New Comer requires a little advice on an unusual Mains Supply to the local pub.. HELP

[Red Spot]

Hi, I m very new to this so please go easy...

Got called out to the local pub yesterday to a supply fault, the Landlord has informed me that every now again (usually a Saturday night when they are busy) the pub will loose all power. The Supplier is called out and usually replace the Fuse next to the Transformer (the pub is out in the sticks, transformer probably about 50m away) The supply cable itself has burned out and been replaced twice already, Supplier says they are drawing too much current.

Clamp tested the incoming and found at the time it was drawing around 135Amps, now the fun bit! The incoming cable goes into the 100Amp main fuse, then has a split from the supply side into another 100Amp main fuse (2 x 100Amp main fuses being fed from one supply, single phase)

One Fuse then supplies one meter and the other a second Smart meter, both meters then go down to feed a Square D 3 pole 125Amp Main Switch, the third pole is linked to the first pole on the switch as its a three phase board (single phase supply)

All the circuits fed from this DB appear fine and are drawing as a total around 20Amps (lighting, sockets, Fire alarm etc) There is however a Three Pole Square D KQ 10C363 63Amp MCB feeding a five core 16mm SWA which supplies DB2 in the kitchen, this is drawing around 95AMps (split between the three poles, other two cores are Neutral and earth)

Checked the regs for a start and the 16mm multi-core SWA is rated (clipped direct which it is not) @ 77Amps (it is fed through the wall and i would guess through the ceiling void ground floor.

I m guessing the supply is only 100Amps as it keeps melting the supply cable to the pub and taking the supplies fuse by the transformer, so why on earth does it feed 2 x 100Amp main fuses, each would then require a current of over 100Amps to blow, therefore they are providing no protection to the building supply.

I v got some pictures but cant upload them yet, any advice on the above would be greatly appreciated.

Cheers

Chris

 

[Red Spot]

Re: New Comer requires a little advice on an unusual Mains Supply to the local pub..

Strange use of colours for single phase, anyway. I would check the neutral, looks like its three into one.....LOL.
The cable is rated at 70 odd amps but it looks like you are spreading the load over the phase cores (well L1 anyway) and returning the lot over one neutral.

Is there anyway you can disappear on holiday for a while without actually touching anything.....Looks like they are going to keep hammering it until something really bad happens. If the DNO put in a slightly higher fuse next time, it could be the next weak link in the pub that goes.
I would check the connection tightness in the Dbs as well this will give you some idea of how hot its been getting.

Ye thats exactly what it is, the three poles from the 63Amp MCB all supply DB2 (again into a Three Pole MCB) all returning down one neutral (16mm) This cant be good practise?

Cheers

 

[Red Spot]

Re: New Comer requires a little advice on an unusual Mains Supply to the local pub..

While trying to sort out a resolution to the main loading issue i would look at doing the below in the mean time for safety reasons; (comments welcome please)

Ask the Supplier to come and remove the incoming split link or change the main fuses to 50Amp (if possible) then at least if the pub draws too much these should go before the fuse by the trasformer or worse the supply cable burns out again. At least then they stand a chance of getting the power back on quickly or only losing power to some of the pub as its split.

But i m not sure if i need to do anything with the supply cable to the kitchen, obviously i will need to let the client know what he can and cant use consecutively.

Any other points to look out for?

Cheers

Chris