Electric to garage check list

[spider]

Hi everyone,

Please can some one well versed with supplying electric to garage/outhouse's double check my list of items and method.

Im planning on using 6kw @ 36a on 240v max in my garage ive made the below shopping list some of the items were freebies and i already have:

All items will be bought from screw fix if anyone wants to check them out just dump the item number into there sites search engine

1x item 30959 Volex 2-Way Fully Insulated RCD Board Consumer Unit

1x 16mm 50m PVC Cable - Grey /Brown which ill split into (2x 25m tails) ALL READY HAVE FOR FREE!

2x Volex Switch Socket DP 2G 13A

3x Volex 2G 29mm Surface Box

1x Volex 13A 2G SP Sw Skt

1x Prysmian 6491x 1-Core Green/Yellow 16mm

 

[Badger]

Hi everyone,Please can some one well versed with supplying electric to garage/outhouse's double check my list of items and method.

Im planning on using 6kw @ 36a on 240v max in my garage ive made the below shopping list some of the items were freebies and i already have:

All items will be bought from screw fix if anyone wants to check them out just dump the item number into there sites search engine

1x item 30959 Volex 2-Way Fully Insulated RCD Board Consumer Unit

1x 16mm 50m PVC Cable - Grey /Brown which ill split into (2x 25m tails) ALL READY HAVE FOR FREE!

2x Volex Switch Socket DP 2G 13A

3x Volex 2G 29mm Surface Box

1x Volex 13A 2G SP Sw Skt

1x Prysmian 6491x 1-Core Green/Yellow 16mm

 

[The Godfather]

Is 10mm SWA (3 core) not a better option here (rather than extended 16mm tails), it should be more than adequate for the load.

The Godfather

 

[M107]

In the additional holes to the Henley block ill connect 2x 16mm tails on the list above and run them to the garage

What size is the service cutout fuse 100A? not a good idea to use 16mm tails if so. I'd think about 25mm tails to a switch fuse then run 2 core 10mm swa to garage.

Finally ill use the 25m 16mm green earth cable and run that from the garage CU back to my main house CU and connect that to the ground terminal bar inside the house CU

Personal prefrence dont export pme (assuming the house is pme) but TT the garage & run the 16mm G/Y to a local earth rod at the garage..do not connect the garage cu to the house earthing system.

6mm T & E cable inside the garage CU to connect up the 3xdouble sockets, to do this i was just going to go into the first DP socket into the second DP socket and then finishing in the final SP double socket if that makes sense in series.

It's called a radial circuit....you'll have fun trying to terminate 2x 6mm into the terminals of the volex sockets.

 

[spider]

Hi Badger sorry for the late reply i work mostly nights so sleep through the days no mate im no sparky just a standard DIY'er who has basic knoledge of the electrical systems in a house im learning more as i go along thou thanx. Did you recommend armoured cable because of the possibility of the cable getting chinked or damaged? as tail's in flats run anything upto 50m at times so what would be the problem with 2x25m? if im going to use twin and earth as you recommended then i will have to go into a spare fuse in my house CU would i not or id end up with a earth wire in the cable coming from the Henley block? thanx

The Godfather ill search for some 10mm swa cable and see how much that can be bought for then it would be cheaper to use what i have now 2x25m 16mm tails but ill have to put them in an enclosure for safety so maybe swa like you stated is the right way to go better safer than anything else i guess.

Hi M107 when you say i shouldn't run 16mm cable from the fuse can you explain a little more why not to, as the cables going into a 63a rcd fuse anyway? i understand the part about the swa thou its a more sturdier cable thanx.

pme & TT sorry im terrible with abbreviations can you recommend somewhere where i can read about all the abbreviations but saying that i understand what you are trying to say better to setup a local earthing point at the garage than going back to the main house CU but just out of curiosity why can i not go back to the house CU is it just a regulation thing and generally not the thing to do but would it work?

I get what you mean its gonna be a tight squeeze in those volex sockets with 6mm but what other options do i have 2.5mm can't handle 40a even when doubled?

 

[spinlondon]

Are there any Extraneous-conductive-parts in the garage?

Do you intend exporting a TNCS/PME earth?

Have you notified the DNO?

Is there any reason why you cannot use a spare way in the House CU?

Why are you intending on using such large cable?

 

[M107]

I get what you mean its gonna be a tight squeeze in those volex sockets with 6mm but what other options do i have 2.5mm can't handle 40a even when doubled

Are you saying you want the socket circuit to be rated at 40amp ?

pme & TT sorry im terrible with abbreviations can you recommend somewhere where i can read about all the abbreviations

(from TLC website)

5.6.1 - What is protective multiple earthing?

If a continuous metallic earth conductor exists from the star point of the supply transformer to the earthing terminal of the installation, it will run throughout in parallel with the installation neutral, which will be at the same potential. It therefore seems logical that one of these conductors should be removed, with that remaining acting as a combined protective and neutral conductor (PEN). When this is done, we have a TN-C-S installation {5.2.4}. The combined earth and neutral system will apply only to the supply, and not to the installation.

