Electrician Jobs Installing a secondary consumer unit in the garage??

[TheDoctor]

Morning all,


I am looking to install a secondary consumer unit in my garage, linking from my existing house consumer unit.


The first question is If it is ok to run 16mm2 Twin and earth SWA through my hallway and lounge concrete floor in order to get to the garage or should I be running it through the walls? I intend to run a 60A supply to the garage. I could run conduit in the concrete floor?


Secondly, would it suffice to add a 60A rated RCD to the existing house consumer unit for the SWA to run to the garage. The garage consumer unit would then just have a mains switch and MCBs for each circuit.


I intend to run a ring main for sockets all round the garage, a radial for three florescent lights and potential a radial high amp outlet for a welder.

 

[telectrix]

firstly, the SWA itself does notneed RCD protection unless the house is TT earthing. better to fit RCD in garage, then a fault in the garage will trip in the garage, not the house. Secondly, should be no problem burying SWA in concrete floor, but I'd duct it.
you could fit a 63A MCB (house end, non-RCD), then sub-board in garage with RCD and appropriate MCBs.

 

[Deleted account]

If your running twin and earth you will need rcd protection if depth of cable is less than 50mm deep in walls and floors. There are a few other criteria too you would need rcd protection for. Also you need to know the correct zones for running the cable.

However you don't need rcd protection of the supply cable if your running it in SWA.

Peter

Edit: Bugger beat me to it tel

 

[TheDoctor]

Thank you for your prompt responses.


Can I ask what sort of ducting would be ideal to run the SWA in and why I need the ducting if its SWA?


Do I need RCD protection if I am less than 50mm but in SWA?


In terms of zoning I am struggling to find info as most diagrams show wall and ceiling wiring zones. I am simply going through the hall and lounge floor to the outside.


My house is a new ish one using TN-C-S earthing


Regards,

 

[Octopus]

May be you should get a local spark involved and if you are in England or Wales this work falls under part p

 

[telectrix]

ducting protects the SWA from any possible reaction with the concrete, and also gives it that extra protection from mechanical damage to the sheath. any 2" or thereabouts plastic duct will do. zoning applies mainly to cables buried in walls. there's a perfect diagram in OSG.

 

[TheDoctor]

Thanks,

Whats everyone thoughts on running twin and earth through insulation. Does it just need up-rating for heat dissipation? or should it be run through conduit?

 

[TheDoctor]

Can I also ask that if I pay a sparky to install a ring with a few sockets and a few lights. Can I add to the ring and lights without notifying the authorities?

 

[Octopus]

Said spark needs to do the sub main and the initial circuits ....
After that it's possible for you too make changes to said circuit.

What do you plan to use in the garage?

 

[telectrix]

Said spark needs to do the sub main and the initial circuits ....
After that it's possible for you too make changes to said circuit.

What do you plan to use in the garage?

think basic sockets and lights initially, but he stated he was planning on getting a welder. the load of the welder need to be considered before designing the installation.

 

[Octopus]

^^ hence my closing sentence .....

 

[TheDoctor]

I am an engineer by profession and have a welder, lathe and mill. I need a sub main, socket outlets and lights. Potentially a higher rated fused outlet for a welder. If i were to add more sockets or lights I would hope its something I can do without need it signed off again? As long as I am not adding another circuit to the sub main?

I assume in the garage I can just run the twin and earth clipped straight to the single leaf wall or through conduit?

 

[TheDoctor]

The welder will be pulling 45 Amps, just checked and the power is 11kw

 

[Strima]

What rating is the DNO fuse?

 

[TheDoctor]

I have a 100amp supply so assume 100Amp

 

[davesparks]

I am an engineer by profession and have a welder, lathe and mill. I need a sub main, socket outlets and lights. Potentially a higher rated fused outlet for a welder. If i were to add more sockets or lights I would hope its something I can do without need it signed off again? As long as I am not adding another circuit to the sub main?

I assume in the garage I can just run the twin and earth clipped straight to the single leaf wall or through conduit?

All electrical work should be carried out in accordance with BS7671, this includes inspection, testing and certification of the work. Notification for the purpose of part P however wouldn't be required for the extension of the circuits if not in a special location.

