BS 7671 doesn't (currently) require OPDDs (open-PEN disconnection devices) to be "tested" after installation - manufacturers may have functional test recommendations on installation and for regular maintenance.

Similarly, BS 7671 doesn't require RDC-DDs to be tested - again, manufacturers may have functional test recommendations on installation and for regular maintenance.

It is an interesting question - as you note the devices have not been around very long, and the designs and the associated regulations are still fairly immature, so for the time being there is no requirement to test and probably will not be for a while. In part we do not know what the likely failure mode is, nor the likely failure rate - no need to mandate a test for something that never happens, so we need to wait a few years until we have real in the field failure data.

However, it is interesting to think how such a thing may be tested. Given the propriety  detection methods it seems that the best thing to do would be to try it on a supply with a wandering neutral earth offset. The nearest emulation of a real fault would be to interrupt the neutral to the device, and insert a series transformer winding of several tens of volts and high current, or maybe to fake this with some sort of inverter / high power audio amplifier type design. A controlled voltage may then be added to or subtracted from the supply neutral to create a deliberately off-centre neutral to exercise the protection.  A simple transformer could only add or subtract to create a neutral above or below target, but in phase with the chosen phase of the supply. The inverter method has the advantage that the neutral to fake neutral offset voltage could have any arbitrary, even time varying, phase.

Mike

It would depend on whether it's a stand-alone device,or built into the charging equipment. Probably best left to the manufacturer to make a recommendation.

After all, we don't test ALL protective devices in BS 7671 ... we only ever test RCDs, and even there it's been made clear we don't test all their functionality either, only a press of the test button, and test the AC-type operation at I_Δn. AFDDs can be tested if there's a test button - I guess if a test facility is provided by the manufacturer of an OPDD, then pushing that and seeing it works would be the recommendation (again, though, not required if the OPDD is "self-test" built into a charging point).

Not sure would always I agree on relying on the makers - they do have a certain interest in selling more!

But the point that we do not test everything is more or less what I was trying to say- RCDs are internally complex and have a poor reliability  record, and so tests are mandated - and indeed tests do find faulty ones, suggesting the approach is sensible.

Fuses and MCBs do not have the poor track record, so testing is not mandated by standard. Of course there is nothing to stop people testing beyond the BS minimum - and the slew of RCD tests one can do, and may well do, as part of diagnostics in a defective system are a case in point, and circuit breakers certainly are tested in critical situations, but in most cases the failure risk is acceptable.

PEN break detection may never have a mandated test regime, if it proves not to really  need one, but there will still be a need to verify function in cases of doubt or peculiar behaviour.

Mike

Agreed, fault-finding etc. it might be necessary to check operation of more complex protective devices ... although even with RCDs the in-built test device doesn't always help.

I notice you didn't mention AFDDs ... these are complex, and would require a complex simulator to identify the condition (it may well be swap-out for another one is an early option in the fault-finding algorithm depending on cost of test equipment).

With OPDDs, you'd need to know which method of operation the device is using, and similarly inject appropriate voltages (and in some cases, currents as well) one way or another, without damaging associated equipment, which is a major consideration for devices built into charging points.

Is it me or is testing a Surge Protection Device like testing a cartridge fuse?

I know there are testers which have SPD tests as one of their functions, which appear to be a ramp insulation test, steadily increasing the insulation test current until the SPD operates and displaying the result.

How many times could this test be carried out before the SPD fails permanently?

I cannot ever imagine the IET recommending carrying out potentially destructive testing, which is what SPD testing appears to be to me, which makes some functions on new testers unnecessary?

Sparkingchip said:

Is it me or is testing a Surge Protection Device like testing a cartridge fuse?

Sort of - they will only be rated for a certain number of guaranteed "events" at different voltage levels.

Sparkingchip said:

I cannot ever imagine the IET recommending carrying out potentially destructive testing, which is what SPD testing appears to be to me, which makes some functions on new testers unnecessary?

It's one of the reasons most industry practice now recommends limiting the number of tripping-tests of RCDs to 2 (i.e. 0.5x, no trip and 1x, 0 and 180 degrees) when carrying out initial and periodic verification according to BS 7671. RCDs only have a certain number of anticipated operations.

mapj1 said:

Not sure would always I agree on relying on the makers - they do have a certain interest in selling more!

Interesting perspective ... it was manufacturers who were leading voices when it was determined (shortly after the commencement of Electricity at Work Regulations and introduction of portable appliance testing) that production-line or type-test 'flash tests' were appropriate to carry out on a regular basis, resulting in damage to and destruction of a large number of electrical products, some brand new.

I remember a local construction equipment hire company building a booth for Portable Appliance Testing with thick rubber matting on the floor and an observation window so other staff could see if the person testing had been electrocuted, because they were Flash Testing electrical equipment prior to every every hire period, which meant some equipment was being tested many times a year, sometimes more than once a week for equipment that was being hired for a day or less.

gkenyon said:

Sparkingchip said:

Is it me or is testing a Surge Protection Device like testing a cartridge fuse?

Sort of - they will only be rated for a certain number of guaranteed "events" at different voltage levels.

Which connects with my question, how do I know that my SPD is still working? I think the answer here is that the green flag is still showing. Do we trust it or not?