Wiring a consumer Unit

[Daveled]

I have just installed a "CUGAR1" garage unit in my shed. It consists of a 40amp RCD, a 6 amp MCB and a 16 amp MCB.

I brought the incoming power from the house on a 2.5 mm twin and earth. I have wired the live into the RCD (it already had a neutral cable going to the neutral bar), fitted the busbar between the live point of the RCD and both of the MCB's.

I have wired a striplight to the 6 amp and a ring main of 13 amp sockets to the 16 amp MCB.

When I turn the light on it trips the main switch and when I plug something into any of the sockets its OK until I try to use it then it trips the MCB.

Can anyone tell me what I have done wrong please.

Thanks

 

[Iggifer]

Did you put the neutral from the T+E into the RCD? if not that's your problem

did you put the T+E into the top of the RCD? And matched up the L+N with the cables/bar at the bottom?

And you have the neutrals in the (correct) neutral bar and earths in the earth bar?

 

[securespark]

Need a picky of how you've wired it up!

We like pictures!

 

[Daveled]

I put the neutral into the cables bar at the top because there is already a heavy neutral cable coming from the RCD into the cables bar.

The Earth of all cables is going into the cables bar and the live into the MCB.

Is this wrong?

 

[Daveled]

Need a picky of how you've wired it up!

We like pictures!

Will do but I cant get one til the morning (no light)

 

[riveralt]

I brought the incoming power from the house on a 2.5 mm twin and earth. I have wired the live into the RCD (it already had a neutral cable going to the neutral bar), fitted the busbar between the live point of the RCD and both of the MCB's.

Where did you wire the incoming Neutral?
The neutral from the RCD will leave the bottom of the unit to the neutral bar the incoming neutral should go in the top.
Doesn't sound as if their is a neutral across the RCD.
What about your earth?

 

[riveralt]

I put the neutral into the cables bar at the top because there is already a heavy neutral cable coming from the RCD into the cables bar.

Therefore bypassing the RCD

 

[Daveled]

I brought the incoming power from the house on a 2.5 mm twin and earth. I have wired the live into the RCD (it already had a neutral cable going to the neutral bar), fitted the busbar between the live point of the RCD and both of the MCB's.

Where did you wire the incoming Neutral?
The neutral from the RCD will leave the bottom of the unit to the neutral bar the incoming neutral should go in the top.
Doesn't sound as if their is a neutral across the RCD.
What about your earth?

As soon as it gets light in the morning I will take the incoming neutral out of the neutral bar and put it into the top of the RCD.

Thank you very much for your help it is really appreciated.

Dave

 

[xr4x4]

What's the 2.5 t&e connected to at the other end?

 

[ban-all-sheds]

Better still - as soon as it gets light enough for you to read the phone book, call an electrician.

You have made such a fundamental error in wiring this CU that it is evident that you don't know what you are doing - what made you think that you did?

Did you apply for Building Regulations approval? If so, what did you say would be the way that you'd ensure that your work complied with Part P?

You used twin & earth to supply the shed - how/where does it run, and how is it mechanically protected?

Is it on an RCD? If so, what's the point of another one in the shed? If not, is it concealed in a wall or partition anywhere?

What size breaker is it on? Will you get discrimination with the 16A one in the shed?

How long is the cable? Have you checked that volt-drop and fault loop impedance are OK?

What about testing? Do you know what tests you would carry out on the sub-main, the CU, and the final circuits - what sequence you'd do them in and at what point you would energise it all? For each test do you know what is being measured, why it is important, how you would carry out the test, and with what equipment, and what sort of results you would expect to get if everything was OK?

 

[Daveled]

To everybody who replied to this post, it is now resolved. Thank you very much for your input it was appreciated.

Thanks again

Dave

 

[ban-all-sheds]

What's resolved?

Building Regulations approval?

Proper installation of twin & earth to supply the shed?

Proper discrimination between RCDs & MCBs?

Volt-drop and fault loop impedance calculations?

Testing? You did all of the dead and live tests properly, and everything was OK? You have a schedule of test results you can scan in and post here?


Or are you of the mindset that "if the lights stay on then everything must be OK", and you aren't going to take any notice of anything which says there's a lot more to it than that?

 

[securespark]

You've scared him away.