to go TT or not

andekoch · Aug 29, 2010

Just thinking and want your opinions. I have to quote on a job which is a new house on a very large plot. The supply is currently a TNS to a point approx 10m from the house and a switch fuse plus armour takes the supply to the curret house.

The owner wants to build a new house and take a feed from the current meter to the house. Run is 40m of cable. Assume cable will be burried SWA.
I am wondering if I should go with 2 core SWA and make the house TT or go with 3 core SWA and leave it as TNS.

Roughly and using 3% volt drop it looks like the SWA is going to be around 35mm assuming a 100A load so an extra core is quite expensive not to mention making the cable dificult to handle. Calcs very rough so dont shoot me down yet.

I am currently thinking to go the TT route. What you guys think?

GStueyXR · Aug 30, 2010

andekoch said:
Just thinking and want your opinions. I have to quote on a job which is a new house on a very large plot. The supply is currently a TNS to a point approx 10m from the house and a switch fuse plus armour takes the supply to the curret house.

The owner wants to build a new house and take a feed from the current meter to the house. Run is 40m of cable. Assume cable will be burried SWA.
I am wondering if I should go with 2 core SWA and make the house TT or go with 3 core SWA and leave it as TNS.

Roughly and using 3% volt drop it looks like the SWA is going to be around 35mm assuming a 100A load so an extra core is quite expensive not to mention making the cable dificult to handle. Calcs very rough so dont shoot me down yet.

I am currently thinking to go the TT route. What you guys think?

I am thinking it would be cheaper to get DNO to install a service head than pay for the SWA

Guest123 · Aug 30, 2010

New house.....new connection.

What type of supply does the current house on the plot have???? single phase 100A max I'm guessing and you want to run another new house off it aswell??? Like Stuey, contact DNO and ask for new connection.

andekoch · Aug 31, 2010

sounds like a good option to me. easy to not see the wood for the trees. Will see what the DNO says if the job goes any further, any idea what they charge for a new connection, London area.