RCD doesnt trip on test.

[Templer]

Hi I have a 6 way split load board located in the shed and served by 10mm SWA. Anything on the unprotected side of the board tests and works fine. However this is not the same for the protected side. I can plug a radio in and the circuit does not trip, but if I use the lawn mower or a drill the RCD trips immediately. In addition, the RCD does not trip when the test button is pushed. I have swapped out the RCD too. Nothing trips on the house board when the RCD in shed trips. All connections are secure in CU. Any ideas where to go next?

 

[saveloy]

Check inside the garage board. I had a fault exactly the same as this last week. RCD would hold but wouldn't work on the test button. Tripped on Zs test.Wouldn,t trip on any RCD tests. Disconnected everything from RCD and it worked perfect. Tripped on test button and all trip times within limits. As soon as busbar and outgoing neutral reconnected fault re appeared. Turned out to be an earth nicked on neutral bar. Once that was sorted all was perfect. Not saying this is definitely your problem but worth a look.

 

[Templer]

Check inside the garage board. I had a fault exactly the same as this last week. RCD would hold but wouldn't work on the test button. Tripped on Zs test.Wouldn,t trip on any RCD tests. Disconnected everything from RCD and it worked perfect. Tripped on test button and all trip times within limits. As soon as busbar and outgoing neutral reconnected fault re appeared. Turned out to be an earth nicked on neutral bar. Once that was sorted all was perfect. Not saying this is definitely your problem but worth a look.

I am tempted to put in another board. This one is an Excel, but I don't want to do all that and the fault still exists. There are benefits to buying a property that has unfinished work, but there are also many issues!

 

[saveloy]

You really need a tester. I wouldn't bother with changing the board until you have tested the RCD to ensure that this is not faulty.

 

[markc123]

Board change could be and probably is pointless.

The test button on the RCD is purely to make sure the RCD is working properly, it's nothing to do with the installation. If it doesn't trip when you press the test button then replace it, if you put in another and it does the same replace it again - they are dodgey RCD's. What make is the RCD? (sorry if already mentioned, just cba to read the full thread) stick a hager RCD in, more money but you get what you pay for and that is quality.

Replace RCD for a fully functioning one, then global IR to see if there are any issues with the installation. Board change probably unnecessary.

 

[Templer]

You really need a tester. I wouldn't bother with changing the board until you have tested the RCD to ensure that this is not faulty.

Which would you recommend?

 

[Templer]

Board change could be and probably is pointless.

The test button on the RCD is purely to make sure the RCD is working properly, it's nothing to do with the installation. If it doesn't trip when you press the test button then replace it, if you put in another and it does the same replace it again - they are dodgey RCD's. What make is the RCD? (sorry if already mentioned, just cba to read the full thread) stick a hager RCD in, more money but you get what you pay for and that is quality.

Replace RCD for a fully functioning one, then global IR to see if there are any issues with the installation. Board change probably unnecessary.

Hi Mark, thanks for the reply. The RCD is the same as board, Excel.

 

[markc123]

If you've bought a replacement Excel RCD and it doesn't trip when you press the T button, send it back.

When im doing installations, unless the client is on a poor budget i always fit either hager or Mk - there is a reason why some RCD's are 10x the price of others, even though they do the exact same thing lol.

 

[Templer]

If you've bought a replacement Excel RCD and it doesn't trip when you press the T button, send it back.

When im doing installations, unless the client is on a poor budget i always fit either hager or Mk - there is a reason why some RCD's are 10x the price of others, even though they do the exact same thing lol.

Will a hager or MK fit into an Excel board?

 

[markc123]

Will a hager or MK fit into an Excel board?

Hager are pretty good at being universal, however i wouldn't like to advise mate - never used Excel.

Do you have a specialist wholesaler near you that could advise you?

 

[Templer]

Hager are pretty good at being universal, however i wouldn't like to advise mate - never used Excel.

Do you have a specialist wholesaler near you that could advise you?

I will pop in tomorrow and ask the question. I think the time has come to invest in a tester

 

[FAA Greenie]

Templar - have a think about what happens when you press that test button.

I suspect you have a N-E fault. Your radio probably doesn't even draw 30mA so wouldn't trip it anyway.

Try testing the T button on the RCD with ALL the MCBs tripped and circuit neutrals disconnected - I bet it works.


If you have a short N-E in one of the circuits this board supplies, the test current generated when you press the button will be divided through the actual fault path, and also the artificial one provided by the test button. The odds are that the device will not trip because the required trip current will not met.

Worth trying.....

 

[Templer]

Templar - have a think about what happens when you press that test button.

I suspect you have a N-E fault. Your radio probably doesn't even draw 30mA so wouldn't trip it anyway.

Try testing the T button on the RCD with ALL the MCBs tripped - I bet it works.


If you have a short N-E in one of the circuits this board supplies, the test current generated when you press the button will be divided through the actual fault path, and also the artificial one provided by the test button. The odds are that the device will not trip because the required trip current will not met.

Worth trying.....

Interesting... I have removed all circuits from the board and it still does not trip on test.

 

[FAA Greenie]

Sorry buddy, I edited the post after I read it through again, did you disconnect final circuit neutrals too?

 

[Templer]

Sorry buddy, I edited the post after I read it through again, did you disconnect final circuit neutrals too?

Hi board has no circuits on it apart from a single socket on a lead and the RCD does not trip on test but trips as soon as load is placed on it. Could I have a N-E fault on the SWA? If so, would it not trip the RCD in the house CU which feeds it?

 

[FAA Greenie]

Hmmmmnnnn

See, if you also have the RCD in the main board supplying, you are still dividing the test current between two RCDs. It's a difficult one.

You really need to be able to IR test.

Do you have an unprotected way on the main board to connect the external board to?