Testing an ‘A’ Type RCBO 10 Times and NOT the Standard 5 Tests to Prove the Effectiveness of the RCD

In this video we show how to test an ‘A’ type RCD but not 5 times as standard practice but 10 times. We show how to test this ‘A’ type RCBO with our Megger MFT set on the AC setting and then test it 5 times. Next on the Megger MFT we select the ‘A’ setting RCD function and test the RCBO again a further 5 times.

We would carry this test out 10 times on any ‘A’ type RCD and NOT just because it is a Wylex one with our learners at Tresham College.

Socket outlets rated up to and including 32 amp under the 18th Edition Wiring Regulations BS 7671 require additional protection by an RCD rated at 30mA or less.

Also under the 18th Edition Wiring Regulations BS 7671 all RCD’s require functional testing at a maximum of every 6 months intervals.

Videos are training aids for City and Guilds (C and G) and EAL courses Level 1, 2, 3 plus AM2, AM2S and AM2E.

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[GSHElectrical]

UPDATE guidance

BS 7671 Testing RCD’s - Regardless of the Type of RCD Test it as if it is an AC RCD at x1 ONLY

[dsesuk]

Good vid chaps. I hadn't thought about it, but I guess a tester set to Type-A performs the test with a DC component injected, so it makes sense to repeat the tests on the AC setting to ensure it behaves as expected. I use Easycert which dropped the 1x test column when 18th came in and put that flimmin' AFDD checkbox in there. I believe Easycert is designed to be compatible with NICEIC's paperwork to allow direct printing from the app, so that suggests NIC no longer have the 1x column. I print my own custom certs, so I haven't seen a blank NIC one to be sure. If they were going to drop a column, I'd rather it was 'number of points served' which isn't on the model forms and I always leave blank as BS7671 doesn't define what a 'point' is, so one installer's count may differ from another's!

[dannymort]

Thanks for the video. I was under the impression if the RCD was used for additional protection you record the highest at 150 mA and if it was to be used for fault protection record the highest value at 30mA.

[mgmorganelectricalsolution]

Can i ask why the 1/2 setting was only tested on 0 degrees? Not a criticism just wondering. Also, surely the function button should be classed as a test? So should it not be 13 in total?

[PJB]

Hi, great video again 👍🏼. Personally I would record the highest of the x5 150ma. As 30ma RCD’s are for additional protection. I also still cannot believe that electricians are still installing AC type RCD’s. British Gas are still installing AC RCD’s Chint boards in my area. Knowing what I know now, it’s madness. Keep up the good work guys in educating & helping sparks

[mikeenglish]

Another interesting and informative video 👍

[NBundyElectrical]

Any one had a problem, testing Hager RCD’s? Tested 6 recently all new type A and readings coming out at 136ish mA? Cheers guys great videos

[asamitchell]

If it's a brand new installation a ramp test should always be performed to verify you dont have an overly sensitive device so eleven test for a new installation.

[seandempsey]

You should have tested on the 1/2 times at 0d and 180d as for the 1 times and 5 times test

[brad]

Hi, Great video again. It's my understanding that you recorded the 5x operating time in the single column on the 18th Edition model forms, is this incorrect? If so does it state this in the regs? Thanks in advance.

[jayja]

Those Wylex metal blanks, do they get a good enough earth connection from the case? I would have thought that the lacquer / paint might prevent a good connection, and then there’s an unearthed conductive part of the consumer unit exposed.

[lansdorf]

Is it acceptable to test the device without the circuit connected to it.

[richardwash]

Nice one lads, good piece of information. 👍

[ishkebab]

Niceic certificates/reports do not have the 2 columns for rcd measurements, only 1 in line with the model forms of bs7671.
No controversy here 👀👀

[sandeepshetty]

Can you please do ramp test also. 🙏 ther is two reading coming on test which one we need to record? Higher or lower value 🤔
Thnx

[robertslapsevskis]

Really like your videos, I think they are great. But why are you testing type AC RCD when you have a type A RCD? There is no need for it. It is not that type A trips for a different reason compared to type AC RCD. The reason why type A RCD is sometimes selected is that it will still trip if there is a presence of pulsating DC up to 6mA. Type A RCD won't trip on DC, but it will trip on fault conditions on AC circuit if DC is present. DC can stop Type AC RCD working properly in fault conditions. That is why they are selected for car chargers, washing machines computers etc. For example electric car chargers (EVSE) can't be installed with Type AC RCD because the car could leak DC but can be instslled with type A RCD if the unit can detect DC current over 6mA and disconnect supply if that happens. Otherwise type B RCD would be required. Just for the interest - how many times would you test type F RCD? And Type B RCD?

[MaxEpsom]

In 1st test we putting 15ma should not trip and when passing fault of 30ma should rcd trip and you mentioned maximum time of operation 300 where can I get this is it written on rcd or on side guide
Thanks

[dunckeroo]

Class A GFCI breakers and receptacles in North America trigger at 5 mA +/- 1 mA in 25 ms. Class C (for over 300 volts) trigger between 15 and 20 mA. In Britian 10 mA trigger RDC receptacles are available, but 30mA is more common.

[seandempsey]

Correct me if I’m wrong but that RCBO is labelled as type B 32 or all RCDs / RCBOs or are they all labelled that way ie B6 B 32 and so on irrespective of the type? I always thought B32 or what ever means it’s a type B ?

[BG]

Can you test a B Type RCD, for EVSE charger? There are some cheap chinese options ~90 usd and I'm curious if it works.