EICR failure site - righting the wrongs

This is a follow-up video to an EICR we performed back in March 2019 where the electrical installation had exceeded the capacity of the RCD on site resulting in its mechanical failure.

Original video:    • EICR FAIL- Maximum demand  

The demand problem has been reduced in the following ways:
One of the three electric showers has already been decommissioned.
A second electric shower is to be decommissioned and a new one is to be installed from one of the two gas boilers.
Three of the socket circuits have been reduced to 20A.

New maximum demand calculations/measurements:
Circuit 1: Shower: 7500W 32A
Circuit 2: Shower: 7500W 32A
Circuit 3: Cooker: 4600W: 10A + 30% of remainder = 13A [diversity calculation]
Circuit 4: Cooker: 4800W: 10A + 30% of remainder = 13.27A [diversity calculation]
Circuit 5: Socket ring: 32A [no diversity]
Circuit 6: Socket ring: 12.8A [40% diversity]
Circuit 7: Socket radial: 8A [40% diversity]
Circuit 8: Socket radial: 8A [40% diversity]
Circuit 9: Socket radial: 8A [40% diversity]
Circuit 10: Socket radial: 8A [40% diversity]
Circuit 11: Shed [DB2]: 16A
Circuit 12: Water heater: 13A
Circuit 13: Lighting: 1.6A [Actual]
Circuit 14: Lighting: 0.3A [Actual]
Circuit 15: Lighting: 0.25A [Actual]
Circuit 16: Lighting: 0.5A [Actual]
Circuit 17: Lighting: 0.6A [Actual]
Circuit 18: Doorbell/lighting: 0.05A [Actual]
Circuit 19: Lighting: 0.7A [Actual]

Adding this lot up gives a new maximum demand on paper of about 200A which is twice what the main fuse is rated for. But then, this is why the maximum demand calculation is a bit of a nonsense. Those socket circuits aren’t really going to be pulling 76.8A at any given time on any given day, the shed isn’t likely to be pulling 16A, the water heater is only used when the combi boiler breaks down, etc. The problem before was three electric showers plus all the socket outlets hanging off a single 63A RCD, but now that everything has been split out there is no single point at the CU which is being exposed to more current than it is rated for.

A few additional notes not covered on camera to fend off some of the questions likely to be asked in the comments….

I would have preferred to terminate the SWA directly onto the metal CU enclosure, but the knockout on the right side of the board is 32mm. Had there been a 20mm knockout, I would have done this, but I didn’t want to holesaw one in, so I went for the quicker and easier option of terminating it onto a Wiska box with a bit of T&E then going to the board. A Wiska locking nut makes for an easy way to terminate the sheath.

As shown, CP Fusebox have said on Twitter that their Type-A small form factor RCBO’s should be out around October 2019 and should have longer neutral flyleads.

Many circuits required extending, some of which were in junction enclosures, others were extended in the box trunking using Wago connectors. This work took place a while ago, it’s just taken me some time to get organised enough to edit it together and some footage was lost, so apologies that there are one or two things not shown here.

Some people are very neat with their cable forming in consumer units, but this job took all day, and this is neat enough as far as I’m concerned. I also see some people cable tie the wires to keep them together which is a no-no as it brings grouping factors into play. For more on that, I refer you to this excellent video from SparkyNinja:
   • Cable Grouping and the impact on elec...  

A couple of pedants commented on the previous video that “FAIL” was the wrong term for an EICR and I shouldn’t have described it that way. Well, the installation FAILED to meet the criteria required by the reporting process for a ‘satisfactory’ outcome. So bore off.

Links:
CP Fusebox gear was sourced from Gil-Lec Electrical:
https://www.gil-lec.co.uk/circuit-pro...

Haste UK: http://www.hasteltd.co.uk/

YouTube channels showing CU installations and discussing Type-A RCD/RCBO’s:
CJR Electrical:
   / @cjrelectrical  
DSS Electrical:
   / Канал  
Artisan Electrics:
   / @artisanelectrics  
e5 Group:
   / @e5group  
…and may I also ask you to check out J Beck Electrical ‘cos I like the way his dick swings:
   / @jbe  

Affiliate links:
Wiska earth locking nuts: https://amzn.to/2YP1HqJ
Wagobox enclosures: https://amzn.to/2YGbnU1
Wago connectors: https://amzn.to/2YBNxEZ
Brother label printer: https://amzn.to/318Lbzc