shed wiring

[musicalbaz]

Hi! We are having electrics installed in our new shed containing 4 twin sockets and 2 lights. 2 contractors have given us 2 different plans!
One is to use Steel Wire cable to the shed with various joints etc and the other to use underground plastic conduit and 6mm pvc cable. Help! We are confused!
Which is the best method and safest? The shed is 25m away from house.
Many thanks!

 

[plugwash]

using plastic conduit with indoor grade cable inside to run underground is a bad idea because you don't have the earthed metal layer for protection if it gets dug through.

SWA is the normal way of running outbuilding power. Split con is cheaper but far more vulnerable to N-E faults (the recs use split con a lot for TN-S supplies but they don't care about N-E faults). Pyro is generally thinner and neater and may last longer (noone really knows how long modern plastics will last) but its more expensive and its far more important to get the terminations right. Steel conduit or kopex are also possible but rarely used for cost reasons.

 

[musicalbaz]

Hi!
Yeah, many thanks! Our original contractor says Steel cable option to be the best. Does it really have to be buried though? The wifes` not impressed with `em digging up the borders!! Can it be surfaced layed? Thanks!

 

[Spark123]

It is open to opinion which is the best way, both systems are acceptable as long as the plastic conduit method is sufficiently strong enough to withstand likely mechanical damage. In my opinion though, I prefer SWA for underground systems as I think it offers better protection.

 

[plugwash]

i'd be very surprised if plastic conduit could protect against a sharp spade or small digger.

its not idea to have the stuff on the surface as it makes it within easy reach of accidental damage by garden tools etc.

 

[musicalbaz]

Ok guys, many thanks! Glad i found this forum, just checking i wasn`t getting fobbing off by contractor sales talk!!
Thanks for all advice.