks FWL I appreciate your reply.

The background to my query was asking if others knew a way of making the RCD trip on a PME -but it seems others dont even do the simulated faults.

Bridging the N/CPC in say a socket should still cause the RCD/RCBO to operate, it is the supply that is PME, not the circuit.

 

[another_sparky]

sheeesh, I cant' even post the correct page number

I meant, page 133 ( not 113) -item 13

bear with me, I'm old, I can even remember 7.029.

 

[Big_Spark]

AS, if you read the point your quoting properly it says..

FUNCTIONAL TESTING
The operation of RCD's(including RCBO's) shall be tested by simulating a fault condition, independant of any test facility in the device.

That is EXACTLY what the RCD tester does.

 

[another_sparky]

FWL,
I guess I misread ( or missed) in the device and so I've been over testing.

thanks again....