cable run outside mini-trunking using T&E

[matt.leung]

i popped round today oo see a new client that is having a loft extention. The builders wil not go any further until the electrcis done.

They recently has a PIR done and i was reading over what needs to be done.

Because of where the fuse board is located which needs to be upgraded anyway, the only permitted route from the consumer unit to the loft will be surface mounted, as they have newly decorated and will not allow any chasing.

The client want me to come straight out of the consumer unit, thorough the front wall into the porch, and then straight up using trunking. For here upwards is easy, but i am not very keen at all about running cables outside up the wall in trunking, even though it is a porch (open porch).

the cables to be run is the loft ring and a new lighting circuit...

can i please have some advice about the running the cables in mini-trunking.

Would BC pass this or not...???

matt

 

[Andy™]

use conduit, or SWA

 

[ProDave]

Yes I would go with conduit. It's not very pretty, but conduit fixed to the outside of a wall is definitely okay.

you can, if very neat and careful (i.e no twists), get two 2.5 and one 1mm t&e in a 20mm conduit, but 25mm would be a better bet.

 

[NozSpark]

Why not run a 6.0mm sub main in 20mm conduit??

or if they don't want a second CU then a 20A socket radial in conduit & pick up the lighing off the upstairs lights?

 

[matt.leung]

the ring for the loft has already been ran by the builder. They want me to install the power up into the loft and install an accessable junction box.

the consumer will be changed as well...from a 4way bs3036 to a 10way....

 

[betty swollocks]

why not a 2.5twin&e in the conduit for a 20a radial,

enough for the loft sockets and you could add a fcu with a 3a fuse for the lighting.

alternately isnt there a way of splitting the upstairs ringmain and extending it perhaps up through an immersion cupboard if there is one,

i once did something similar with trunking behind and through some built in wardrobes in a bedroom

 

[PC Electrics]

Who's managing this project? They should be sacked. Someone with electrical design knowledge should have been involved with this project from the start.

And what's the builder doing running in cables without any supervision? Is he going to sign the design and installation sections of the EIC or is he expecting you to do that?

Why not run a 2.5mm swa up the wall (will look neater than trunking), make the sockets a radial (still possible even if a 'ring' has been run in) and add an fcu with 3A fuse for the lights. Put it all on an RCBO in your new 5+5+2 board.

As it'll be RCD protected anyway you could even use 2.5mm 3 core H07RN-F in black, clipped direct with black clips, for the slimmest neatest possible look.

This is 4mm, but your wholesaler should be able to supply 2.5 (try Edmundsons) for about

 

[Graham Lister]

Not sure why these people are telling you how to do your job but to me the best way would be either break into existing circuit under upstairs floors and bring into loft through a cupboard in trunking. Or run a new radial in same way. If it has to go on outside of house then swa or conduit as suggested. How big is this loft conversion? cant see it needing more than 13 amps up there.

 

[Evans Electric]

Lets see what your choices are for running a supply up the outside of the building.

1. SWA .

2. MICC. (expensive)

3. PVC conduit .

4. Galvo steel conduit. (expensive)

5. Whats wrong with the trunking idea ? Brown trunking to blend in with brickwork,trunk will protect cable from the sun.

6. FP200.

Why do you think BC would not pass it , they have no electrical knowledge.

 

[batty]

I would not take job on it really pee's me off when you get builders doing half a job and then expect you to certificate there work but they will never learn.

 

[matt.leung]

thank you all for ur advice...

the client wants me to start this tuesday, which is really pushing it... due to other work that i have on...

 

[bengie]

MICC will be the neatest and cleanest way of doing it by a long long way, tiny cable compared to any of the alternatives and not to mention if you get bare it will weather and go dark in colour.

you also need to be honest and upfront about the work already done by the builder needing to checked over fully and how its a no no.