Wylex 80A 30ma rcd - and known issues?

[polo1]

Hi folks,
carrying out an EICR yesterday. Board is a split Wylex (main switch with the rcd covering half the board). All circuits are on the rcd side.
Problem I encountered was trying to take 'no trip' Zs readings, the rcd always trips. The meter (1520) is definitely on the correct setting. Neutrals in the correct bar, TNS supply.
Tried reading both at the rcd and remotely. In normal operation, customer advises that there has been no history of tripping.
Am I missing something obvious, or is it a faulty rcd?

 

[alanl]

It's usual.
You have a load still connected.Could be a PIR, LED lamp, timer.
Anything that may have a circuit board with reference to earth.

 

[Farmelectrics]

surely it shouldn't trip though if you had your d lock on your tester I have a metrel tester I must admit when set on the rcd setting never had any such issues interested to see why it has tripped

 

[Octopus]

Did you ramp test the RCD? IR tests?

 

[polo1]

Never had an issue with connected loads before, is this a "Wyex" issue? Wouldn't ramp test either. 8.5Mo l/n to earth on the whole board. Don't think it's my tester, as I proved it on my own board when I got home.

 

[tony mc]

Hi Polo

Its possible that the 15mA injected for the loop test is pushing the RCD over its limit (with normal leakage with all circuits on RCD)I would try switching off all the other MCB's and test each circuit individually.

Tested loads of Wylex boards and have had this due to above also 6A MCB;s sometimes trip on no trip ZS test !

You say the RCD would not Ramp test I would be looking again at that issue.

Did the RCD test values come out OK ?

 

[Flanders]

As said there could already be earth leakage on the circuits and the test is just pushing it over edge especially if all circuits are on 1 RCD. I have had a RCs tripping with trip lock on due to a load on the circuit, I have found that fridges are the usual course . Try turning all the other circuits off when doing the test

 

[polo1]

Guys, thanks for the feedback and suggestions. I'm back next week so will try dissing loads and do one circuit at a time.
Forgot to mention, couldn't get x1/x5 results either.

 

[Flanders]

Guys, thanks for the feedback and suggestions. I'm back next week so will try dissing loads and do one circuit at a time.
Forgot to mention, couldn't get x1/x5 results either.

If that is the case then i think taking the loads off should solve the problem , You always take the load of when testing RCD trip time , you will see they differ by quite a lot if you have a load on the circuit and can sometimes fail to operate

 

[tony mc]

I take it you tested the RCD at the DB witn no loads connected !

 

[happysteve]

Sorry to ask this, I'm sure you checked... If you get your N and E leads the wrong way round (e.g. where the leads plug into your MFT) then this will cause the RCD to trip every time. I have a Kewtech; it has different sockets for dead tests and live tests, so often a "no trip Zs" is the first live test that uses all 3 leads (for high current Zs, e.g. Ze, and PFC, you join N and E leads together, so it doesn't matter!). The blue and green can look quite similar in reduced light. Just sayin'

I have a Wylex 80A 30mA RCD in exactly the same board you're describing. No issues, test it once a month.