Should garage have secondary consumer unit? + Best way to extend power from garage to shed?

[haggis999]

A dedicated 20A type C MCB located in the consumer unit in my house feeds power to my detached brick-built double garage via an underground armoured cable. This MCB is one of a group that is controlled by an 80A RCD.

There is no additional MCB protection within the garage. The incoming armoured cable simply connects to a fused spur, from which there are two output cables, one to feed a lighting circuit and one to feed a double 13A socket. I am assuming that this met all the regulations when the garage was built around 30 years ago.

I have three questions.

• Is my garage wiring still considered acceptable or should I really have a secondary consumer unit in the garage with separate MCBs for lighting and power?
• Would the answer to my first question be different if I wanted a second double 13A socket in the garage?
  
• What would be the best way to extend power from the garage to an adjacent wooden potting shed? I would want the shed to have lighting and one double 13A socket.

I will be getting a local sparky to do this work, but I want to be certain that he (or she!) does things in the correct manner.

 

[Pete999]

A dedicated 20A type C MCB located in the consumer unit in my house feeds power to my detached brick-built double garage via an underground armoured cable. This MCB is one of a group that is controlled by an 80A RCD.

There is no additional MCB protection within the garage. The incoming armoured cable simply connects to a fused spur, from which there are two output cables, one to feed a lighting circuit and one to feed a double 13A socket. I am assuming that this met all the regulations when the garage was built around 30 years ago.

I have three questions.

• Is my garage wiring still considered acceptable or should I really have a secondary consumer unit in the garage with separate MCBs for lighting and power?
• Would the answer to my first question be different if I wanted a second double 13A socket in the garage?
  
• What would be the best way to extend power from the garage to an adjacent wooden potting shed? I would want the shed to have lighting and one double 13A socket.

I will be getting a local sparky to install the connection to the shed, but I want to be certain that he (or she!) does things in the correct manner.

What size is the SWA feeding the garage socket? Would be better advised to get an Electrician to design the garage installation

 

[Taylortwocities]

As things stand, all is OK. Nothing to change there.
You could add a second socket using the correct cable.
Remember the maximum total load will be 20amp.

Adding cabling to the shed is, with respect, a job for an electrician.
He/she will need to assess the loads. It is at this point that a mini consumer unit might be appropriate. and he/she would need to determine the correct route/type of cable for the extension to the shed.

I want to be certain that he (or she!) does things in the correct manner.

Get yourself a registered electrician. This is notifiable work as the shed would be a new circuit.
Registered electricians are supposed to be competent and are checked every year. So they are supposed to do things in the correct manner, and to provide the correct certificates on completion.

 

[haggis999]

What size is the SWA feeding the garage socket? Would be better advised to get an Electrician to design the garage installation

I've not yet made any attempt to check the size of the SWA cable feeding the garage.

A local registered electrician has already given me a quotation to extend power from the garage to the shed, by simply installing a new SWA cable from the back of the existing garage socket. I'm just trying to make sure that there are no disadvantages for the job to be done this way.

 

[haggis999]

Adding cabling to the shed is, with respect, a job for an electrician.
He/she will need to assess the loads. It is at this point that a mini consumer unit might be appropriate. and he/she would need to determine the correct route/type of cable for the extension to the shed.

The loading in the shed will be minimal. Lighting is the primary requirement. The power socket is more of a just-in-case item and is unlikely to get much use. The only serious bit of electrical equipment that gets used in the garden is a big Nilfisk power washer (230v 2.9kW) and that would normally be connected to the garage socket or an external socket mounted on the wall of our house.

I am assuming that if there was a secondary consumer unit, that would be installed in the garage rather than the shed. Is that correct?

 

[Pete999]

I've not yet made any attempt to check the size of the SWA cable feeding the garage.

A local registered electrician has already given me a quotation to extend power from the garage to the shed, by simply installing a new SWA cable from the back of the existing garage socket. I'm just trying to make sure that there are no disadvantages for the job to be done this way.

You need to bin thie electrician who said just run a new SWA from the existing Garage socket, what you need is a professional Design done by a competent Electrician.
Without eyes on it's dificult to analyse properly, but as I see it from a distance, you need to make sure the SWA feeding the Garage is large enough to cope with the increasing loads, it is then you will require a Garage CU with 3 ways to accomodate the lighting circuit, and socket outlets in the Garage and 1 way to give you a supply to the socket in the shed.
Of course all this is subject to sizing and providing the correct OCPD in the house CU, and ensure that the Garage and shed do not require any Bonding, on top of this the Electrician you employ will need to check that there is adequate Bonding to the Water and Gas supplies to your House, it's all very well getting Bill the Sparks from the Boozer to do the work, but ask yourself the questions, is it correct is it safe, will it be certified, will there be any testing done followed by he correct Part P certification, not easy is it? Think on haggis999.

