New Outside power and lighting Circuit

[joolzhaines]

Hi,

I have asked an electrician to give me a quote for installing a new external power and light to a shed and power and light to an open patio area and have a few concerns with his proposal and wanted a second opinion

1. He wants to run 30mm cable to both areas which seems very large cable for a couple of lights and plug sockets, I would have though 10cm would be enough
2. He wants to put a RDC fuse box in the shed and patio area to feed to sockets which I think is overboard? The main consumer unit has RCD’s already and the new circuit will be on its own MCB covered by a RCD
3. Will having a fuse box with RCD mean that if there is a fault outside it will not trip the house RCD?

Thanks for your advice I just don’t want to get ripped off for work that is not needed.

Regards
Joolz

 

[Philpot]

Hi First ask to see his ID card and check who he is registered with and his qualifications.
Second check his quote as the cable sizes don't make sense you may have misread the sizes.
Or alternatively you may be asking us what you should be doing?
Philpot

 

[JUD]

1. Are you sure you've read it right. 30mm² isn't a standard cable size so seems a bit odd. How far is it to the shed/patio area from the consumer unit in the house?

2. It is good practice to put in a separate CU to prevent a fault in the shed/patio area from taking out circuits in the house. This would normally be fed from a non RCD protected circuit breaker (if RCD present at second CU) or RCBO in the main CU.

3. See above.

 

[joolzhaines]

Hi,

Shed is about 5 meters away and the patio is about 10 meters, I think he said he was using this cable just incase of future exspasion, what cable size should he be using as I will ask him about this.

Regards
Joolz

 

[mickys86]

Hi,

Shed is about 5 meters away and the patio is about 10 meters, I think he said he was using this cable just incase of future exspasion, what cable size should he be using as I will ask him about this.

Regards
Joolz

The cable size all depends on the requirement of what the design circuit will be. One socket and a few low energy lights probably means that 2.5 would be ok. It really does depend on what your going to be using the sockets for and how many lights.

 

[mickys86]

If your serious about getting a decent electrician in then I would suggest either asking on here with your location, failing that, get two maybe three local quotes

( I'm not looking for work - I am PAYE for a company and legally would not be able to complete this work on the side)

 

[JUD]

Hi,

...what cable size should he be using as I will ask him about this.

Regards
Joolz

That would depend on circuit loads/lengths etc. but it will be nowhere near 30mm². I'd say 4mm² as a guess (6mm² at the most).

Need more information to be accurate though e.g. how many lights and their wattage etc.

 

[joolzhaines]

Hi,

The power is going to:

1. A patio area which will have one standard weatherproof power socket and a single weatherproof light. (distance about 10 meters from shed cu)
2. A new shed which will have one standard power socket and a single light. (distance about 10 meters from house cu)

The shed will have its own small consumer unit with RCD which gets its power from the house consumer unit which is about 10 meters away, this cu will then feed the shed and patio area

Regards
Joolz

 

[Guitarist]

If you don't trust the electrician you got the quote off, then get another. Very simple
It sounds more like you are asking how this job should be done....