Cable identification between consumer units

[Sparrowhawk]

We have 2 consumer units in the house. After the electricty meter there's a box where the cables split, one to the main consumer unit, and the other via a long white cable (in photo) to the other side of the house.

 

This is a photo of the cable linking the two. I'm trying to estimate the current it can carry before we make alterations. Does this look like 80A cable?

[ProDave]

Can you show a picture of the ends where it splits and where it goes into the consumer unit, and a picture of the consumer unit with the lid off if you are happy doing that.

 

Is there just ONE cable or a pair of near identical cables?

[Alan Ambrose]

One way is to take some calipers and measure the diameter of the copper in one of the main conductors - with the current most decidely off, of course.

 

CSA             Overall Dimensions      Diameter of each Live/  Number of strands       Approx Measurement across             Max
                     Neutral copper core              strand                                                          bundle of strands (‘diameter’)         Current
1mm²            7.8mm x 4.25mm          1.13mm                                   1 (solid core)                                                                       16
1.5mm²          8.2mm x 5mm             1.38mm                                   1 (solid core)                                                                      20
2.5mm²          10.3mm x 6mm           1.78mm                                   1 (solid core)                                                                      27
4mm²            11.9mm x 6.25mm       0.85mm                                  7                               2.56mm                                             37
6mm²            13.5mm x 7mm            1.04mm                                   7                               3.13mm                                             47
10mm²           17.1mm x 10mm           1.35mm                                   7                               4.05mm                                             64
16mm²           19.4mm x 10mm         1.71mm                                    7                               5.12mm                                              85

 

 

It goes without saying that you shouldn't be doing this unless you're completely sure you know what you're doing.

 

Seems possible that its a 64A cable from your picture above.

 

p.s. what's the main 'fuse' rating of the secondary CU?

 

Edited December 13 by Alan Ambrose

[Mattg4321]

Looks like 10mm2 T&E most likely to me. Gut feeling is it’s not 16mm2. 
 

No such thing as 80/64 amp cable. Depends on reference method, type of load,  length of run and de rating factors. 
 

10mm2 is 64 amps in absolute perfect conditions. Unless I could inspect every inch of the run and was happy, I personally wouldn’t be wanting to go over 50 amps OCPD as a rule. 
 

Either way, almost certainly that cable isn’t safely supplying 80 amps to the other end of your house. 

 

Edited December 13 by Mattg4321

[ProDave]

I am still waiting to see how it is fed at the meter end.

[Sparrowhawk]

The washing machine and cooker are still on so I haven't been able to isolate the extension yet, but this is the board at the meter end. "MAIN SWITCH" is the cable running to the extension consumer unit (up the cavity, under loft insulation, down the cavity)

 

Looking in the extension, the cable feeding the consumer unit looks the same size as the one running to the electric cooker. The cooker manual says Total load at 230V is 14.8kW and the previous home owner who installed the cooker has written "(32 amp cut out). Cable? (6 1/2mm sq)" in the manual.

 

[ProDave]

When you are able to turn it off, turn off that main switch and pull out the big fuse to the left of it conveniently hidden behind that post and tell us what rating it is.

 

They only come in 40A, 60A, 80A and 100A.  I HOPE it is a 40A fuse in there, it should be, 60A would only be okay if as already mentioned you knew how the cable was routed for it's entire length.  Voltage drop might also be an issue if it is a long run.