Another summer house question..... or 10

[Tazzy666]

Hi guys, i am after some of your valuable knowledge please.

I am about to erect a summer house and wish to add power.

A few points that i think useful:

1. The summer house is approximately 5m from the garage, which has power. the power is fed in what i believe to be 6mm swa to the house.

2. The house is approximately 75m from the garage.

3. I want 5 double sockets. for minimal usage (phone chargers, small tv, small fridge freezer.

4. I want a 2kW wall heater (no decision as to type yet)

5. 4 lights internally, operated by two switches for two lights each.

6. A couple of outside lights - probably eco bulb type, not floodlights!

Now, i am not an electrician, but have plenty of experience in installation etc, but i want to save as much money as possible. I am more than happy to get it approved and tested professionally, but feel that i can do the bulk myself with a little guidance (your part?) please.

I would love some guidance on the best way to do this. I cannot bury the 5m of cable from the garage to the summerhouse, so it will be on a raised post and rail between the two, specifically for the cable.

the garage is feeding a socket and a light internally. Some outside lights in the garden which i believe to be 4mm swa are also fed from the garage.

I want this to be professionally signed off at the end of it, but the calcs etc for what i need to do for the new, and maybe upgrade to the old is the main issue for me.

Final q, is it nessary to be a ring main in a single room? can i run one way round the room from the main board and also then run the other? if that makes sense.

oh, i should say, that i want to run the power from the garage rather than a new feed back to the house


Thanks all for your time in advance.

Keith

Incoming supply

Incoming earth

Main board in house

Garage board

 

[Heinz57]

Hello there,

Your main consumer unit board. You say this is located in your house? Do you think you would beable to take the feed from there?

Here is how I would do it....

Take a new feed from the consumer unit using 2.5mm cable, with a 30A MCB. Alternativly, you might beable to put a new smaller consumer unit (consisting of the above) next to the unit in your garage*

The circuit will also require high sensitivity RCD protection

Inside the summer house have a smaller consumer unit with a main isolating switch and two MCBs, the first rated at 30Ma for the plug socket outlets. The second rates at 5A for the lighting circuit.

You can do the plug socket circuit in whichever way you like, ring or radial circuit.

Alternativly, you can miss out the consumer unit in the summer house by doing the following...

Take a 30A MCB feed, from the house or garage. And use this for your plug socket circuit as normal. You can then feed the lighting by taking spurs from these plug sockets via an FCU rated at 5A (Switched or unswitched. I'd go switched because then it will enable you to isolate only the lighting circuit but still use the plug sockets should you need to)

As far as I know, the earth connection from the summer house's circuit can't connect to that of the main circuit. Instead, connect up an earth rod driven into the ground*

*Can someone clarify these for me please?

Hope I've helped,

Heinz

EDIT - Forgot about the heater! I belive you could power this by taking a spur via an FCU (Unsure of what rating) from one of the socket outlets

EDIT 2 - That sould be A not mA!

 

[TheGayOwl]

Don't take this the wrong way...

You may well find it very very hard to get a spark to certify your install. Some of that gear should be in a museum!

If you have a 80m garden surely you can shell out to get it done properly. presumptuous on my part I know!

There are many things for you to consider on this installation. Get a professional in.

 

[TheGayOwl]

Here is how I would do it....

Take a new feed from the consumer unit using 2.5mm cable, with a 30mA MCB

Heinz you surely mean 30A (or 32A).. Could not power much off 30mA!

 

[1john]

Hello there,

Your main consumer unit board. You say this is located in your house? Do you think you would beable to take the feed from there?

Here is how I would do it....

Take a new feed from the consumer unit using 2.5mm cable, with a 30mA MCB. Alternativly, you might beable to put a new smaller consumer unit (consisting of the above) next to the unit in your garage*

The circuit will also require high sensitivity RCD protection

Inside the summer house have a smaller consumer unit with a main isolating switch and two MCBs, the first rated at 30Ma for the plug socket outlets. The second rates at 5Ma for the lighting circuit.

You can do the plug socket circuit in whichever way you like, ring or radial circuit.

Alternativly, you can miss out the consumer unit in the summer house by doing the following...

Take a 30mA MCB feed, from the house or garage. And use this for your plug socket circuit as normal. You can then feed the lighting by taking spurs from these plug sockets via an FCU rated at 5A (Switched or unswitched. I'd go switched because then it will enable you to isolate only the lighting circuit but still use the plug sockets should you need to)

As far as I know, the earth connection from the summer house's circuit can't connect to that of the main circuit. Instead, connect up an earth rod driven into the ground*

*Can someone clarify these for me please?

Hope I've helped,

Heinz

EDIT - Forgot about the heater! I belive you could power this by taking a spur via an FCU (Unsure of what rating) from one of the socket outlets

So this is what they mean by the blind leading the blind!!

You need to get a sparky on side for this work before you start anything, they will need to make the design descisions, not us as we are not going to be signing it off for you.

Do you plan on having a water supply?

Have you enquired with the DNO if there is a possibility of having a PME upgrade?

 

[Heinz57]

Here is how I would do it....

Take a new feed from the consumer unit using 2.5mm cable, with a 30mA MCB

Heinz you surely mean 30A (or 32A).. Could not power much off 30mA!

Yep I do. My mistake. Sorry its late. Ill correct them


To the OP - As the others have pointed out, talk to the sparky and seek some more advice from them before carrying out the works. Also the unit in your garage does look quite old. I would recomend having that replaced with something new and modern while your at it

 

[TheGayOwl]

Thats exactly what I thought!

