Double Socket Addition in Attic

[tododo]

Hi all

I already have a professionally installed double socket in the attic - done when the house was re-did about 9 years ago

That double socket has its own "switch" on the consumer unit (rcd i think its called)

Anyway all I want to do is put another doube socket closer to the hatch

Ive bought some 2.5mm t&e cable and just connected up into the existing socket and placed the double socket where I want

Just wanted to see if this is OK - I see this as basically an extension lead as that what was previously plugged into the original socket anyway

Thanks for any advice all!

 

[deadshort]

Hi, if the socket has it's own MCB rated at 16a or 20a you can add your socket as you intend to do using 2.5mm.

Kind regards,

DS

 

[EFLImpudence]

Hi, if the socket has it's own MCB rated at 16a or 20a you can add your socket as you intend to do using 2.5mm.DS

Most people seem to forget that 25A is also acceptable for 2.5mm² cable.

However, as the new length of cable will be protected by the two 13A fuses in the plugs, the circuit OPD is not relevant (within reason) - as long as the existing circuit has been installed correctly.

 

[JohnW2]

Most people seem to forget that 25A is also acceptable for 2.5mm² cable.

True, but (a) 25A MCBs are not necessarily easy to find (or necessarily available for a particular CU and (b) as you know, your statement is only true for the most 'accommodating' of cable installation routes.

However, as the new length of cable will be protected by the two 13A fuses in the plugs, the circuit OPD is not relevant (within reason) - as long as the existing circuit has been installed correctly.

That's true in terms of the cable from first to second double socket. However, it would not be true of the cable from CU to the first socket (whose downstream protection would potentially consist of four 13A fuses).

Kind Regards, John

 

[EFLImpudence]

True,

Q.E.D.

but (a) 25A MCBs are not necessarily easy to find (or necessarily available for a particular CU and (b) as you know, your statement is only true for the most 'accommodating' of cable installation routes.

Not relevant in the context of the advice given.

That's true in terms of the cable from first to second double socket. However, it would not be true of the cable from CU to the first socket (whose downstream protection would potentially consist of four 13A fuses).

Are you suggesting someone might have fitted 2.5mm² cable with, for example, a 50A OPD and relied on the first socket being protected by its two 13A fuses?

I suppose anything is possible but I did say "(within reason) - as long as the existing circuit has been installed correctly".

So, with the information available, would you advise that the additional socket should not be added?

 

[JohnW2]

Not relevant in the context of the advice given.

I'm not so sure about that. The OP could easily have taken you comment to mean that 25A MCB would be an available option for him, and would, if available, be acceptable (without any caveat about cable installation method).

Are you suggesting someone might have fitted 2.5mm² cable with, for example, a 50A OPD and relied on the first socket being protected by its two 13A fuses?

No, but you appeared to be talking about the acceptability of the OPD's rating exceeding the CCC of the cable ('within reason') provided that the downstream OPDs (fuses) were (in total) rates at below the CCC of the relevant cable(s). I doubt that you (and certainly not me) were thinking of a 50A OPD (even though the argument would still hold even if it were 100A, provided that fault protection requirements were satisfied), but you may well have been thinking of 32A.

So, with the information available, would you advise that the additional socket should not be added?

I don't have enough information to answer that - since, as far as I am aware, we know neither the size of the cable from CU to the existing double socket nor the rating of the circuit's OPD. The present circuit could be said to be 'correctly installed' with 2.5mm² cable (Method C) feeding just one double socket, regardless of the rating of the circuit's OPD ('within reason' - i.e. provided only that fault protection requirements were satisfied). So, adding the second double socket (increasing worst-case downstream fuse protection to 4 x 13A = 52A) would only be acceptable/compliant if the circuit's OPD was not rated higher than the CCC of the cable from CU to existing socket - i.e. if it's 2.5mm² cable, then a maximum OPD rating of 25A if the cable is Method C, otherwise 20A.

Of course, if the existing socket is wired in 4mm² cable (again, we just don't know), then it would be OK.

So, in answer to your question, if I had the necessary additional information, I would advise that the second socket could be added if the first one is fed with 4mm² cable or, if it is 2.5mm², if the OPD is rated per above figures (max 25A if Method C, otherwise max 20A) - otherwise I would advise that the additional socket should not be added. Do you disagree?

Kind Regards, John

 

[ban-all-sheds]

Are you suggesting someone might have fitted 2.5mm² cable with, for example, a 50A OPD and relied on the first socket being protected by its two 13A fuses?

I can't speak for John re what he is suggesting.

But I can speak for myself and say that someone might have fitted 2.5mm² cable with a 32A OPD and relied on the first socket providing cable overload protection via plug fuses.

