SWA, T&E or tails??

[HappyHippyDad]

Evening all..

I am currently doing my first full rewire. The customer is having the wall knocked down with the meter/cutout and CU on it. the plan was to move the CU under the stairs and get DNO to move the supply to the same place. They have said they cannot move the cutout to where the CU will be. The approx length from cutout to CU will now be around 8m so I need to add a fused switch. My questions are about which type of cable to use:

1. I could use 2 core 25mm SWA (seperate 16mm earth) but I am unsure of how easy this is to bend through the route? It will be going straight up from the meter box and then 90degress into the house wall entering directly under the first floor floorboards. What is the best way to get it through the wall without putting too much strain on it (with regards bending angle)?

2. BS7671 states 25mm to be used, however I am fusing down to 80A, could I not use 16mm SWA as CCC is 87A?

3. Could I use tails as at no point will the tails be buried in the wall. They will be going directly under the floor boards from outside the house (suitable protected outside) and then down from the ceiling directly behind the new CU (there will be a cavity behind new CU as I will bring out from the wall). Do they need to be protected if they are not getting buried in the wall?

4. Which is easier to move around/use T&E (16mm or 25mm), SWA (16mm or 25mm) or tails?

5. Which is the best fused switch to use? KMF, wylex metal? Can I gland SWA into a KMF or does it need an adaptable box?

Cheers chaps:biggrin:

 

[Simonslimline]

T&E only goes up to 16mm with a 6mm cpc.

 

[Octopus]

I would go down the SWA route then you don't have to worry about RCD protection... where ever you run them.

 

[Deleted member 26818]

I wish I could find in BS7671 exactly where it states 25mm needs to be used?
I seem to remember that some DNOs would move a cut out a short distance if the consumer was disabled?

 

[NDG Elecs]

I would preferably use 16mm 2 core SWA, fused down as you say. Never been keen on tails over such lengths running through a buildings fabric. You will be able to find out bending radii of the SWA online. The bigger casing on the Wylex switch fuses makes it a lot easier to terminate into. These ones:

Might be a bit of a swine to pull the SWA through though.

 

[Octopus]

I wish I could find in BS7671 exactly where it states 25mm needs to be used?

Its the pretty pictures in the OSG that most people refer to..... but I would say good practice.

 

[Andy78]

Evening all..

I am currently doing my first full rewire. The customer is having the wall knocked down with the meter/cutout and CU on it. the plan was to move the CU under the stairs and get DNO to move the supply to the same place. They have said they cannot move the cutout to where the CU will be. The approx length from cutout to CU will now be around 8m so I need to add a fused switch. My questions are about which type of cable to use:

1. I could use 2 core 25mm SWA (seperate 16mm earth) but I am unsure of how easy this is to bend through the route? It will be going straight up from the meter box and then 90degress into the house wall entering directly under the first floor floorboards. What is the best way to get it through the wall without putting too much strain on it (with regards bending angle)?
You would need to chase the brick out a bit to follow the bend then seal afterwards. Bending a cable that size isn't too much trouble with a couple of weetabix for brekky. I would be taking it down and under the ground floor as first choice though.

2. BS7671 states 25mm to be used does it ?, however I am fusing down to 80A, could I not use 16mm SWA as CCC is 87A? which table are you using for this data ?

3. Could I use tails as at no point will the tails be buried in the wall. They will be going directly under the floor boards from outside the house (suitable protected outside) and then down from the ceiling directly behind the new CU (there will be a cavity behind new CU as I will bring out from the wall). Do they need to be protected if they are not getting buried in the wall? Use SWA

4. Which is easier to move around/use T&E (16mm or 25mm), SWA (16mm or 25mm) or tails?

5. Which is the best fused switch to use? KMF, wylex metal? Can I gland SWA into a KMF or does it need an adaptable box? KMF will not accept a gland so you will need an extra box. Metal clad unit is less fiddly.

Cheers chaps:biggrin:

Remarks in red

 

[Plonker 3]

To make bending the SWA easier, simply drill the hole through the wall on a angle.

 

[amlu]

https://www.tlc-direct.co.uk/Products/CGFS100.html
fitted a couple recently, solid metal box with 32 and 25mm holes on top and bottom. value for money.

