SWA For meter tails?

[Msitekkie]

I need to upgrade my meter tails to 25mm. The existing tails pass along under the pebble dash in plastic conduit (which would be too small), then apparently at an angle through the porch structure (unprotected) then turn sideways into a void & up the void to CU.

I have seen other posts where the use of SWA is suggested but I haven't actually seen SWA with 25mm cores. "25mm SWA" appears to be 25mm "Outside diameter", so I presume that means the cores are smaller.

Any suggestions as to the best approach welcomed. I actually think I will struggle with getting SWA through anyway even if it does exist with suitable cores, because of the bends involved.

NB The meter box is under the window of the house rather than on the side of the porch, but the void inside the porch is set back behind the run of the outside wall so it's not possible to drill directly through the outside porch wall into it.

 

[Msitekkie]

So he WILL break the seals then?

No seals being broken. I had an isolator fitted by my provider in anticipation, I'm not aware of it being fused however.

 

[Msitekkie]

Surely that is a job for the DNO?

DNO replace the fuse, but they won't do the tails to the CU.

 

[Msitekkie]

25mm SWA is common stuff for example
25.0mm² 6943X 3 core SWA Steel Armoured Cable

You will have some challenges with bend radius. I assume that you will (have already) a switch/fuse at the cut out end? Due to the length of the tails?

PS Why do you feel that an upgrade to 25mm is needed?

Thanks for the link. That's the cable I looked at first, but doesn't OD stand for outside diameter? How can that be 25mm if the individual cores are 25mm?

 

[Pete999]

Don’t forget the earthing conductor

Yes I was wondering about cable enclosure if I don't use SWA. Seemingly 25mm Conduit can be used, according to the cable factors.
16mm factor = 145
25mm Cable factor = 217 2x217 = 434
Total = 589
But I can't quite see how two 25mm cables fit in a 25mm pipe? Maybe something about the size of the cable I'm missing as I don't actually have any 25mm tails.

The cable are reffering to 25mm2 csa, not diameter

 

[Jim_e_Jib]

Thanks for the link. That's the cable I looked at first, but doesn't OD stand for outside diameter? How can that be 25mm if the individual cores are 25mm?

It does but as Pete999 says, the reference is to 25mm2 CSA SWA. It looks to be a happy coincidence of maths, manufacturing and electrical requirements that this 25mm2 SWA has a nominal OD of 25.1mm

 

[Pete999]

Don’t forget the earthing conductor

Yes I was wondering about cable enclosure if I don't use SWA. Seemingly 25mm Conduit can be used, according to the cable factors.
16mm factor = 145
25mm Cable factor = 217 2x217 = 434
Total = 589
But I can't quite see how two 25mm cables fit in a 25mm pipe? Maybe something about the size of the cable I'm missing as I don't actually have any 25mm tails.

The cable are reffering to 25mm2 csa, not diameter

 

[telectrix]

if he's got to fit switch fuse, he might be better off dropping to 80A SW/F and then using 16.0mm SWA. easier to install.

 

[Msitekkie]

It does but as Pete999 says, the reference is to 25mm2 CSA SWA. It looks to be a happy coincidence of maths, manufacturing and electrical requirements that this 25mm2 SWA has a nominal OD of 25.1mm

Some lights going on... That's really helpful thanks.
Led me to this CSA to diameter calculator page which may help someone else:
Cross-sectional area to diameter conversion circle intersection cross section diameter electric cable conductor formula wire diameter and wiring and calculation cross section AGW American Wire Gauge thick area of a solid wire formula conductivity resistivity stranded wire litz length current - sengpielaudio Sengpiel Berlin - http://www.sengpielaudio.com/calculator-cross-section.htm

 

[Msitekkie]

if he's got to fit switch fuse, he might be better off dropping to 80A SW/F and then using 16.0mm SWA. easier to install.

Not an option given I'm struggling to get diversity calcs down to 100A and I already have 16mm tails anyway.

 

[davesparks]

Not an option given I'm struggling to get diversity calcs down to 100A and I already have 16mm tails anyway.

You’re probably getting the calculations wrong then, the average house doesn’t need much more than about 20A.

Out of interest how did you arrive at a figure over 100A for a house?


Not knowing that conductors sizes are measured in CSA or that SWA is made in 25sqmm (and much bigger) and suggesting that 25mm tails could be installed in 25mm conduit show that you aren’t an electrician so why not employ one to do the job correctly and safely?

 

[Risteard]

As above the OP seems wholly incompetent to carry out this work. He needs an Electrician.

 

[Pete999]

Agree with the above posts, do yourself a favour and employ an Electrician to sort your problem out.

 

[Msitekkie]

Give a guy a break. If you looked at my profile you would see I'm a qualified electrician but still very new to the trade. I thought this forum was here to help people like me who are still learning, rather than knock us down. If people can't be open and ask questions that might show they are inexperienced then it rather limits the usefulness of such forums. I'm already aware I lack practical experience and have been trying to find someone with more experience I can work with as an Electricians Mate to remedy that. In the meantime I turn to you guys... As it happens I probably am going to involve someone with more experience on this one, as no answers from anyone on the routing question, although I appreciate that's difficult to visualise on a forum such as this.
CSA may be obvious when you have been in the industry for years, but when you see a listing for 25mm SWA that specifies 25mm OD and makes no reference to CSA/core size alongside, it does raise a question mark in one's mind.

 

[Pete999]

Give a guy a break. If you looked at my profile you would see I'm a qualified electrician but still very new to the trade. I thought this forum was here to help people like me who are still learning, rather than knock us down. If people can't be open and ask questions that might show they are inexperienced then it rather limits the usefulness of such forums. I'm already aware I lack practical experience and have been trying to find someone with more experience I can work with as an Electricians Mate to remedy that. In the meantime I turn to you guys... As it happens I probably am going to involve someone with more experience on this one, as no answers from anyone on the routing question, although I appreciate that's difficult to visualise on a forum such as this.
CSA may be obvious when you have been in the industry for years, but when you see a listing for 25mm SWA that specifies 25mm OD and makes no reference to CSA/core size alongside, it does raise a question mark in one's mind.

Not in an Electrician's mind it doesn't, just checked your profile, those qualifications you have, are designed for practising Electricians, designed to update their knowledge. These courses do not make you an Electrician, if you were told that by the Training Schools then you have been duped.

 

[Andy78]

I've looked at your profile. There is nothing in there that indicates you are qualified in any meaningful sense as an electrician.

CSA is obvious to those that have been in the trade for ages, and also those new to the industry who have done proper training.