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:

 

[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.

 

[Lucien Nunes]

a bit of 2H10

*No protection required
*Chase with a finger chisel
*Includes 24mm² CPC
*45mm bending radius
*Stays where you put it unlike those huge black plastic snakes that leap up and bite you

Or 2H16 up to 100A

 

[jackhammerJIM]

As Dillb said drill down at an angle to get you under the floor . On this job i stitch drilled out a 3rd of a brick on a downward angle . If the existing gas meter had been in a recessed box i would have followed suit .

 

[7029 dave]

*No protection required
*Chase with a finger chisel
*Includes 24mm² CPC
*45mm bending radius
*Stays where you put it unlike those huge black plastic snakes that leap up and bite you

Or 2H16 up to 100A

2H16 is the biggest ive done, 19L1.5 in multi.

 

[bigspark17]

View attachment 30528View attachment 30529


As Dillb said drill down at an angle to get you under the floor . On this job i stitch drilled out a 3rd of a brick on a downward angle . If the existing gas meter had been in a recessed box i would have followed suit .

Waw have you really installed another meter box next to dno box! If you have that is shocking imo. Put ur switch fuse in the dno box, if its on. The owners property its theirs not dno so you may add your sw fuse in there! Flobbogasted at that pic!!

 

[Simonslimline]

Waw have you really installed another meter box next to dno box! If you have that is shocking imo. Put ur switch fuse in the dno box, if its on. The owners property its theirs not dno so you may add your sw fuse in there! Flobbogasted at that pic!!

Looks like a gas box not electric.

There is a G written on it.

 

[bigspark17]

So its comon practice to mount isolator armoured and ipbox in a gas meter chamber??

 

[Simonslimline]

So its comon practice to mount isolator armoured and ipbox in a gas meter chamber??

I think you have misunderstood what Jackhammer wrote to be honest.

 

[uksparks]

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

It would be poor design to have no discrimination between the DNO fuse and the one you put in. It would be best to leave s gap of one fuse size so take it to 63A. Are you suggesting that it's ok to have two 100A fuses in line? Yes it might well protect the cable but it's not a great idea.

its not irrelevant.

 

[bigspark17]

It would be poor design to have no discrimination between the DNO fuse and the one you put in. It would be best to leave s gap of one fuse size so take it to 63A. Are you suggesting that it's ok to have two 100A fuses in line? Yes it might well protect the cable but it's not a great idea.

its not irrelevant.

Excuse me? So your suggesting using dno full capacity in one post then slating use of it in another.? Why is it bad practice fusing your submain at same as dno cutout on a capable ccc cable,? Can u explain?

 

[davesparks]

So its comon practice to mount isolator armoured and ipbox in a gas meter chamber??

No, the gas meter is in the gas box, the switchfuse is in the electric box waiting for a supply to be installed