 

[JohnW2]

I can't speak for John re what he is suggesting. ... But I can speak for myself and say that someone might have fitted 2.5mm² cable with a 32A OPD and relied on the first socket providing cable overload protection via plug fuses.

Indeed ... but if you look, you will see that I suggested that very possibility to EFLI 10 minutes before you did

Kind Regards, John

 

[EFLImpudence]

I'm not so sure about that. The OP could easily have taken you comment to mean that 25A MCB would be an available option for him, and would, if available, be acceptable (without any caveat about cable installation method).

Ok. Then maybe the first cable is 1mm² so the original advice re. 20A MCBs is equally suspect.

No, but you appeared to be talking about the acceptability of the OPD's rating exceeding the CCC of the cable ('within reason') provided that the downstream OPDs (fuses) were (in total) rates at below the CCC of the relevant cable(s). I doubt that you (and certainly not me) were thinking of a 50A OPD (even though the argument would still hold even if it were 100A, provided that fault protection requirements were satisfied), but you may well have been thinking of 32A.

Ok. I accept that.
I was thinking of "properly" installed as having the correct OPD for the cable.
Until you brought it up, I had not thought of these unlikely occurrences. Perhaps 'properly'was not the right word.

 

[JohnW2]

Ok. I accept that. I was thinking of "properly" installed as having the correct OPD for the cable. Until you brought it up, I had not thought of these unlikely occurrences. Perhaps 'properly'was not the right word.

Unless I completely misunderstood, you surely not only thought about it, but actually wrote about it - and that was the (essentially only) reason I commented. When you wrote ...

However, as the new length of cable will be protected by the two 13A fuses in the plugs, the circuit OPD is not relevant (within reason) - as long as the existing circuit has been installed correctly.

... I assumed that "not relevant" meant that you were saying that it did not matter (within reason) if the rating of the OPD was above the CCC of the cable, since the downstream fuses would give "26A protection" to the cable (hence OK for Method C 2.5mm² cable). Is that not what you meant?

Kind Regards, John

 

[EFLImpudence]

Yes, but I was only considering/thinking about/had in mind a properly/normally/usually installed arrangement of circuit - we had already been told it was a radial to just this single socket - i.e. 1.5mm²-16A/20A; 2.5mm²-16A/20A/25A or even 4mm²-16A/20A/25A/32A where the OPD would have no bearing on adding a second double socket on 2.5mm² cable.

I have already conceded that I could have worded it better.



I think that sums it up before you accuse me of arguing for the sake of it?

 

[JohnW2]

Yes, but I was only considering/thinking about/had in mind a properly/normally/usually installed arrangement of circuit - we had already been told it was a radial to just this single socket - i.e. 1.5mm²-16A/20A; 2.5mm²-16A/20A/25A or even 4mm²-16A/20A/25A/32A where the OPD would have no bearing on adding a second double socket on 2.5mm² cable.

Fair enough - as you probably now realise, that's not quite how I interpreted what you wrote.

Needless to say, I agree that if the original circuit (to the existing socket) has a cable CCC which is no less than the In of the OPD, then it's OK to add a second double socket with 2.5mm² cable (or, indeed, a single socket with 1.5mm² cable) regardless the In of that OPD.

I think that sums it up before you accuse me of arguing for the sake of it?

I don't think either of us has been arguing. As above, I was just a bit confused by (misunderstood) what you were saying.

Kind Regards, John

 

[roganty]

Hi all

I already have a professionally installed double socket in the attic - done when the house was re-did about 9 years ago

That double socket has its own "switch" on the consumer unit (rcd i think its called)

Anyway all I want to do is put another doube socket closer to the hatch

Ive bought some 2.5mm t&e cable and just connected up into the existing socket and placed the double socket where I want

Just wanted to see if this is OK - I see this as basically an extension lead as that what was previously plugged into the original socket anyway

Thanks for any advice all!

Hi, if the socket has it's own MCB rated at 16a or 20a you can add your socket as you intend to do using 2.5mm.

Kind regards,

DS

Most people seem to forget that 25A is also acceptable for 2.5mm² cable.

However, as the new length of cable will be protected by the two 13A fuses in the plugs, the circuit OPD is not relevant (within reason) - as long as the existing circuit has been installed correctly.

Has no one thought to ask how he is connecting the new socket to the old?

Is it by plugging the new socket in to the old?

Or wired directly into the socket?

 

[EFLImpudence]

Should be wired direct - 2.5mm² T&E has been bought.

 

[tododo]

Yep is wired directly into the old socket - its seems my simple thinking maybe wrong - I would have to google a lot of the abbreviations

Thanks though guys - should it be a fused spur socket then??? Id like a double socket but not sure if there is a fused double switched spur??