RCD Fault

[alex kane]

Hi Everyone

Been to a customers house today as she said her oven kept 'tripping the electric' in the house they've just moved into. Went round, asked a few questions and it turns out every time they use the cooker, at some point it will trip. She also said all the kitchen sockets went off along with a few other things in the house. So at this point I know the RCD is tripping.

So I unplugged the cooker, did an R1+R2 test and then did a 500V Insulation resistance test. Both results were spot on. At this point I'm still trying not to jump to the conclusion the oven is faulty (It looks pretty expensive). Next, I tested the RCD which controls the cooker circuit and my megger doesn't come back with any results for 1x or 5x. It just reads the maximum reading, which (off the top of my head) was about >300ms and >50ms. I then tested the RCD which controlls the whole board and got the exact same thing.

The CU installed is a wylex 10 way. The main switch has been replaced with an RCD so one of the RCD's controls everything on the board.

I don't do much testing at work but I have passed my AM2 exam so I am comfortable with testing and know what results to get etc. It's just I cant get my head round the fact this RCD keeps tripping but my megger says otherwise? Hopefully someone more experienced can help!

Cheers

 

[Essex_]

What is directing you to the cooker circuit? Rule No. 1. Listen to the client. Then ignore what they said 'happened' and find it for yourself.

 

[LankyWill]

You should inform her that an RCD is not Adequate as a main switch as it provides no OCP! Try a ramp test.

 

[davesparks]

RCD tripping with load connected but not tripping on a test. Can anyone else see the classic symptoms of a N-E fault here?

 

[SJD]

You say you "unplugged" the "cooker", so is this just the oven (and not a whole cooker) that is plugged into a socket circuit? Are you sure it is the RCD that is tripping, or perhaps it is the MCB?

 

[LankyWill]

are you sure the main rcd isnt 100mA and your still testing on 30mA setting

 

[UNG]

You should inform her that an RCD is not Adequate as a main switch as it provides no OCP! Try a ramp test.

OCP???

Please clarify your comment

 

[LankyWill]

OCP???

Please clarify your comment

overcurrent protection

 

[Pete999]

You should inform her that an RCD is not Adequate as a main switch as it provides no OCP! Try a ramp test.

Neither a main switch, provide OCP that is. its the cbs that provide OCP,

 

[LankyWill]

Neither a main switch, provide OCP that is. its the cbs that provide OCP,

I now retreat like a slapped child. Just a little wiser [emoji2]

 

[Pete999]

Hi Everyone

Been to a customers house today as she said her oven kept 'tripping the electric' in the house they've just moved into. Went round, asked a few questions and it turns out every time they use the cooker, at some point it will trip. She also said all the kitchen sockets went off along with a few other things in the house. So at this point I know the RCD is tripping.

So I unplugged the cooker, did an R1+R2 test and then did a 500V Insulation resistance test. Both results were spot on. At this point I'm still trying not to jump to the conclusion the oven is faulty (It looks pretty expensive). Next, I tested the RCD which controls the cooker circuit and my megger doesn't come back with any results for 1x or 5x. It just reads the maximum reading, which (off the top of my head) was about >300ms and >50ms. I then tested the RCD which controlls the whole board and got the exact same thing.

The CU installed is a wylex 10 way. The main switch has been replaced with an RCD so one of the RCD's controls everything on the board.

I don't do much testing at work but I have passed my AM2 exam so I am comfortable with testing and know what results to get etc. It's just I cant get my head round the fact this RCD keeps tripping but my megger says otherwise? Hopefully someone more experienced can help!

Cheers

https://www.youtube.com/watch?v=PfcPDr1SSZ4

When you say R1+R2 and 500v IR test come back spot on, can you tell us what your results were, did you test any of the other circuit? as you say other things were tripping, sounds to me like you either don't know or you are unsure how to test a RCD, I have provided a like for a decent video on RCD testing, I'm not having a go at you Alex, we all have to learn, so don't worry I'm sure you will find a way to sort your customer out, do you have a qualified Electrician who could maybe come along with you and help out, good luck

 

[Pete999]

Hi Everyone

Been to a customers house today as she said her oven kept 'tripping the electric' in the house they've just moved into. Went round, asked a few questions and it turns out every time they use the cooker, at some point it will trip. She also said all the kitchen sockets went off along with a few other things in the house. So at this point I know the RCD is tripping.

So I unplugged the cooker, did an R1+R2 test and then did a 500V Insulation resistance test. Both results were spot on. At this point I'm still trying not to jump to the conclusion the oven is faulty (It looks pretty expensive). Next, I tested the RCD which controls the cooker circuit and my megger doesn't come back with any results for 1x or 5x. It just reads the maximum reading, which (off the top of my head) was about >300ms and >50ms. I then tested the RCD which controlls the whole board and got the exact same thing.

The CU installed is a wylex 10 way. The main switch has been replaced with an RCD so one of the RCD's controls everything on the board.

I don't do much testing at work but I have passed my AM2 exam so I am comfortable with testing and know what results to get etc. It's just I cant get my head round the fact this RCD keeps tripping but my megger says otherwise? Hopefully someone more experienced can help!

Cheers

https://www.youtube.com/watch?v=PfcPDr1SSZ4

When you say R1+R2 and 500v IR test come back spot on, can you tell us what your results were, did you test any of the other circuit?
As you say other things were tripping, sounds to me like you either don't know or you are unsure how to test a RCD.
I have provided a like for a decent video on RCD testing, I'm not having a go at you Alex, we all have to learn, so don't worry I'm sure you will find a way to sort your customer out.
Do you have a qualified Electrician who could maybe come along with you and help out, good luck, perhaps I should have said someone who has more experience than you do on the testing front.

 

[telectrix]

@ OP. your clue is in post #4. davesparks suggests the probable cause.

 

[davesparks]

@ OP. your clue is in post #4. davesparks suggests the probable cause.

Yeah but he's a horrible arrogant bugger who doesn't know what he's talking about

 

[trev]

Yeah but he's a horrible arrogant bugger who doesn't know what he's talking about

How very dare you sir! I have found Dave to be very knowledgeable and only a little arrogant