RCD Testing x5 150mA (or higher for Hager RCCB)

So, are the new Hager Type A 30mA R.C.D.s really 30 mA sensitive or are they 250mA sensitive?


This is a bit confusing. 


Clarification anyone please?


Z.

I have just come across a Youtube video about this very subject. I wonder what the trip times will be after the R.C.D. has stood unused or untested for a year or two and has become a bit sticky in operation?


You may need a language interpreter for this video that has wooley sound and unclear speech in places.

https://www.youtube.com/watch?v=c0dPUf_aZ4E


643.8 "The verification of the effectiveness of the measures for additional protection is fulfilled by visual inspection and testing. Where R.C.D.s are required for additional protection, the effectiveness of automatic disconnection of supply by R.C.D.s shall be verified using suitable test equipment according to BS EN 61557-6 (see Reg. 643.1) to confirm that the relevant requirements of Chapter 41 are met."


"NOTE. Effectiveness is deemed to have been verified where an R.C.D. meeting the requirements of 415.1.1 disconnects within 40ms when tested at a current equal to or higher than five times its rated residual current."


"Or higher than" eh?





Z.

I have always assumed that pushing the test button on an RCD or RCBO injects a fault current of 30mA.  I am now wondering if that is so, and that it is actually 150mA


David

I'm doing a new installation labour only,  this afternoon I unpacked one of the new Hager CU that they have bought for me to install.


The is the first CU I will fit with SPD and it's factory fitted, not quite in the way I was expecting , I thought it needed a MCB upfront of it and I wasn't expecting to see it connected into the main switch as it is.


I have just read the guidance from Hager on testing the RCDs, I won't be testing them at 50 mA x 5 as my Megger RCDT320 doesn't have a 50 mA setting, I will have to try 500 mA X 0.5 and see what happens.


It will be a few weeks before I do any live testing as the suppliers meter has not been installed yet to power anything up.


Andy 

Have a look at this it may be of some help.
https://youtu.be/c0dPUf_aZ4E

There is a note in the BEAMA RCD guide


TABLE 4 – STANDARD VALUES OF BREAK TIME AND NON ACTUATING TIME

For RCCBs and RCBOs of the general type with I∆n≤ 0,030 A, and RCBOs of the general type incorporated in or intended only for association with plugs and socket-outlets, 0.25 A may be used as an alternative to 5I∆n


Does that mean Hager are wrong supplying these RCDs for anything other than plug and docket circuits?


Andy

I thought it needed a MCB upfront of it and I wasn't expecting to see it connected into the main switch as it is

Those sorts usually have a one-shot thermal fuse in them (that if broken, cause a red bar to appear the window). This allows it to be used without MCB as long as the upstream device is "good enough". For example the Wylex SPDs that come in their CUs don't need protection if the upsteam fuse is <= 125A.


As an aside - I'm surprised by the orientation of that Hager SPD - if it had been manufactured with L,N below and E above, all three connection leads could have been substantially shorter, and for transients, the inductance of the leads has a large effect on the voltage that is passed through. For example, a typical type 2 SPD might achieve down to 1.5Kv across its terminals, but add in 1m of L+E leads, and that might increase to 3kV at the other ends of the leads. So rather than 1.5K reaching equipment, 3kV reaches it. It looks like maybe 30cm of unnecessary cabling there, which might be letting through another 0.5Kv.

Having just tested 2 Wylex R.C.D.s, a WRS40/2 and a WRS80/2 they both read 3.3kOhms for the test circuit with the test button pressed.


Z.

So a test current of 70mA at 230v then ( R= 230V / 3.3k ohms)

as I said, neither 30mA nor  5 times it, just something to make it trip.

Presumably those are marginal for use at 110V as well as 230V, although at 30mA test current would be only just about OK.

Of course a good 30mA RCD fires at about 20-25mA so really it is fine.