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!!

 

[pevvers]

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

No **** that is what he got!!

So how comes MI is a different ball game, but SWA with it's higher CCC is not? Surely the same rules apply?

1.5mm MI (bare and exposed to touch, as it would be in this situation) = CCC of 23A light duty and 25A heavy duty clipped direct and 25A light duty and 26A heavy duty on tray.

1.5mm SWA 70 deg c (thermoplastic)= 21A clipped direct and 22A on tray.

1.5mm SWA 90 deg c (thermosetting)= 27A clipped direct and 29A on tray.

Most of the time nowadays I find that SWA is thermosetting insulation, and so the 27A CCC would be the one to look at. Which is better than even the heavy duty MI by 2A... So, with respect, how is MI a different ball game?



P.S. I was being quiet Flukey, but you just wouldn't let it lie!

 

[andyb]

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

The op was not asking for opinions,

It was asking for the current carrying capacity of 1.5 3 core swa, this is in the brb so no opinion needed.

Also is it acceptable to run a radial in 1.5 swa to 2 x sockets on a 16 amp mcb, again verifiable in the brb so no opinion need.

What you are doing flukey is saying how you would do it, which was definatly not the op.

 

[flukey]

The op was not asking for opinions,

It was asking for the current carrying capacity of 1.5 3 core swa, this is in the brb so no opinion needed.

Also is it acceptable to run a radial in 1.5 swa to 2 x sockets on a 16 amp mcb, again verifiable in the brb so no opinion need.

What you are doing flukey is saying how you would do it, which was definatly not the op.

read my reply, acceptable but not good pactice my opinion

No **** that is what he got!!

So how comes MI is a different ball game, but SWA with it's higher CCC is not? Surely the same rules apply?

1.5mm MI (bare and exposed to touch, as it would be in this situation) = CCC of 23A light duty and 25A heavy duty clipped direct and 25A light duty and 26A heavy duty on tray.

1.5mm SWA 70 deg c (thermoplastic)= 21A clipped direct and 22A on tray.

1.5mm SWA 90 deg c (thermosetting)= 27A clipped direct and 29A on tray.

Most of the time nowadays I find that SWA is thermosetting insulation, and so the 27A CCC would be the one to look at. Which is better than even the heavy duty MI by 2A... So, with respect, how is MI a different ball game?



P.S. I was being quiet Flukey, but you just wouldn't let it lie!

im not playing pevvers, you can read MY opinion

 

[pevvers]

But why is MI a different ball game?

I'm not playing either, just curious how it's acceptable for a cable with a lower CCC to be okay to use, but one with a higher one isn't acceptable??

 

[flukey]

But why is MI a different ball game?

1.5 MI is a direct replacement for 2.5 t/e in nearly all situations, but then you would know that.

you have my opinion and no matter how hard you try you wont change it because thats the way I do it

i have never said its not acceptable, read my posts, just not what i would do

 

[pevvers]

Ah, but it has been fun, has it not?

Just realised you only live about 3 minutes drive from me, we should go for a beer and discuss it further!!

 

[Mac]

Ah, but it has been fun, has it not?

Just realised you only live about 3 minutes drive from me, we should go for a beer and discuss it further!!

Thank God for that

 

[flukey]

Ah, but it has been fun, has it not?

Just realised you only live about 3 minutes drive from me, we should go for a beer and discuss it further!!

beer sounds good, discussing this further doesnt

where are you based then

 

[pevvers]

I was only joking about the futher discussions....

I'm in Broomfields in Pitsea, but I won't be stealing any business from you as I'm not on the tools anymore!

 

[Modernelectric]

but would that be 4 or a 5 percent beverage? 4 would definately seem like bad practice to me. answers on a postcard

 

[pevvers]

Oh, the higher the percentage the better in my eyes!! Gotta be at least 5...

 

[flukey]

I was only joking about the futher discussions....

I'm in Broomfields in Pitsea, but I won't be stealing any business from you as I'm not on the tools anymore!

just down the road from me then, im in pitsea too, small world

im open to any further discussions, just dont question my methods as theyre mine not yours

definitely 5 per cent beer for me too

 

[Ralph Bradder]

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

I would use 2.5 for 2 sockets radial

 

[Deleted account]

I’ve done it again. In agreeing and liking a thread that is 12 years old. I wasn’t a member 12 years ago.

 

[Timbo]

You got me going there, Pete.

 

[ipf]

You got me going there, Pete.

I see 'pete999' wants more info from a 12 year old #2.

Come on mate.........!

Newbie #73 ?

 

[john masterson]

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

But a 1.5mm would be fine,

I have a shed [aprox 20 m long] supplied by a swa 1.5 mm coming off a household unit that will only accept domestic 3 pin plug fuses in it, so it is fused at 13 amp & perfectly acceptable by all the posts here. just wondering as my wife does tend to overload things [heater + tumble dryer etc] the fuses have blown before

 

[partplonker]

I have a shed [aprox 20 m long] supplied by a swa 1.5 mm coming off a household unit that will only accept domestic 3 pin plug fuses in it, so it is fused at 13 amp & perfectly acceptable by all the posts here. just wondering as my wife does tend to overload things [heater + tumble dryer etc] the fuses have blown before

This is a zombie thread. All that matters is that the overcurrent protection for your 1.5mm2 SWA is appropriate for its current carrying capacity based on reference method. Table 4D4A has the CCC of your cable at 21A when clipped direct, or 22A when buried in the ground. Your breaker/fuse needs to be rated lower than this.