Because of possible dangers with the system which will be explained in the following sub-sections, PME can be installed by the Electricity Supply Company only after the supply system and the installations it feeds have complied with certain requirements. These special needs will be outlined in {5.6.4}.

The great virtue of the PME system is that neutral is bonded to earth so that a phase to earth fault is automatically a phase to neutral fault. The earth-fault loop impedance will then be low, resulting in a high value of fault current which will operate the protective device quickly. It must be stressed that the neutral and earth conductors are kept quite separate within the installation: the main earthing terminal is bonded to the incoming combined earth and neutral conductor by the Electricity Supply Company. The difficulty of ensuring that bonding requirements are met on construction sites means that PME supplies must not be used. Electricity Supply Regulations forbid the use of PME supplies to feed caravans and caravan sites.

but just out of curiosity why can i not go back to the house CU

Well you can if you wish (called exporting pme) but if there are any extraneous conductive parts (such as metal frame / piped services) you run into hassel with bonding

So my personal prefrence is to TT outbuildings, but as said others do export PME.

Oh TT means Terra Terra (earth earth) and relates to the incomming supply earthing arrangements, so TT is saying the earthing is the earth (soil) hence you require a rod in the deck to connect the main earthing conductor to.

Hope that explains it a little for you.

you say i shouldn't run 16mm cable from the fuse can you explain a little more why not to, as the cables going into a 63a rcd fuse anyway

Yes the 16mm will be rated at 63a (taking other factors into account) but as you say it will be going from the henly blocks in to the 63amp rcd.....soooooo the only over current protective device protecting the 16mm (63amp) tails will be the big main suppliers fuse rated at (I hazzard a guess) at 100amp, so under fault conditions the tails will probably ignite before the fuse blows.

The Godfather ill search for some 10mm swa cable and see how much that can be bought for then it would be cheaper to use what i have now 2x25m 16mm tails

Put the 16mm tails on ebay or here on T.E.F then use the procceds to buy the 10mm (2core 10mm & use the armour as cpc... it'll be slightly cheaper)

 

[spider]

Hi spinlondon to answer your questions

No not really very clean and empty

not sure how to answer that one like i said don't know the abbreviations but from what ive said earlier possible export back to house CU but once i get a reply from M107 if there's a reason other than just regulation why this cant be done ill have no choice but to setup a local earth point at the garage.

No other than pulling the main 100a fuse

yes house CU is dated and small slots are full at the moh and i dont fancy an upgrade job at the moh would have to pay sparkie for it so tests ect can be done and that's something for the future!

its just the run mate its how fare out ill need them to go once there going round corners ect to be honest they might be 15m each im just saying 25m as its the max length they will be as in first post i was worried about voltage drop in that length but i don't think you would get any noticeable drop on anything 25m and under.

 

[spider]

Hi M107 allot off good information there thanx for the support can't believe i missed the 16mm coming from the Henley block really only 25mm should come from there that way the 63a rcd will fail protecting my sockets but the incoming 25mm wont burn that was a big mistake thanx for pointing it out.

yes if possible i need to be using around 36a at any given time from those sockets probably just one double to be honest but im planning on installing 3doubles for future use of smaller appliances just makes sense to have more sockets available.

so your saying do 25mm from henley to a cutout fuse then use swa to garage then 6mm to sockets!

or atleast use 25mm from henley to garage but swa is better.

 

[spinlondon]

If there are no extraneous-conductive-parts (water/gas pipe or metal structure) in the garage, then you won't be exporting the earth.

In which case you will only require a CPC (Circuit Protective Conductor) not a Main equipotential bonding conductor, so you won't require such a large size of earth cable.

Why are you intending on using 6mm

 

[a1spark]

Hi M107 allot off good information there thanx for the support can't believe i missed the 16mm coming from the Henley block really only 25mm should come from there that way the 63a rcd will fail protecting my sockets but the incoming 25mm wont burn that was a big mistake thanx for pointing it out.yes if possible i need to be using around 36a at any given time from those sockets probably just one double to be honest but im planning on installing 3doubles for future use of smaller appliances just makes sense to have more sockets available.

so your saying do 25mm from henley to a cutout fuse then use swa to garage then 6mm to sockets!

or atleast use 25mm from henley to garage but swa is better.

can't believe i missed the 16mm coming from the Henley block really only 25mm should come from there that way the 63a rcd will fail protecting my sockets but the incoming 25mm wont burn that was a big mistake thanx for pointing it out. ?:| ROTFWL

The RCD will probably have been installed for Fault Protection or Additional protection etc...it is not primarily related to the size of the tails.....more info needed !

What type of Earthing have you got back at the incoming mains point.?

How is the Garage supply to be routed from the mains position to the Garage/

Is the Garage detached from the house?

If some of the proposed loads are Fixed, then they should be wired on Radials from the Garage C.U.