 

[HappyHippyDad]

I wish I could find in BS7671 exactly where it states 25mm needs to be used?
I seem to remember that some DNOs would move a cut out a short distance if the consumer was disabled?

ok, ok smarty pants! That OSG does have a lot to answer for!

To make bending the SWA easier, simply drill the hole through the wall on a angle.

Simple!! Cheers Dillb.

 

[Risteard]

Which is the best fused switch to use?

I presume you mean a switch fuse rather than fused switch.

 

[bigspark17]

3- if at no point do the tails go buried in wall tails all the way! Still need a metal switch fuse being greater than 3M from meter! Is under stairs best design place for cu? What height will it be?

 

[ipf]

Oh the woes of today......... what's wrong with a bit of 2H10 and a big mallet :wink5:

 

[uksparks]

Personally I would rather move the board so it's closer to the cutout so that i didn't have to fuse it down, I would rather have the capacity in the supply should I want to add juicy appliances.

 

[richy3333]

3- if at no point do the tails go buried in wall tails all the way! Still need a metal switch fuse being greater than 3M from meter! Is under stairs best design place for cu? What height will it be?

Have to agree. I'd never put a CU under the stairs. It's just isn't a good design.

 

[richy3333]

Evening all..

I am currently doing my first full rewire. The customer is having the wall knocked down with the meter/cutout and CU on it. the plan was to move the CU under the stairs and get DNO to move the supply to the same place. They have said they cannot move the cutout to where the CU will be. The approx length from cutout to CU will now be around 8m so I need to add a fused switch. My questions are about which type of cable to use:

1. I could use 2 core 25mm SWA (seperate 16mm earth) but I am unsure of how easy this is to bend through the route? It will be going straight up from the meter box and then 90degress into the house wall entering directly under the first floor floorboards. What is the best way to get it through the wall without putting too much strain on it (with regards bending angle)?

2. BS7671 states 25mm to be used, however I am fusing down to 80A, could I not use 16mm SWA as CCC is 87A?

3. Could I use tails as at no point will the tails be buried in the wall. They will be going directly under the floor boards from outside the house (suitable protected outside) and then down from the ceiling directly behind the new CU (there will be a cavity behind new CU as I will bring out from the wall). Do they need to be protected if they are not getting buried in the wall?

4. Which is easier to move around/use T&E (16mm or 25mm), SWA (16mm or 25mm) or tails?

5. Which is the best fused switch to use? KMF, wylex metal? Can I gland SWA into a KMF or does it need an adaptable box?

Cheers chaps:biggrin:

HHD have the DNO explained why they won't move the supply? I've had similar things done. They normally take their cable back to the outside so the joint is 'accessible', joint a new section that is then long enough to reach the new point required. Recently had this done on a 3 phase supply into a house, the new run was about 5 meters.

 

[bigspark17]

Personally I would rather move the board so it's closer to the cutout so that i didn't have to fuse it down, I would rather have the capacity in the supply should I want to add juicy appliances.

Dont see how its relevant as op has stated db is gunna be 8M away so irrelevant! If you use a cable capable of taking the dno full service fuse isolate it at that rating

 

[HappyHippyDad]

HHD have the DNO explained why they won't move the supply? I've had similar things done. They normally take their cable back to the outside so the joint is 'accessible', joint a new section that is then long enough to reach the new point required. Recently had this done on a 3 phase supply into a house, the new run was about 5 meters.

I dont think its set in stone that the supply will be moved to the outside, but I think its highly likely as that will be a much cheaper option for the customer. He may have to pay me more to extend the tails/SWA but I expect western power would have charged a great deal more than myself! The DNO options are to move it outside (outside wall is approx 30cm away from present supply) or to move it approx 6-7m (I think 8m was an exaggeration!) to the middle of the house.

 

[HappyHippyDad]

With regards point 3, which is easier to manipulate.. SWA or tails? I'm assuming tails bend a little more than the equivalent sized SWA?

 

[bigspark17]

Tails far easier and far easier to terminate! Have you not done much with tails or swa? This is pretty everday stuff for a spark id of thought.