1.5mm SWA, Acceptable or bad practice ?

[TPES]

I know it depends on its inststallation method but what is the max current carrying capacity of 1.5mm swa 3 core?

If im looking at the correct table 4D4A it says 18a clipped direct.

But then this manufactures spec says 32a. (page 3) http://www.alertelectrical.com/upload/pdf/329armoured.pdf


I want to know if its acceptable to run a radial to 2 x outdoor sockets using 1.5mm SWA on a 16a mcb

 

[Mac]

Radials should be run in 2.5mm and put on a 20A breaker.

 

[sparks1234]

Radials should be run in 2.5mm and put on a 20A breaker.

Why?, nothing to say you cant back a 1-5 cable up with a 16 amp, personally I would install a 2-5 (obviously dependant on length) but cant see why you could condemn the 1-5

 

[TPES]

Radials should be run in 2.5mm and put on a 20A breaker.

Thats a new one, I thought perfectly acceptable on 16a.. this is T&E

SWA has a larger current carrying cappacity thinking a 10m run in 1.5mm SWA would be ok..

According to this its 26A. 1.5mm 3 core Armoured Cable

Either way its well within the 16a MCB it would be on..

Is it bad practice and most of you would not consider this?

 

[Mac]

Why?, nothing to say you cant back a 1-5 cable up with a 16 amp, personally I would install a 2-5 (obviously dependant on length) but cant see why you could condemn the 1-5

Personally you would install a 2.5mm.I would definitely install a 2.5mm and put it on a 20A breaker.I'm not condemning the 1.5.Each to his own and my preference

Thats a new one, I thought perfectly acceptable on 16a.. this is T&E

SWA has a larger current carrying cappacity thinking a 10m run in 1.5mm SWA would be ok..

According to this its 26A. 1.5mm 3 core Armoured Cable

Either way its well within the 16a MCB it would be on..

Is it bad practice and most of you would not consider this?

I would still install 2.5mm.You don't know what they will plug into it at the end of the day.

 

[TPES]

dont dissagree with you, I would also install 2.5mm, its just that the customer has huge amount of 1.5mm and wondered if i could use it.

 

[Mac]

dont dissagree with you, I would also install 2.5mm, its just that the customer has huge amount of 1.5mm and wondered if i could use it.

Just run 2 lengths up then mate

 

[pevvers]

I would still install 2.5mm.You don't know what they will plug into it at the end of the day.

At the end of the day, if the cable is protected then the installation is safe, and a 1.5mm SWA will be okay on a 16A.

Thermosetting single phase SWA comes in at 27A with no corrections, so I'd say you would probably be okay with it even on a 20A, as long as you've done the corrections of course!

If im looking at the correct table 4D4A it says 18a clipped direct.

Are the sockets 3 phase then? As the single phase uncorrected CCC for thermoplastic is 21A in my book...

 

[Mac]

At the end of the day, if the cable is protected then the installation is safe, and a 1.5mm SWA will be okay on a 16A.

Thermosetting single phase SWA comes in at 27A with no corrections, so I'd say you would probably be okay with it even on a 20A, as long as you've done the corrections of course!



Are the sockets 3 phase then? As the single phase uncorrected CCC for thermoplastic is 21A in my book...

So your happy putting sockets on a 1.5mm cable

 

[pevvers]

So your happy putting sockets on a 1.5mm cable

Ummmm, am I protecting the cable from overcurrents?

Yes.

Whether it be lighting, sockets, FCU's, it matters not as long as the cable and all associated equipment is protected from overcurrents, will disconnect in the required time, etc., etc.

Just because it's 1.5 doesn't mean it can only be used for lighting, just like you could put in 16mm radial circuits for sockets if you really liked, although you would have a hell of a time getting them in the terminals!!

As long as the calculations add up then you are complying with BS7671, which is what I adhere to.

 

[scotsparky]

i would put sockets on a 1.5 and have done after i made the micc end off.

 

[andyb]

90 degree, 1.5 armoured clipped direct single phase, 27 amps.
Can anyone tell me why, providing all the other factors allow you would not protect this with a 20
amp mcb.

 

[pevvers]

90 degree, 1.5 armoured clipped direct single phase, 27 amps.
Can anyone tell me why, providing all the other factors allow you would not protect this with a 20
amp mcb.

