OK...

[333rocky333]

The schneider acti9 / resi 9 RCBO ranges now come with a leaflet which amongst other things says..



Will at least it says 'can' in this instance...rather than will...

I noticed that too, i had to read the instructions as I could not find the test button

 

[EFLImpudence]

Perhaps the link through from Adams post through to the suggestion I gave above is a little vague, but I still don't know where I said that MCBs should have their load disconnected before switching MCBs, as you did.

I was just extending your thought that loads should be disconnected before switching off the RCD with the test button.
Neither requires that.

You suggested something might be implied in their flawed instructions. It wasn't.

 

[333rocky333]

Can someone please explain the difference between using the test button to switch off and using the test button to test.

your well aware how the test function works
I would quess pushing the dolly off is a lot better for the devise than constantly using the test button, which after all is the test button, not that theres any reason to turn it off that often anyway.

I also note test monthly, thats only the case for hazourdous areas, isnt it, they seem to me concerned about overzealous use of the test facility, arc flashing and explosions

 

[ericmark]

In a MCB there is a arc arrested built in, not sure if these are fitted to RCD's? The RCD is emergency switching and very likely not with high loads, where the MCB will trip with high loads so yes see how the test should not be done when under load.

As to the adaptor to allow a British plug to be fitted into a French outlet, the problem is the German outlet is very similar, but the earth is a side bar rather than the pin and also there are loads where there is no earth connection at the socket.

I note the German system had RCD protection well before us, likely to try to compensate for the poor design. Some of the adaptors place the earth pin of the British plug where it will contact the side pin of the German socket, and the whole of EU seems to have a collection of similar sockets to each other but not exactly the same. This is also the case for Turkey, and Tunisia where they seem to have nearly all German sockets but with a few odd exceptions.

Unless the adaptor came with a socket tester you can never be 100% sure it is OK. I know many caravan people have testers to check polarity and earth because it is so common to have faulty installations at the camp site.

 

[EFLImpudence]

your well aware how the test function works

Indeed, but I am prone to sarcasm.

I would quess pushing the dolly off is a lot better for the devise than constantly using the test button,which after all is the test button,

What about RCD FCUs that don't have a switch?

not that theres any reason to turn it off that often anyway.

That's true, so would it not be sensible to take that opportunity to use the test the button?

I also note test monthly, thats only the case for hazourdous areas, isnt it,

Not sure.

they seem to me concerned about overzealous use of the test facility, arc flashing and explosions

They do not say why their devices are dangerous.

 

[John D v2.0]

I had a look at the spec of RCD the one we have
If it's rated 63A it should be able to break that.
If it's overloaded when you test it, maybe it won't work correctly. But I can't imagine most people test it while the shower is on, the immersion is on, they're cooking, etc.

 

[JohnW2]

I would quess pushing the dolly off is a lot better for the devise than constantly using the test button, which after all is the test button ...

Why do you guess that? What surely matters to the device is that the contacts open (whilst carrying whatever current) - as far as I can see, those contacts do not know or care whether they are being opened because of the trip mechanism or the manual operation of the lever, do they? Indeed, it's not difficult to argue that use of the test button is actually more desirable, since it 'exercises' the trip mechanism, hence makes it more likely that it will work as expected/required if it ever has to (should do).

.... they seem to me concerned about overzealous use of the test facility, arc flashing and explosions

What exactly do you mean by "overzealous"? Schneider certainly do not appear to say what they are concerned about.

I would think/hope we could all agree that whatever Schneider are trying to say, they have worded their instructions extremely badly.

Kind Regards, John

 

[333rocky333]

Remind me again how the Test buttons wired, I was thinking if the test button tries to break 32 amp where would that current try to go even for a fraction of a second once the switch starts to go off and the buttons held in.

 

[EFLImpudence]

The test button on RCDs just connects load side L to supply side N, via a resistor, on either side of the coil causing the imbalance.
Some (all?) RCD FCUs actually connect E.

I do not know the value of the resistor (John probably does) but I would be surprised if it was exactly matched to allow the 30mA.

 

[JohnW2]

Remind me again how the Test buttons wired, I was thinking if the test button tries to break 32 amp where would that current try to go even for a fraction of a second once the switch starts to go off and the buttons held in.

It's no different from any other switching situation - whether in a switch, a relay/contactor, an MCB/RCD/RCBO or whatever. When the contacts start to separate, the current "tries to go" across the gap (i.e. arcing), but (with AC), that is very short-lived.

"Holding the test button in" makes no difference. Once the trip mechanism is triggered, the trip mechanism is triggered, and once the contacts open, the current through the 'test resistor' also ceases (which stops the resistor getting fried, even if people lean on the test button for ages). Of course, if the RCD is faulty and does not operate in response to the test button being pressed, then the resistor might fry if one keeps the button depressed.

Kind Regards, John

 

[333rocky333]

not having much electronics background, surely its not a good idea shorting a resister across L and N, normally it would be subject to 3 maybe 12 tests, though with sockets they do recomend each use, so would be a lot more.
I quess as its only for milliseconds its not so bad

 

[JohnW2]

not having much electronics background, surely its not a good idea shorting a resister across L and N,...

That obviously depends upon the value of the resistor. If it had a high enough resistance such that current/power would be very low, it would not really be a 'bad idea'.

If I recall correctly, the test button resistors are usually roughly in the range 4k - 5k (hence producing a 'test current' of some 45-60 mA at 230V). That corresponds (at 230V) to a range of power (dissipated in the resistor) of around 11W - 14W. That is, indeed, an awful lot for what is probably a 0.5W rated resistor at best - but, as you go on to say, it's only usually for a couple of dozen milliseconds. As I said, the only problem arises if the RCD fails to trip, but the person keeps the button pressed - in that situation the resistor would probably burn up fairly quickly.

If the RCD does trip as expected, no harm will come to the resistor and it will fairly rapidly cool to ambient temp, so it wouldn't really matter if one pressed the button several times every day.

Kind Regards, John

 

[Spark123]

As it is only for milliseconds the power dissipated by the resistor (old wylex RCDs are somewhere in the region of 1.8KΩ) is very low, it shouldn't get chance to warm up. It is only when it the RCD fails that the resistor gets toasty and bad things happen.

 

[Echo the husky]

Some things certainly do seem to get lost in translation, found this tag on a fridge today. I get it, but I can't imagine the average user will have a clue what it means.