RCD test

[tigerpaul]

Hello,

Please can you help settle an argument I've got going on at work at the mo. It is about testing RCD's.

I say you can test RCDs/RCBOs at the device itself. I just place my leads on the load side of the device and perform the test.

My colleague says you need to go to the end of line to perform the test. His reason for this is, "you are then testing through the whole of the circuit". I've no idea what he's going on about but he is adamant.

As far as I can see, the whole of the circuit has already been tested with your continuity insulation and loop tests, the the RCD test is purely that, an RCD test.

Anyone got any ammo I can use to shoot down his argument? Or am I in fact wrong on this occasion?

 

[Guest123]

Hello,

Please can you help settle an argument I've got going on at work at the mo. It is about testing RCD's.

I say you can test RCDs/RCBOs at the device itself. I just place my leads on the load side of the device and perform the test.

My colleague says you need to go to the end of line to perform the test. His reason for this is, "you are then testing through the whole of the circuit". I've no idea what he's going on about but he is adamant.

As far as I can see, the whole of the circuit has already been tested with your continuity insulation and loop tests, the the RCD test is purely that, an RCD test.

Anyone got any ammo I can use to shoot down his argument? Or am I in fact wrong on this occasion?

You are 100% correct.

It states it in GN3.

 

[chris gray]

wheres the eol on a ring?

 

[Sintra]

Yes an RCD should be tested at the device with the load disconnected.

 

[Jason Smith]

your right. Be prepared for when he throws the EWa regs at you- must not work live unless its ...etc etc. Testing at a socket with a plug in prevents having to go anywhere near live parts.Mite be where he is coming from mate, but when he sees he is loosing the argument be ready for him !! Ha ha hope its all good natured stuff.

 

[Johno]

i think he's winding you up so you have to walk further

 

[tigerpaul]

Thanks chaps,

I knew i was right, but you know when someone is so adamant that they are right and you are wrong, and then you start to question yourself?

cheers!

And yeah, E.O.L on a ring didn't make sense at all.

 

[DurhamSparky]

i just pick a socket/cooker socket or the easy light fitting to take readings and test!! handy combining a ZS and RCD on same fitting at end of line on lights!!! just a pain if you dont have some body to reset RCd/bo for you!

but if the rcd does 3 items i get one reading

 

[Sintra]

The reason an RCD should be tested at origin with load disconnected is if you are testing on energised circuit with appliances etc on load there will more than likely be some earth leagage on the circuit or circuits.

So for example there might already be 10mA of leagage to the RCD.

Then you test at half current of 15mA which added to the 10mA means you have 25mA of leagage.

If the RCD ramps at say 23mA then your half current test will trip RCD.

 

[acat]

When I did my assessment one of the tests I had to do was just that an RCD at source so yes I think we are all agreed your adamant mate has got it all wrong take a camera and post a pic of his face when you shoot him down in flames


Chris

 

[Spudnik]

Always do mine at the CU.

 

[tigerpaul]

The reason an RCD should be tested at origin with load disconnected is if you are testing on energised circuit with appliances etc on load there will more than likely be some earth leagage on the circuit or circuits.

So for example there might already be 10mA of leagage to the RCD.

Then you test at half current of 15mA which added to the 10mA means you have 25mA of leagage.

If the RCD ramps at say 23mA then your half current test will trip RCD.

Thanks everyone, but especially for this info, as I can really rubbish his argument now!

I wont see him until monday now, hopefully we'll have some more testing to do!

Cheers....