Cable in Conduit and Junction Box

[Antscran]

Hi All,

Going to replace an existing garden supply from the consumer box which has been switched off and made safe, the cable previously used is a 4mm standard PVC which was run down the garden to a garage 20m away. The garage is old and needs to be torn down at a future date so I don't currently need a supply there, yet.

I will be laying a new patio soon and buying 63mm O/D conduit to lay under the patio to have a supply 5m (total run 13m from consumer unit) from house attached to a new garden wall, there will just be a few lights running off this supply as I have another external socket I use to power the lawnmower and strimmer.

Planning on using 6mm SWA which hopefully provides the option to extend the cable from a junction box fitted to the new garden wall with a 2nd run all the way to the garage in future for a small workshop and possibly solar.

I will have an electrician do the work obviously and just looking at options now before engaging services, if the supply had to be exclusive for the garage I could disconnect the lights in the future if necessary. Are there rules for extending cables as junction boxes will increase the voltage drop slightly?

Thanks,
Ant

 

[oldbutnotdead]

You need to talk to your electrician now and get him/her involved in the design phase.
If your 'solar' plans involve feeding in to the grid then I don't think you'll be able to use that load cable as a back conductor.
How deep are you planning on burying this conduit and what covers it where it emerges from under the patio?
A properly made off joint can be assumed to have zero impedance so can be ignored for volt drop purposes. It would be a foolish design to specify a cable that only just met the criteria on a setup like this (where the cable cost is an insignificant fraction of the overall job cost).