Certification needed to re-route outdoor power cable?

[gravesend46]

I had an existing power cable run from my house to an external garage when I moved in, all buried with SWA cable. I have now removed the garage and replaced with a garden office/log building.

The cable is in exactly the same place, I just need to renew the RCD and run the new cable for sockets and lighting into the new building. Would I need certification for this, or is it covered under "existing installation"...?

 

[syl]

What does renew the RCD mean? Are you placing a new consumer unit (or replacing an old one) in the new building, or replacing something inside an exiting unit at the new building or at the house end?

New circuits need official sign off. There is debate over what constitutes a new circuit (does a second CU fed from a primary CU feed a circuit or a sub circuit? What about an FCU, does that feed a circuit?). I suspect the biggest question is can you do what you want to do safely and test it to make sure it's safe? You might want to do some of the donkey work and get a professional to make some connections and do the appropriate tests (best to speak with them before you start).

 

[gravesend46]

Sorry, my terminology is probably all over the place (as you can tell, I wouldn't be carrying out this work myself, I have a competent friend who is an electrical engineer who would be doing this, I am just trying to establish what I need to do before getting him round).

The cable comes from the mains/CU in the house and did run to the garage where it entered a power breaker/RCD socket.

So the work being done is existing cable to new power breaker in new building, new wiring from there to lighting and sockets.

 

[xr4x4]

What size mcb/fuse is the circuit connected to in the cu?

Is the circuit rcd protected at the cu?

What size is the cable.

What load are you looking to put on the circuit.

How sockets, lights etc?

 

[gravesend46]

No, not protected at the CU (see here: http://i.imgur.com/PoYqdNF.jpg ).

Load-wise, just typical office equipment - two printers, maximum four laptops, a couple of screens.

Probably maximum three double sockets, security light and one or two fluorescent lighting tubes.

My main reason for getting the answers now is the guy doing the building is laying the floor on Monday and so wanted to arrange the cable beneath that. But thinking about it now, I can still arrange all the cable unconnected and plan the runs myself, then get electrician in for final wiring and the safety aspects, which is probably best reading here and elsewhere!

 

[xr4x4]

Easiest way will be to run the swa to a rcd protected cu in the new building and run the new circuits off that.

The swa cable doesn't need to be rcd protected, but your new circuits will need to be.

 

[Taylortwocities]

Would I need certification for this, or is it covered under "existing installation"...?

So, this is not a new circuit, but the works done to provide the new services in the "office" will need to be tested and certified as being compliant BS7671. This is true of all electrical work.

Load-wise, just typical office equipment - two printers, maximum four laptops, a couple of screens.

Are those computers going to keep you warm, or did you forget to factor in the 3KW fan heater? How will you make the coffee?

I have a competent friend who is an electrical engineer

An "electrical engineer" is NOT necessarily an electrician. An electrical engineer designs, builds and maintains electrical control systems, machinery and equipment.
JIB's definition of an electrician can be viewed HERE

THIS is an electrician at work: