skts x 2 earth terminals

[driverman]

Been 2nd fixing today, which i've not done for many years. I've noticed that both Volex 13A twin & single sockets have 2 x earth terminals. Is that now standard? I thought that requirement was only applied to sockets that served a lot of IT equipment. Even years ago i would sleeve the earths separately, but then into one terminal. Is there any electrical reason for the change? Thanks

 

[Doomed]

Been 2nd fixing today, which i've not done for many years. I've noticed that both Volex 13A twin & single sockets have 2 x earth terminals. Is that now standard? I thought that requirement was only applied to sockets that served a lot of IT equipment. Even years ago i would sleeve the earths separately, but then into one terminal. Is there any electrical reason for the change? Thanks

Just so the socket can be used for any situation.
Just get into the habit of using both terminals when doing a ring main, it only takes a few seconds more.

 

[Tidy Max]

Why should you use both terminals when doing a ring main?

 

[ayjay]

same q as t/max?

 

[driverman]

Just so the socket can be used for any situation.
Just get into the habit of using both terminals when doing a ring main, it only takes a few seconds more.

Ohh i've no problem with it at all. I've used them both today. Even bent each wire earth wire back 3 times to ensure good connection/strength. Just wondered why they are being introduced

 

[Deleted member 26818]

There's no reason to use both terminals, unless there are 2 separate CPCs.

 

[Tidy Max]

If you used both terminals for the ring main the earth within the socket would be completing the cpc continuity. I always put both cpcs in one terminal and the other terminal for the back box bonding.

 

[driverman]

There's no reason to use both terminals, unless there are 2 separate CPCs.

As you know, 2 x CPC's in a ring final circuit

 

[driverman]

If you used both terminals for the ring main the earth within the socket would be completing the cpc continuity. I always put both cpcs in one terminal and the other terminal for the back box bonding.

Right, understand. so no requirement as such then to use both separately on a ring. I suppose if both used could make fault finding bit easier as you could disconnect 1 x earth as opposed to untwisting/ separating the 2 cpc's

 

[Tidy Max]

There is only one CPC in a ring final? You would use two protective conductors in a circuit with high protective conductor current?

 

[Doomed]

Why should you use both terminals when doing a ring main?

I didn't say you should, its just a habit to get into that hardly takes any extra time.

 

[Tidy Max]

Right, understand. so no requirement as such then to use both separately on a ring. I suppose if both used could make fault finding bit easier as you could disconnect 1 x earth as opposed to untwisting/ separating the 2 cpc's

I never twist, i always sleeve them separately then put both in the same terminal. Tighten until it squeaks with pleasure then tug test

 

[Doomed]

ugh, twisted earths, the bane of fault finding / testing!

 

[Tidy Max]

I didn't say you should, its just a habit to get into that hardly takes any extra time.

But why get into the habit at all? I am not trying to be smart or funny with thee if it is coming across that way. I just don't understand the reasoning. Which is true for alot of the stuff i read on here and 99 times out of 100 i come away having learnt something so i thought that may be the case here!

 

[Doomed]

So when you do a IT related circuit (assuming you do commercial) you are already in the habit - one of my colleagues has been heard muttering to himself when on commercial installs because he has 'got into the rhythm' and then forgot to use both terminals.

 

[Deleted member 26818]

2 terminals and 1 CPC = twice as many terminations which may fail.

 

[Tidy Max]

Never done one mate! The bulk of my work is domestic and sub contract. Interesting to know What sort of earth leakage do you get on commercial IT circuits. I did some aesthetic lighting on a large health centre a couple of years ago and noticed they had run a 4mm earth to all of the sockets even though they had been wired in T+E

 

[Deleted member 26818]

So when you do a IT related circuit (assuming you do commercial) you are already in the habit - one of my colleagues has been heard muttering to himself when on commercial installs because he has 'got into the rhythm' and then forgot to use both terminals.

There does appear to be a misinterpretation of the requirements for 2 separate CPCs for such circuits.
One conductor run in a ring formation and terminated at separate terminals does not equate to two CPCs.
It needs two separate conductors, each connected to a separate terminal in order to comply.

 

[driverman]

ugh, twisted earths, the bane of fault finding / testing!

Exactly, never have liked twisting conductors together. As an apprentice years ago, it was the norm to twist (was imperial then) conductors together. When metric cables came out, many electricians still twisted conductors together. In my opinion very bad practice. I doubt if many twist conductors together nowdays! Or do they ?

 

[Doomed]

Never done one mate! The bulk of my work is domestic and sub contract. Interesting to know What sort of earth leakage do you get on commercial IT circuits. I did some aesthetic lighting on a large health centre a couple of years ago and noticed they had run a 4mm earth to all of the sockets even though they had been wired in T+E

The circuits have never been 'loaded up' while I have been on site, someone else plugs the computers in (normally). If we are not working to a designers drawing we base our installs on what we have known designers to do, limiting the number of machines on each circuit etc, and once again we don't get involved in plugging the machines in (normally). We have never been called back because of a problem, so the designers / our copying must be working OK.

 

[Deleted member 26818]

There are arguments for both.
Twisting together would allow for continuity of the conductors, if the terminal became loose.
Twisting together restricts the number of conductors that can be terminated.
Twisting together is a pain when it comes to testing.

 

[Tidy Max]

The only conductor twisting i do is when i am installing or building an induction loop!

 

[Guest77]

I cannot see the problem myself, if you connect the CPCs into seperate terminals and one breaks or isn't tight the socket is still protected, if in one terminal then the same as it always has been, who cares, it is no big deal either way on a standard domestic outlet.

 

[Guest77]

Why should you use both terminals when doing a ring main?

Why Not?

 

[Deleted member 26818]

Some sockets have 2 terminals for each of the circuit conductors.
This increases installation times and increases the likelihood of a termination loosening.
If one terminal fails, then yes the conductor is still connected, though using a plug in tester would not show that a conductor had fallen out.

 

[driverman]

I cannot see the problem myself, if you connect the CPCs into seperate terminals and one breaks or isn't tight the socket is still protected, if in one terminal then the same as it always has been, who cares, it is no big deal either way on a standard domestic outlet.

i can't see it making any difference what so ever. However, as not in the game as such I just wondered why the introduction. Surly must be more expensive to produce, therefore there must be a reason why. Could it be an EU instruction?

 

[Risteard]

Presumably it is to enable the socket outlet to be used where there are high protective conductors currents.

Personally I would always use both terminations.

 

[Deleted member 9648]

i can't see it making any difference what so ever. However, as not in the game as such I just wondered why the introduction. Surly must be more expensive to produce, therefore there must be a reason why. Could it be an EU instruction?

EU are not interested in UK sockets....the reason is manufacturers dont have to manufacture both types....cheaper to tool for one only,and the extra cost of the two terminals is sneaked onto us.

 

[SJD]

In fault-finding an RFC with a higher-than-expected value for r2, on at least a couple of occasions it has turned out to be due to relying on the socket internal metalwork.

One end of the RFC into one terminal, the other end of the RFC into the other terminal. Screws done up tight. But the sockets had riveted bits of metal work, not always making good contact. I've seen sockets with the best part of an Ohm measured between the two terminals.

 

[Tidy Max]

I had the exact same issue about 6 months ago. It was a single socket that had been connected up that way causing the issue. I re terminated them and the lowered the value however after reading this thread i was thinking the terminations just may have been a bit crap!