If they are all on 13 A plugs then you cant run more than 32A off a Ring Final circuit......consider additional circuits !

What exactly are the appliances you intend to use.....do you intend to use them all at the same time ?

More advise when you have had chance to think about these points....

post back when ready

a1spark

 

[Dane]

what are you actually running in the garage?

 

[a1spark]

what are you actually running in the garage?

I suspert Spider may not be applying diversity to his loading.....he may simply be adding up all the loads he may well use in the Garage but not necessarily at the same time...Dunno though ..we will have to wait till his next post and see if we can help him out further !

a1spark

 

[SPECIAL LOCATION]

can't believe i missed the 16mm coming from the Henley block really only 25mm should come from there that way the 63a rcd will fail protecting my sockets but the incoming 25mm wont burn that was a big mistake thanx for pointing it out. ?:| ROTFWL The RCD will probably have been installed for Fault Protection or Additional protection etc...it is not primarily related to the size of the tails.....more info needed !

What type of Earthing have you got back at the incoming mains point.?

How is the Garage supply to be routed from the mains position to the Garage/

Is the Garage detached from the house?

If some of the proposed loads are Fixed, then they should be wired on Radials from the Garage C.U.

If they are all on 13 A plugs then you cant run more than 32A off a Ring Final circuit......consider additional circuits !

What exactly are the appliances you intend to use.....do you intend to use them all at the same time ?

More advise when you have had chance to think about these points....

post back when ready

a1spark

Ditto!!

all the above points!

There does seem to be a lot of misunderstanding of basic electrical circuit design going on with this project?

What overload protection is there going to be on these supply tails?

If more than 3m long IMHO will need its own isolator switch and fused overload protection.

e.g.

overload & shock protection are TWO different things..

a 63A rated 30ma RCD is NOT providing 63a overload protection..

Just 30ma shock protection with the ability to carry and switch off a 63A load without melting or arcing its own switch contacts!

Bit like a main switch rated at 100A, will NOT provided 100A overload protection!

its just capable of switching off a load of 100A without frying your fingers!

 

[spider]

hi everyone sorry about the late post been really busy and had to leave everything for awhile agreed sorry for the lack of information when posting this is my first electrical based question ive posted online so im not accustom to thinking like a sparky,

a1spark........ill try and answer your questions in the order you posted them

Not sure on the earth to be honest is there anything i can look for to let you know. All earth wires from radiators kitchen sink ect just head back to the main CU in house.

For the mains supply to the garage i was just going to go up into the loft then across and come down again into the garage.

No the garage is not detached its connected to the house but is at the up most distance away from the CU due to the orientation of the house.

Not sure what you mean by FIXED LOAD but A radial circuit from the garage CU terminating in the last socket is exactly what i had in mind.

hmmmm 32a from a double socket is all i can use so be it then one peace of equipment a welder/plasma torch i have runs off 36a ill just have to forget about it then and use 2.5mm to wire the sockets can the fuses in double sockets just not be swopped out for a higher rating??? and the cable size feeding them increased.

Appliances will be boggiest being an arc welder/plasma torch for sculpting (36a max) and at any time afterwards smaller appliances like tv games console, at a later date maybe a dryer as well ect. You were right i was adding up all the amps of everything i might use and was acting as if they would all be running through one 32a double socket i forgot i can just split things down over all 3 sockets doh with the exception of the welder.

SPECIAL LOCATION........ i agree i do have basic knowledge of electrics or to put it another way be cause ive never really had to do much with them for such along time im missing things as im not accustom to thinking like a spark but im learning every post, saying that thou i have contacted a friend local sparky to see if he can do it for me for a price but he hasn't replied yet so might end up still doing the job myself if i can get things cleared here first. Deffo going to use an isolator switch fuse ive sourced a 80A Fused Main Switch with 80A HRC Fuse 800 KMF for

 

[The Godfather]

Deffo going to use an isolator switch fuse I've sourced a 80A Fused Main Switch with 80A HRC Fuse 800 KMF for

 

[spider]

thanx The Godfather have you got any recommendations for wire gauge from there onwards? does everything else look ok.

 

[The Godfather]

thanx The Godfather have you got any recommendations for wire gauge from there onwards? does everything else look ok.

If you install a 50A fuse (13KW), then you are looking at 10mm from this point.

Don & His Boys

 

[spinlondon]

I take it you can't just drill through the wall near the house CU into the garage?

36A for the welder, seems quite a lot. However, I would place that on it's own radial circuit with a 40A type C MCB, and a 63A plug and socket.

 

[Lee321]

a 63A rated 30ma RCD is NOT providing 63a overload protection..

Just 30ma shock protection with the ability to carry and switch off a 63A load without melting or arcing its own switch contacts!

Bit like a main switch rated at 100A, will NOT provided 100A overload protection!

its just capable of switching off a load of 100A without frying your fingers!

well said^ you'd need a rcbo for that