New 4 way CU being fed from 50A MCB on old CU

[alPudsey]

HI, I ve briefly asked about this setup before but now asking about the load on 4 way...... is this Ok/Safe ?

I have a plastic 10 way CU.....one of the 50A MCBs from this has been used to feed the new 4 WAY metal CU.
The new 4 way METAL CU has an 80A main switch (30Ma) and 4 MCB's (50a,32a,32a 6a)

With 4 way metal CU being fed from a 50A MCB from the plastic 10 way CU, is it safe to have a 50A shower and 2x32A ring mains and a lighting circuit running on the 4 way ...all being fed from a 50A MCB ????

 

[James]

It may well be ok, but could also be overloaded.
it depends on the loads attached to the circuit breakers.

do you have an installation certificate?

 

[HappyHippyDad]

It may be ok, but may well not be ok.
The shower is probably a 10.5kW if it is on a 50A, therefore using 47A. That really doesn't leave much for 2 rings before the up front 50A (in the main CU) either trips, or is perhaps at full capacity or over during every shower taken.
As James says, it would be good to see the installation certificate, otherwise we are guessing.

 

[Vortigern]

I think you have to check the circuit design from the main DB, and then the sub main. I suspect the existing cabling, unless this has been thought through properly in the first installation of the sub main, would not comply with BS7671 due to cable being inadequate for the proposed loads, taking into account maximum demand for each CU. Bit confused you show a picture of the four way presumably, what MCB supplies this from the 10 Way. Is this to an annex?

 

[alPudsey]

It may well be ok, but could also be overloaded.
it depends on the loads attached to the circuit breakers.

do you have an installation certificate?

I'm awaiting certificate. I'm.guessing that certificate values will alert you qualified chaps if it's a good setup or not.. will post it once received. I ask as the electrician didn't seem to doany tests. Didn't even take his leads out for his device( wasn't a fluke.or megger but similar). Just toolanim unit into dormers and came.back down 10/15ims later. I know he never took any light fitting/bulbs off or removed ring mains socket faces or light switch fronts (as I'd sealed edges with caulk etc week before ). Still as I'd led them. No idea what tests he thinks he's done. He Only did one test at CU and that was. Z read . Anyway, I'll see what his report shows and post it here

 

[alPudsey]

It may well be ok, but could also be overloaded.
it depends on the loads attached to the circuit breakers.

do you have an installation certificate?

No CERT as yes but expecting.it anytime. I'm assuming the values/figures on there will tell you qualified peeps, if it's a good setup.or not?? Will post photo as soon as I get it.
Tbh , I have little faith in the electrician and I saw little or near zero tests being done... No socket or switch faces taken off, no bulbs removed for resistance tests? No joining of earth to live and so on(R1+R2?? ) as Googled prior.to his attendance. Was expecting to see some of the tests seen in video but only a read at CU (Z read I think they call it). Anyway, will post cert here once received

 

[alPudsey]

It may be ok, but may well not be ok.
The shower is probably a 10.5kW if it is on a 50A, therefore using 47A. That really doesn't leave much for 2 rings before the up front 50A (in the main CU) either trips, or is perhaps at full capacity or over during every shower taken.
As James says, it would be good to see the installation certificate, otherwise we are guessing.

Will.post certificate on here, once received. Thx