Consumer Unit Change

[Nickj]

Hi All,

I am tomorrow going to be changing a consumer unit ahead of my Elecsa assessment next week.

Just wanted to check that I'm not missing anything with regards to amendment 3.

I'm going to be using a BG consumer unit supplied with RCBOs.

It has a cut out at back for cable entry and so I am going to pass all cables through that using a grommet strip around the metal edges. Do I need to seal the entry hole? I believe not however I have heard arguments that it needs to be sealed. Passing all cables through the rear entry may require de-rating cables due to grouping however the cables enter the current board (3036's) through the rear. Can i therefore assume ratings are fine?

I am going to attach the consumer unit to the wall using dewalt wall dogs which require no anchor in wall meaning I don't have to worry about plastic wall plugs falling out in the event of a fire.


If the cables are too short (I sincerely hope they won't be) I'll use an adaptable box above the board to mount a din rail to extend wiring. Does this adaptable box need to be non-combustible too? (associated switch gear covers this possibly?)

Thanks in advance

Nick

 

[tony mc]

I know faults can be a real pain to find especially when you have been looking for some time!
You say the fault is the last leg or first leg to a S/O from the CU and a CPC fault.
I would be inclined to join L/N at one end and take a reading just to see if the maths matches up with the distance to the CU just in case its a way out reading and the cables run goes elswhere.
Just my opinion as I have come across strange cables runs with no logic in the past!

Good luck with your assessment!

 

[westward10]

I love fault finding, it is the bit before I find the fault which is an ---.

 

[Nickj]

Ok so decided to lift floorboards to satisfy my curiosity. Cable went to an unused and totally forgotten about socket in a cupboard in the hall!

There was a loose connection in that. tightened up and I'm now getting 0.95- 1 ohm.

One would expect it to be 0.7 ohms or so.

My question is, would you continue fault finding to find where the last 0.3 ish ohms are coming from or would you (and my assesssor) agree that as it's close to expected value it's fine?

 

[Octopus]

I would remove the "last" socket and test the Zs on each leg of the ring to see what the readings are like - then consider the options......

 

[Midwest]

The purists will argue you should. But you will have to round to each connection, undo & re-terminate. Your first assessment, your choice. Of course you could argue what you have done thus far has improved the installation, and you determination to locate the fault, might impress your inspector. Perhaps try the former, but you will need to draw the line somewhere, think your Zs' was good?

 

[westward10]

Are they definitely 1.5 cpcs and not 1.0.

 

[Midwest]

Wonder if OP reconnected old socket (faulty leg). Perhaps temporarily remove socket and replace with strip connectors or similar. Good point re the cpc sizes Westward though.

 

[Midwest]

Could even be imperial sized cable, bit before my time, cough, so don't know how they compare L/N to cpc?

 

[westward10]

Could even be imperial sized cable, bit before my time, cough, so don't know how they compare L/N to cpc?

I think the cpc on imperial size cables weren't much different to the line size.

 

[Pete999]

Could even be imperial sized cable, bit before my time, cough, so don't know how they compare L/N to cpc?

7/029 Live =3/036 cpc I think will look for a comparison chart when the vino has worn off.

 

[tony mc]

He said the cables were solid as he was asking for extending advice and imperial are stranded and better cables IMO!
Could be older 2.5 T/E with 1mm CPC!

 

[sparksburnout]

7/029 Live =3/036 cpc I think will look for a comparison chart when the vino has worn off.

Pierre or you on the **ss every evening?

 

[Pete999]

Pierre or you on the **ss every evening?

Thursday off

 

[Pete999]

Pierre or you on the **ss every evening?

Not on the ----, just like the odd glass, nothing serious, it's just people's take on my posts, aint really been on the razz for many a year or two, had my fill of that during my world tour, red wine is my tipple, now I'm retired, but er in doors has got me on a shed building course for OAPs, of course I will be asking advice on how to run a supply to the sheds I build. LOL

 

[DPG]

Make sure you TT it. Wooden shed, so got to be a wooden earth spike. No, hold on a minute - that wooden work. OK, I'll get me coat. Daz