External Garage / Workshop Electrics.

[Carl1973]

I have to run a power cable from my house to garage, the distance is approximately 12 M.

It would be a pain to bury the cable due to the distance also being concreted. I am aware that over that distance it should be 3.5m high and supported on a catenary wire but it is not practical due to the height of the garage..

Are there any other solutions?

I would also like to run a further power from the garage to a workshop further down my garden, this can be buried easily enough but any suggestions on how to link the power would be appreciated so I am aware of what it entails.

Thanks in advance.

 

[Taylortwocities]

Before you start.

What will be the total maximum demand (in amps) for the garage plus workshop?

No point doing anything until that is established. From that information you will need to calculate the size of cable that you need.

 

[Carl1973]

Garage will be two strip lights and just a single double socket to be used for the odd powertool and possible welder...

Workshop will be set up with similar lighting. and 3 double sockets for a table saw, chop saw, router etc....

The garage electrics would not really be in use whilst in the workshop and vice versa..

I am also rubbish at multi-tasking so short of a battery being on charge and 1 power tool running that would be about the maximum load but I am not sure what each item would draw..

 

[PrenticeBoyofDerry]

It would be a pain to bury the cable due to the distance also being concreted. I am aware that over that distance it should be 3.5m high and supported on a catenary wire but it is not practical due to the height of the garage..

Are there any other solutions?

Solar power, wind turbine, hydro etc..
So in short if you do not have a solid structure to fit to, such as a wall (not a fence) they are about your only options

 

[Carl1973]

So in short if you do not have a solid structure to fit to, such as a wall (not a fence) they are about your only options

So I bite the bullet and channel out the concrete to run it sub-surface....

would it be practical to run it from a 45A RCD in the house to a Garage Consumer Unit in the Garage and out of that to a Garage Consumer Unit into Workshop..

What size / type of cable would be recommended.

 

[Taylortwocities]

would it be practical to run it from a 45A RCD in the house to a Garage Consumer Unit in the Garage and out of that to a Garage Consumer Unit into Workshop..

With respect, that one sentence indicates that you do not have the skill needed to design, install and test this NEW CIRCUIT. This would need to be notified to the local authority before you start work.

You mention 45A RCD. But I never did see such a thing. A 30mA RCD, yes. A 45A MCB, yes. There are also 45A 30mA RCBOs.

What would this device be for?
\

 

[Carl1973]

I got my my TLA's muddled, but I didn't post on here to be ridiculed...

Work will be done by a part P qualified electrician, I was just doing my homework!

I'll just go elsewhere..

 

[Taylortwocities]

Fair enough, but your electrician will have to sign a certificate that says that HE/SHE designed, installed and tested the installation.

HE/SHE will also know that the CPD at the origin is there to protect the cable. So the size of the cable has to be determined before anyone thinks about if the device should be a 6A or a 45A whatever.

For instance

possible welder

is a very broad brush indeed.
Some just plug in to a 13A socket, some need a much larger dedicated supply. You would still need CPDs with C or D curve so that they can withstand the inrush current.

There's lots, lots more to consider…

So, get your sparky to determine what you need, you won't get the answers from an Internet forum.

 

[ban-all-sheds]

I got my my TLA's muddled, but I didn't post on here to be ridiculed...

Then you won't have been disappointed.

Work will be done by a part P qualified electrician

In which case...

Are there any other solutions?

When you get electricians to come and quote for the job they may well have ideas, as they can see the environment and we can't

any suggestions on how to link the power would be appreciated so I am aware of what it entails.

That will be the electrician's design and construction decision.

would it be practical to run it from a 45A RCD in the house to a Garage Consumer Unit in the Garage and out of that to a Garage Consumer Unit into Workshop..

My advice would be to ask the electricians to quote for taking meter tails into a switchfuse and supply the outbuildings from there, not from the house CU.

What size / type of cable would be recommended.

The one chosen by the electrician who will be signing certificates to say that he did the design, that his work complied with the regulations etc.

I was just doing my homework!

OK - here's some for you, if you want to learn more about what's involved:

• 
  
  
  
• //www.diynot.com/wiki/Electrics:books
  
  
• //www.diynot.com/wiki/Electrics:MCBtoCable
  
  
• http://www.tlc-direct.co.uk/Book/4.3.1.htm (all subsections)
  
  
• http://www.tlc-direct.co.uk/Book/4.3.11.htm
  
  
• http://web.archive.org/web/20070327014113/http://www.kevinboone.com/cableselection_web.pdf
  
  
• http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html <- Specify 2-core cable and PVC, even if that is not what you are using or it will make invalid assumptions.
  
  
• http://www.tlc-direct.co.uk/Book/5.3.1.htm
  
  
• //www.diynot.com/wiki/Electrics:MCB2
  
  
• http://www.tlc-direct.co.uk/Book/7.13.3.htm
  
  
• http://www.tlc-direct.co.uk/Book/8.1.1.htm
  
  
• //www.diynot.com/wiki/Electrics:SWA_gland
  
  
• http://electrical.theiet.org/wiring-matters/16/elect-inst-outdoors.cfm?type=pdf
  
  
• //www.diynot.com/wiki/Electrics:Part-P
  
  The references above which are in italics are out of date. The principles are still valid, and you can absolutely learn valid things from them, but you will need to refer to the latest edition of the Wiring Regulations to get the correct data.

I'll just go elsewhere..

Going elsewhere won't alter the fact that the electrician you use has to be the one who does the design etc or he won't be able to certify the the work.