Exactly. I don't know why people think that if it's a radial to a socket on 16A or 20A it needs to be 2.5 no matter what the cable type is. Someone's already brought up that it's okay for MICC, so why can't they see that it would be okay for SWA? Especially as the CCC of 1.5 MICC that are exposed to touch is less than that of 90 degree armoured!

But hey ho, some people are told that this is the way we do it, and they can't be budged even when common sense and proof from a British Standard document is in the mix.

 

[tigerpaul]

Agree fully with pevvers..

It may be the norm to have sockets on 2.5 and lighting on 1.5 but that isnt the be all and end all. As long as the cable is protected by the overcurrent device then thats it. (Dont forget Rating factors)

How many sockets are you feeding? And how many are likely to be in use at one time. One 13A socket is only going to draw up to 13A, if the cable is rated at 20 odd A and the overcurrent device is 16A, then I cant see a problem.

 

[Spudnik]

Personally i cant see a problem, however, i do see it as good practice to use 2.5 for socket outlets.

 

[andyb]

Personally i cant see a problem, however, i do see it as good practice to use 2.5 for socket outlets.

So is it better pratice to use 4mm and even better practice to use 6mm?

 

[Spudnik]

So is it better pratice to use 4mm and even better practice to use 6mm?

Depends what you are installing it for.

 

[flukey]

i can see what your saying and agree in principal but i still see it as good practice to use 2.5 radials

if however, the powers that be come up with a 1.5mm A4 radial circuit that features in 7671 then i would reconsider

 

[pevvers]

Well if you're referring to the nice pictures in appendix 15 at the back of the BRB, you'll see a nice note at the bottom saying that these cables sizes refer to BS6004 "flat twin & earth" cable...

 

[flukey]

Well if you're referring to the nice pictures in appendix 15 at the back of the BRB, you'll see a nice note at the bottom saying that these cables sizes refer to BS6004 "flat twin & earth" cable...

hi pevvers,
in answer to the op i would say that it is acceptable, but not good practice. my opinion only

 

[pevvers]

Well if that's the way you see it, then that's the way you see it!

What is the reason for it not being good practice then?

 

[xraytek]

I want to know if its acceptable to run a radial to 2 x outdoor sockets using 1.5mm SWA on a 16a mcb

As the designer of the circuit you need to establish the likely current demand (taking into account diversity). Then select the appropriate protective device, and choose a cable that is rated for that device.

If Zs and volt drop calculations are also within the requirements, and all meets BS7671 then I dont see what good or bad practice has to do with it.

It either complies with BS7671 or it doesnt.

 

[flukey]

theres the potential to run 26 amps through this double socket, what if he wants to add more at a later date

i know everything cant be future proof but i personally will keep to 2.5mm radials

stubborn old sod aint i

 

[pevvers]

Well what would be the point of putting it on a 20A breaker then?

Might as well just go for a 16mm and 63A MCB just so that he can add on another double socket and 1 single socket and then he can load them all up nearly fully with 65A!

 

[flukey]

now now pevvers, you know sarcasm is the lowest form of wit

these are after all personal opinions, you stick to yours and il stick to mine

 

[pevvers]

Oh I know that, but unfortunately that's the only form I possess...

But I think that the argument stands, if the original question is about a radial circuit, which with a 2.5mm twin would have overcurrent protection rated at 20A max, then if more wanted to be added then the overcurrent protection would have to be upgraded as well, along with the cable.

Of course, 2.5mm 90 degree armoured clipped direct could take more, but what crazy person would put a 2.5 on a 32A,

 

[flukey]

Oh I know that, but unfortunately that's the only form I possess...

But I think that the argument stands, if the original question is about a radial circuit, which with a 2.5mm twin would have overcurrent protection rated at 20A max, then if more wanted to be added then the overcurrent protection would have to be upgraded as well, along with the cable.

Of course, 2.5mm 90 degree armoured clipped direct could take more, but what crazy person would put a 2.5 on a 32A,

the original question was acceptable or bad practice, i answered acceptable but not good practice, there is a difference

also why would you upgrade overcurrent protection when adding another socket to a 20amp radial in 2.5

 

[pevvers]

Ahh, I admit defeat, but only because I've had a very long weekend and haven't got the brain power for all this at the moment, or the energy to read through it all again....

Until next time!

 

[flukey]

cant wait

 

[ICE]

Hi,
Personally I would use 2.5 backed by a B-type mcb of 20a

ICE

 

[pevvers]

So would I, but I would actually make it an RCBO instead of an MCB.