Clipped direct cables would not be appropriate to the workshop kind of environment, I think the most suitable option would be steel conduit due to the risk of damage to the cables from weld spatter, metal chips and general moving of materials and heavy tools.

 

[David M]

The welder will be pulling 45 Amps, just checked and the power is 11kw

I assume this is an arc welder? It will most likely require hard wiring into an appropriate rated isolator. During use of the welder you may notice a voltage drop which will cause lights to annoyingly flicker. Long continued use will cost you dearly in your electricity bills. (just some friendly advice)
From experience, if you intend to use this as a "professional" workshop then be aware that the council/authorities may get involved and you will require planning permission.

 

[Loki]

Hi,

Where did you get that 100 Amp from?
If it was on the dno's main fuse housing then the fuse inside could be less.
As your not ment/allowed to pull the main fuse "but people do i know lol" you would need to call you supplier & confirm this.

Michael

 

[Loki]

Deleted double posted for some reason

 

[TheDoctor]

Hi,

Where did you get that 100 Amp from?
If it was on the dno's main fuse housing then the fuse inside could be less.
As your not ment/allowed to pull the main fuse "but people do i know lol" you would need to call you supplier & confirm this.

Michael

Why do I need to know this?

 

[Octopus]

^^ very simply if it's a 60a then the combined load of the house and garage could easily blow out.

Me thinks you need to consult a decent local spark.

Where are you based?

 

[FatAlan]

Sounds like a good workshop. You're not Colin Furze by any chance?

 

[TheDoctor]

^^ very simply if it's a 60a then the combined load of the house and garage could easily blow out.

Me thinks you need to consult a decent local spark.

Where are you based?

Ah I see. Well I was applying the rules of diversity and the fact I dont have one electric shower or similar in the house so the welder basically pulls a similar current. My showers and rads are all gas. The 100amps came from the fuse located near the meter and the main switch in the consumer unit.

 

[TheDoctor]

Sounds like a good workshop. You're not Colin Furze by any chance?

I can only dream! Well its my first house and the garage is big enough for a decent workshop. I am employed full time so main use will be home projects.

 

[Octopus]

100 a on a main switch is normal and 100 a on a fuse carrier gives the max rating so nothing can be assumed...

 

[TheDoctor]

100 a on a main switch is normal and 100 a on a fuse carrier gives the max rating do nothing can be assumed...

I see. well my current housing circuit has two 80 amp RCD's

 

[Pete999]

Why do I need to know this?

Thought "The Doctor" knew everything, are you sure this isn't a neww bit of kit you're installing in the "Tardis" if you're doing it yourself make sure you torque the connections with you Sonic screwdriver.

 

[Octopus]

I see. well my current housing circuit has two 80 amp RCD's

Which also means nothing helpful

 

[TheDoctor]

Which also means nothing helpful

How can I find out the actual rating?

 

[Midwest]

How can I find out the actual rating?

For the main fuse #18

 

[TheDoctor]

so how much is it going to set me back to get a sub main installed in the garage with 1 32 ring and a lighting radial? roughly speaking. Assume the swa channel is already chased.

 

[Pete999]

so how much is it going to set me back to get a sub main installed in the garage with 1 32 ring and a lighting radial? roughly speaking. Assume the swa channel is already chased.

Get an Electrician in ti give you a quote, simples.

 

[davesparks]

so how much is it going to set me back to get a sub main installed in the garage with 1 32 ring and a lighting radial? roughly speaking. Assume the swa channel is already chased.

Roughly speaking somewhere between £500 and £5000.

Or in other words how on earth can anyone give a price without actually knowing what they are pricing for?

 

[Midwest]

A little harsh davesparks the OP is only asking. OP, the only real way in any case, to get this work done is by a qualified competent electrician, its a bit more than putting up some lights you've got from B&Q. Think Pete suggestion is the way to go.

PS your electrician might suggest you doing some labour work, like trench/chasing for your supply cable, which may save you some pounds.

 

[davesparks]

A little harsh davesparks the OP is only asking.

