Why does the UK use rings for sockets?

[pc1966]

I'v obviously lead a sheltered life, especially over the last four weeks, cost seem a bit prohibitive, but then if you take into account the three modules it replaces, perhaps not that expensive, thanks for that.

With AFDD you are looking at something in the £1-2k region for a full CU at trade price, so it is something that is a very difficult to sell to most folk.

It is also a little unclear as to how effective they are in real terms, and so far no test equipment that I know of so for the 'AFDD' aspect you are trusting the self-test, though obviously you can verify the RCD action which provides some confidence on the electronics and mechanical trip reaction.

I suspect they will come down in price though but no idea how long for that to show.
[automerge]1587811846[/automerge]

I have come to the conclusion that you can't get true separation of 3mm on each pole without the extra width, which seems logical when you consider the doubling up of the number of mechanical components needed, obviously flying leads are not required.

I can't see a problem in getting 3mm clearance when open, but I can see a problem in having an arc-quench chamber in a single-module size device if you were interrupting a N-E fault at high current.

Do you have a specific reason for needing this?

 

[Mike Johnson]

I think you'r right, the problem is IMO, domestic electrical instals are to a greater extent very reliable, so it's not seen as a priority to improve what is already working well, the old adage "If it ain't broke......." seems to be the majorities mantra.
[automerge]1587812322[/automerge]
@pc1966 the only reason for needing this is the French regulations which stipulate dual pole 3mm gap, they are a bit behind in not using RCBO's in the main, but the availability of true dual pole units is getting better, I wont go into what I think they do better as it will start a very long debate. I am still looking for the "sat on the fence" smily.

 

[Mike Johnson]

As close as I can find, but looks painful.

 

[pc1966]

If you really need dual-pole tripping because you might have a L-N polarity reversal, etc, then it would need to be really a 2-P breaker (i.e. thermal/magnetic trips on both poles).

Is that a real concern? I guess you always have a high capacity dual-pole RCD incomer anyway due to them all being TT supplies?

 

[Mike Johnson]

The single module units offered in the UK do not have the thermal/magnetic trips on both poles, hence they do not comply with the French Regulations.

The incoming RCD is in reality set up to stop the consumer exceeding the tariff they are paying, there used to be a bit of head room to this, but with the installation of smart meters this head room has been drastically reduced, from what I have been told from 10% to 2%, most consumers who where on the limit prior to the change over have to upgrade their tariff at a cost.

 

[Mike Johnson]

@telectrix

View: https://youtu.be/TUsbRGVVLP0
apologies if you can’t stand Nagy

Interesting to watch Nagy at 2:18 and how much pressure he is putting on his torque screwdriver to get it to click over, seems to fly in the face of those that told me that 2.1N is only just over hand tight.

 

[pc1966]

Interesting to watch Nagy at 2:18 and how much pressure he is putting on his torque screwdriver to get it to click over, seems to fly in the face of those that told me that 2.1N is only just over hand tight.

He may be putting more downwards pressure to stop it camming out the screw head.

I have found that 4Nm is about as much as I can sensibly do single-handed, but that is not while worrying about a pozi screw head (e.g. when using a hex socket, etc).

 

[Ian1981]

Interesting to watch Nagy at 2:18 and how much pressure he is putting on his torque screwdriver to get it to click over, seems to fly in the face of those that told me that 2.1N is only just over hand tight.

I’ve got the same torque screwdriver, you do have to apply a bit of pressure on the 2.8Nm for the Hager mcb,s , Schneider rcbos are from memory around 2Nm so not so much pressure

 

[Mike Johnson]

Of course he is trying not to cam out the screw head, what I was alluding too is the comment made on a different thread that 2.1N is only just over hand tight, you would not need both hands for that, it was a very miss-leading comment when I was trying to find out how difficult turning a torque screwdriver was, I will try to find the thread and post on here, I eventually set up a rig to test my Armeg and found it was way over calibrated and sent it back.

 

[pc1966]

Trying to decribe force is very difficult to do as you need some sort of reference that people have in common, and screwdriver use varies a lot even among engineers. I find 2.1Nm is not that hard to do single-handed, will try to film something later but never posted a video so far so it might take a bit of faffing about.