 

[haggis999]

... it's all very well getting Bill the Sparks from the Boozer to do the work, but ask yourself the questions, is it correct is it safe, will it be certified, will there be any testing done followed by he correct Part P certification, not easy is it? Think on haggis999.

I'm not entirely clueless on these matters, having personally rewired all three of the houses we have occupied over the past 47 years. The current house was done just before Part P came in and I had my work checked by an inspector from our electricity supplier (he said I had done a good job). I also obtained a degree in electrical engineering a very long time ago, just after electricity was invented.

However, I'm not up to date with the current Regulations and have no intention of seeking Part P certification. Hence my plan to employ a registered sparky for the very first time in my life.

It is just because I am cautious about such matters that I am questioning the advice I was given by the one electrician I have contacted so far. BTW, I found him via Checkatrade rather than the local boozer!

 

[Gavin John Hyde]

I found him via Checkatrade rather than the local boozer!

There we are folks... I am sure a lot of people on there are competent, safe and know what they are doing but I also know some people had out a bunch of reference cards to their mates to fill in and then get on the site after paying the high annual fee!

 

[Ian1981]

As long as your new proposed loading isn’t greater than 4600 watts and the swa is sized and all other existing cables with regards to the loading and over current protective device your good to go as I’m sure the electrician has factored in all the necessary requirements of the regulations.

 

[Octopus]

My advice is to ask around your local friends and neighbours and see if you can locate a spark this way.

Check-a-conman have some very dubious members with rather "false" ratings and reviews. Its also worth noting that Check-a-conman will almost never act on a complaint.

 

[HandySparks]

There's no requirement for an additional consumer unit. For small sheds with minimal loading and no bonding requirements, a 20A RCD protected supply to the sockets with a 3A FCU for the lights is my default suggestion. Sometimes I'll add a 20A DP switch where the supply enters the shed, but not essential. No need to over complicate it.

Subject, of course, to all the usual cable sizing calcs.

 

[Pete999]

My advice is to ask around your local friends and neighbours and see if you can locate a spark this way.

Check-a-conman have some very dubious members with rather "false" ratings and reviews. Its also worth noting that Check-a-conman will almost never act on a complaint.

Should that Choose-a-Conman? no I suppose Check a Conman-will-do, no I know Con-a-Customer that's better.

 

[MDJ]

I'm not entirely clueless on these matters, having personally rewired all three of the houses we have occupied over the past 47 years. The current house was done just before Part P came in and I had my work checked by an inspector from our electricity supplier (he said I had done a good job). I also obtained a degree in electrical engineering a very long time ago, just after electricity was invented.

However, I'm not up to date with the current Regulations and have no intention of seeking Part P certification. Hence my plan to employ a registered sparky for the very first time in my life.

It is just because I am cautious about such matters that I am questioning the advice I was given by the one electrician I have contacted so far. BTW, I found him via Checkatrade rather than the local boozer!

--------, I don't believe a single word of this post, your asking for advice so you can do the job yourself, do you think we are Idiots here?

 

[Pete999]

********, I don't believe a single word of this post, your asking for advice so you can do the job yourself, do you think we are Idiots here?

Just read the first post MDJ, "had my work checked by the electricity supplier", "and he said I had done a good job" must admit my alarm bells are ringing now.

 

[MDJ]

Yes Pete, we have him sussed out, he might think were Idiots but we have outed him, lol, I wasn't born yesterday.

 

[Pete999]

Yes Pete, we have him sussed out, he might think were Idiots but we have outed him, lol, I wasn't born yesterday.

Nor me.

 

[Pete999]

Yes Pete, we have him sussed out, he might think were Idiots but we have outed him, lol, I wasn't born yesterday.

Nor me. if we both carry on like this do you reckon we will both get outed?

 

[MDJ]

LOL, probably

 

[uksrevivor]

Haggis you seem to have given to much away here as no qualified electrician will attach an swa cable to the back of an existing socket in the shed. You have stated you have rewired your own houses before so the post stinks of you doing a DIY jobby on this and i dont think anyone will advise further but i might be wrong, i think the only advice from here is....
1 Support Pompey football club lol
2 Get a proper electrician in who will assess all the loads and test and inspect the installation before any work and will certify his work after completion as this is a notifiable installation.

 

[Deleted member 26818]

You say there is an FCU in the garage, is it an FCU or does it have a switch (SFCU)?
I would not extend the circuit from the socket in the garage, but from the supply side of the SFCU.
I would then use another SFCU in the potting shed to supply the light and the socket, same as in the garage.
Adding another socket in the garage would not be a problem.
This work would not require notification to Building Control.
Installing a CU in the garage however, would require notification.