And I'm only answering, do you think the price won't be somewhere between those two,figures?

 

[Midwest]

And I'm only answering, do you think the price won't be somewhere between those two,figures?

Would you speak to your potential customers like that?

 

[telectrix]

what's the point of ------footing around. davesparks is right. nobody can give a more accurate estimate without physically seeing the job and pricing up equipment and estimating a timescale.

 

[Midwest]

what's the point of ------footing around. davesparks is right. nobody can give a more accurate estimate without physically seeing the job and pricing up equipment and estimating a timescale.

It was actually quite mild reply from davesparks, but I kinda sensed the next few wouldn't be. Anyway, whichever your viewpoint the OP seems to have taken on-board the advice

 

[Thunderbird2]

HI
I am aiming to install a garage CU that extends a circuit between the main CU to a new garage CU. The new garage CU will be used on three circuits
a) I have run 50m of 6mm 3 core SWA between the garage and shed A. This is to feed a couple of sheds that will both have lights and sockets. I am to install a garage CU with 30mA RCD in each shed to run the light cicrcuit and sockets. Shed A will also serve a 32a circuit for shed B
b) seperate 2.5mm SWA on 6a circuit to run 6/7 LED lights in the garden. Will run off the new garage CU
c) seperate 2.5mm SWA on 20a circuit to run a water feathure in the garden

Now my question is it ok to have
Main CU connected to garage CU with 6mm SWA cable (this Tenby unit has dual RCD and non RCD). The new garage CU will have RCD protection
a new garage CU is installed in shed A and also has RCD protection
finally another garage CU Is installed in shed B that also has RCD protection

All because I cannot find an adequate garage CU that does not have RCD protection

 

[UKPN]

Thank you for your prompt responses.


Can I ask what sort of ducting would be ideal to run the SWA in and why I need the ducting if its SWA?


Do I need RCD protection if I am less than 50mm but in SWA?


In terms of zoning I am struggling to find info as most diagrams show wall and ceiling wiring zones. I am simply going through the hall and lounge floor to the outside.


My house is a new ish one using TN-C-S earthing


Regards,

Dont forget if you are running 16mm T and E the earth will be too small. 10mm earth required.

 

[Strima]

Dont forget if you are running 16mm T and E the earth will be too small. 10mm earth required.

That's only if there's a requirement to bond services back to the MET, if there's no bonding requirement then the earth is sized accordingly depending upon the result of the adiabatic equation.

 

[Strima]

HI
I am aiming to install a garage CU that extends a circuit between the main CU to a new garage CU. The new garage CU will be used on three circuits
a) I have run 50m of 6mm 3 core SWA between the garage and shed A. This is to feed a couple of sheds that will both have lights and sockets. I am to install a garage CU with 30mA RCD in each shed to run the light cicrcuit and sockets. Shed A will also serve a 32a circuit for shed B
b) seperate 2.5mm SWA on 6a circuit to run 6/7 LED lights in the garden. Will run off the new garage CU
c) seperate 2.5mm SWA on 20a circuit to run a water feathure in the garden

Now my question is it ok to have
Main CU connected to garage CU with 6mm SWA cable (this Tenby unit has dual RCD and non RCD). The new garage CU will have RCD protection
a new garage CU is installed in shed A and also has RCD protection
finally another garage CU Is installed in shed B that also has RCD protection

All because I cannot find an adequate garage CU that does not have RCD protection

In bold, depending upon your intended load for the garage and sheds 6mm SWA on a 50m run is not suitable for voltage drop requirements. Depending upon the loads and distances for the next two sheds you'd be looking at either 10 or 16mm to supply the garage.

Also depending upon load and distance you could possibly use 1.5mm SWA for the lights and water feature.

All of the above is also reliant upon installation method, i.e. buried/clipped to a wall etc.

I would urge you to consult a local electrician to have this designed correctly and depending upon your location there's also Part P notification to be considered.

 

[Timbo]

Dont forget if you are running 16mm T and E the earth will be too small. 10mm earth required.

Dont forget if you are running 16mm T and E the earth will be too small. 10mm earth required.

I'm sure he got it done before this, it was 3 years ago!