But a 1.5mm would be fine,

 

[flukey]

Hi,
Personally I would use 2.5 backed by a B-type mcb of 20a

ICE

hi ice,
dont start pevvers off again, weve only just agreed to disagree lol

 

[pevvers]

Heheh....

I've only just noticed that you'd editted a few of your posts, and I was contemplating starting again.

But there will be other times!

 

[TPES]

I'm with you on this one pevvers..

No one has yet given a valid reason and explained why they wouldnt use 1.5mm SWA on a 16a MCB, or even 20A MCB for that reason.

 

[flukey]

not edited, im just too quick with the return button so post goes on before ive finished

never had that problem with my trusty typewriter

i look forward to the other times, its good to talk

I'm with you on this one pevvers..

No one has yet given a valid reason and explained why they wouldnt use 1.5mm SWA on a 16a MCB, or even 20A MCB for that reason.

hi sid,
dont need to explain myself, because thats the way I do it. lets leave it there shall we

 

[ICE]

In all honesty, If I was running a Radial socket outlet in my own House it would be in 4mm and it would not be protected by a 30mA as they are a Pigging nuisance although if it was for anyone else it would be protected.

 

[flukey]

In all honesty, If I was running a Radial socket outlet in my own House it would be in 4mm and it would not be protected by a 30mA as they are a Pigging nuisance although if it was for anyone else it would be protected.

get your tin hat ready ice

 

[ICE]

Lmfao...............

 

[pevvers]

It would not be protected by a 30mA as they are a Pigging nuisance although if it was for anyone else it would be protected.

Even if it was for external use as was stated in the OP?

Fair do's if you wanna use 4mm though, whatever floats your boat I suppose, seems an extra expense for no apparent reason to me though.

 

[TPES]

In all honesty, If I was running a Radial socket outlet in my own House it would be in 4mm and it would not be protected by a 30mA as they are a Pigging nuisance although if it was for anyone else it would be protected.

4mm radial in SWA seems way over the top.
2.5mm is well within the regs and calcs limits.
If you wanted to i think1.5mm Seems perfectly acceptable, there would still be no overloading issues.

 

[pevvers]

I think it's just me and you Sid....

 

[TPES]

I think it's just me and you Sid....

Ha ha, Seems to be..

Who else wants to be in our "1.5mm SWA GANG" ?

 

[acvc]

Surely it all comes down to design current less than protective device rating less than current carrying capacity? If that's the case, then it's ok with the Big Red Book.

Count me in!

 

[pevvers]

Viva la revolución!

 

[tigerpaul]

dont dissagree with you, I would also install 2.5mm, its just that the customer has huge amount of 1.5mm and wondered if i could use it.

Use it! Save yourself some money!

As said earlier, if its protected then theres no problem....
If your really worried, make it a ring if theres no shortage of cable!

 

[pevvers]

Oooooh no, you couldn't do that. A 1.5mm ring? Who's ever heard of such a thing, that can't be good practice, there's no diagrams showing that anywhere...

I know, lowest form. But that's what it comes down to in the end, that's what you've been taught so you're set rigid in your ways.

 

[ian.settle1]

I know it depends on its inststallation method but what is the max current carrying capacity of 1.5mm swa 3 core?

If im looking at the correct table 4D4A it says 18a clipped direct.

But then this manufactures spec says 32a. (page 3) http://www.alertelectrical.com/upload/pdf/329armoured.pdf


I want to know if its acceptable to run a radial to 2 x outdoor sockets using 1.5mm SWA on a 16a mcb

Look at appendix 15 in the BRB

 

[andyb]

Appendix 15 relates to ''flat twin & earth''
In the note at the bottom of the page it touches on other conductor and cpc sizes.

 

[flukey]

I'm with you on this one pevvers..

No one has yet given a valid reason and explained why they wouldnt use 1.5mm SWA on a 16a MCB, or even 20A MCB for that reason.

looks like youve answered your own question then sid

also the cable you mention carries 21 amps in the brb before any cable calcs

 

[The Truth]

Ummmm, am I protecting the cable from overcurrents?

Yes.

Whether it be lighting, sockets, FCU's, it matters not as long as the cable and all associated equipment is protected from overcurrents, will disconnect in the required time, etc., etc.

Just because it's 1.5 doesn't mean it can only be used for lighting, just like you could put in 16mm radial circuits for sockets if you really liked, although you would have a hell of a time getting them in the terminals!!

As long as the calculations add up then you are complying with BS7671, which is what I adhere to.

well said