 

[Tazzy666]

thanks heinz, i will be seeking professional expertise addtionally to this.

the main consumer unit is in the house and running a new feed would be quite costly and inpractical for me.

the alternative may be an option - and one i had not thought of.

yes, i think the complete garage is due for an overhaul!


gayowl - i have taken it the wrong way! yes i may find it hard to get a spark to certify - but that is a consideration. yes some of the gear should be in a musuem - but we cannot all afford to upgrade to the latest equipment etc as things progress. I really don't think having an 80m garden means i can afford to get it done properly. I intend to to get the work done properly, but there is also work i can do like running cables etc - to keep costs down of a professional, but yes - i agree there are many things to consider.

1john - no water. no i have not enquired

 

[1john]

Hello there,

Your main consumer unit board. You say this is located in your house? Do you think you would beable to take the feed from there?

Here is how I would do it....

Take a new feed from the consumer unit using 2.5mm cable, with a 30A MCB. Alternativly, you might beable to put a new smaller consumer unit (consisting of the above) next to the unit in your garage*

The circuit will also require high sensitivity RCD protection

What type of cable are you suggesting?
Are you sure that 2,5mm cable is suitable to be fused at 30A?
Can you duplicate you calculations for volt drop on an 80m run?

Inside the summer house have a smaller consumer unit with a main isolating switch and two MCBs, the first rated at 30Ma for the plug socket outlets. The second rates at 5A for the lighting circuit.

Is it acceptable to apply no diversity between fuses?

You can do the plug socket circuit in whichever way you like, ring or radial circuit.

What size cables would you reccomend with your stated 30A OCPD ?

 

[ricicle]

Hello there,

Your main consumer unit board. You say this is located in your house? Do you think you would beable to take the feed from there?

Here is how I would do it....

Take a new feed from the consumer unit using 2.5mm cable, with a 30A MCB. Alternativly, you might beable to put a new smaller consumer unit (consisting of the above) next to the unit in your garage*

The circuit will also require high sensitivity RCD protection

Inside the summer house have a smaller consumer unit with a main isolating switch and two MCBs, the first rated at 30Ma for the plug socket outlets. The second rates at 5A for the lighting circuit.

You can do the plug socket circuit in whichever way you like, ring or radial circuit.

Alternativly, you can miss out the consumer unit in the summer house by doing the following...

Take a 30A MCB feed, from the house or garage. And use this for your plug socket circuit as normal. You can then feed the lighting by taking spurs from these plug sockets via an FCU rated at 5A (Switched or unswitched. I'd go switched because then it will enable you to isolate only the lighting circuit but still use the plug sockets should you need to)

As far as I know, the earth connection from the summer house's circuit can't connect to that of the main circuit. Instead, connect up an earth rod driven into the ground*

*Can someone clarify these for me please?

Hope I've helped,

Heinz

EDIT - Forgot about the heater! I belive you could power this by taking a spur via an FCU (Unsure of what rating) from one of the socket outlets

EDIT 2 - That sould be A not mA!

I suggest you stop posting advice on here until you have grasped proper electrical design principles.

 

[ban-all-sheds]

gayowl - i have taken it the wrong way! yes i may find it hard to get a spark to certify

Impossible if you just present a fait accompli.

yes some of the gear should be in a musuem - but we cannot all afford to upgrade to the latest equipment etc as things progress.

I know it has a red test button, not a yellow one, but there is an earth connection to the device after the meter - if it's a Voltage Operated Earth Leakage Circuit Breaker it needs replacing because it's unreliable and not providing the protection you need, not just because it's old.

And talking of earth, yours appears to be a bit of 15mm plumbing pipe rather than a proper electrode.

a) It might be dodgy.

b) It makes me wonder what other "innovative" bodges might have been done by the same bodger elsewhere in your house.

I intend to to get the work done properly, but there is also work i can do like running cables etc - to keep costs down of a professional,

Only with their agreement up-front, and with you doing what they direct.

 

[Heinz57]

What type of cable are you suggesting?
Are you sure that 2,5mm cable is suitable to be fused at 30A?
Can you duplicate you calculations for volt drop on an 80m run?

Correct, yes the voltage drop should be taken into account, which may well increase the cable size. Hands up, I may have got that one wrong. After doing some re-calculations, if a 5% voltage drop is taken into account, then a cable of at least 10 mm² would probably be required, a 3% voltage drop then it would be up to 25 mm²

Is it acceptable to apply no diversity between fuses?

Ring mains are usualy fused at 30 - 32A, lighting circuits at 5 - 6A

What size cables would you reccomend with your stated 30A OCPD ?

Well its a summer house, floor space won't be gigantic, there probably won't be too many sockets required in the circuit. I'd say 2.5mm², even better would be going up to 4mm²

 

[1john]

I think you should not advise, by your own admission you have specced a cable for someone that is a quater of the csa that it should be. It is very unlikely that you will find a "ring main" circuit in a domestic setting. You are happy to put an equal size OCPD some 80 meters away from the installation that is to feed a socket circuit which you have reccomended to be of the same saze with an additional lighting load on it, in fairness the likelyhood of the socket circuit drawing 30A is low, it is still bad practice.

 

[ban-all-sheds]

even better would be going up to 4mm²

Why?

 

[Bodgeitandleggit]

Tazzy, I am not a electrician but I asked a similiar question on another forum as I was putting in the SWA myself and although the calculations for the voltage drop I needed 4mm , one piece of advice was to future proof it in case of any heavy loads at a later date, so I ended up with a 10mm SWA ...over the top I know but it will not require re-doing if i do add anything