1.5mm SWA, Acceptable or bad practice ?

[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

 

[Smugley]

Hi there, after reading this discussion it seems to me that some people are happy to use a cable size with a capacity barely above the nominal value of the MCB. Personally the reason I would go for a larger SWA in this case is because a 16A MCB may not trip until well over 20A, maybe 22A, according to Appendix 3 of the BRB. This brings your tolerance down significantly, and if there is any place along the run which causes the cable to derate, ie fed through bunches, under insulation etc, then the capacity of the cable may drop below the MCB trip current, and then you may have a problem. It's all about perceived risk I guess.

 

[flukey]

here we go again

 

[pevvers]

I'm saying nuffin...

 

[flukey]

I'm saying nuffin...

lol

 

[TPES]

Sod it, 6mm from now on.. keep everyone happy. lol

 

[not clever]

Couldnt be bothered to trawl through all the posts so sorry if I'm going over whats already been said.

Do the calcs & if all complies then just use the 1.5mm, nothing wrong with 1.5mm used for sso's if it complies.

Just because the norm is 2.5 don't mean you have to use it after all what size conductors would you use for sso radial circuit if MI was the cable of the day & you are thinking of proffits in the job.

Dont be drawn into this is the norm & this is how we have to do it, thats why your taught how to calculate cable selections

 

[pevvers]

Hear hear!

 

[The Truth]

Couldnt be bothered to trawl through all the posts so sorry if I'm going over whats already been said.

Do the calcs & if all complies then just use the 1.5mm, nothing wrong with 1.5mm used for sso's if it complies.

Just because the norm is 2.5 don't mean you have to use it after all what size conductors would you use for sso radial circuit if MI was the cable of the day & you are thinking of proffits in the job.

Dont be drawn into this is the norm & this is how we have to do it, thats why your taught how to calculate cable selections

here here

thou shalt not rely on the on-site-guide!!!

 

[flukey]

Couldnt be bothered to trawl through all the posts so sorry if I'm going over whats already been said.

Do the calcs & if all complies then just use the 1.5mm, nothing wrong with 1.5mm used for sso's if it complies.

Just because the norm is 2.5 don't mean you have to use it after all what size conductors would you use for sso radial circuit if MI was the cable of the day & you are thinking of proffits in the job.

Dont be drawn into this is the norm & this is how we have to do it, thats why your taught how to calculate cable selections

now MI is a totally different ball game, op was for opinions and thats what he got

 

[Modernelectric]

stick it to em pevvers!!