Advice suggestions please

[domestic spark]

Gone to a job this morning had a call from a customer when i plug too much I'n on this side of the kitchen it trips the whole house, house DB protected by 30ma rcd. Went to the job apparently this has been the case for 4 years or more. Happens then washing machine is on and toaster and kettle is used. Trip it now appears that 2x sockets on one side are on the ring. Over the other side on t&e goes down the wall to feed a socket above worktop, spur from this to under cuPboard lights, spur to socket below worktop to wm outlet, spur from this to tumble dryer, spur from this to double socket on worktop further over. Bingo! Problem solved overloading one t&e radial, from ringmain, must be jb above ceiling! All faceplates nackered a right mess under cupboards t&e lashed everywhere and you should only spur off once I've said best option is to run a new circuit. All old stranded cable however insulation resistance tests all good etc. Just to sort it all properly. It will take me a day on my own to complete and test, dabbing new ring into existing board surface trunk above units then drop behind units for 5 double sockets and 3 spurs for appliances. Was going to go I'n at 400 pounds does this sound fair ?

 

[Guest 004]

So the rcd is tripping the whole house, and IR are ok? sounds like some appliances are leaking current, the fixed wiring although a mess has returned satisfactory results.

 

[telectrix]

sounds a fair price. only suggestion is might it be easier to run 2 radials, 1 to each side of the kitchen. use 4mm for the heavily loaded side at 32A and 2.5mm at 16A for the other side.

 

[Chr!s]

Gone to a job this morning had a call from a customer when i plug too much I'n on this side of the kitchen it trips the whole house, house DB protected by 30ma rcd. Went to the job apparently this has been the case for 4 years or more. Happens then washing machine is on and toaster and kettle is used. Trip it now appears that 2x sockets on one side are on the ring. Over the other side on t&e goes down the wall to feed a socket above worktop, spur from this to under cuPboard lights, spur to socket below worktop to wm outlet, spur from this to tumble dryer, spur from this to double socket on worktop further over. Bingo! Problem solved overloading one t&e radial, from ringmain, must be jb above ceiling! All faceplates nackered a right mess under cupboards t&e lashed everywhere and you should only spur off once I've said best option is to run a new circuit. All old stranded cable however insulation resistance tests all good etc. Just to sort it all properly. It will take me a day on my own to complete and test, dabbing new ring into existing board surface trunk above units then drop behind units for 5 double sockets and 3 spurs for appliances. Was going to go I'n at 400 pounds does this sound fair ?

Will this new circuit be protected by the single consumer unit RCD?

 

[domestic spark]

cause for tripping i came up with was OVERLOAD and yes carried out a full test on circuit and came up trumps. one side of kitchen 0.07, 0.06, and 0.04/5 readings on r1+r2 readings, over the other side where a visuall confirmed, a spur from ceiling for double socket on counter to another undercounter and a spur spur and one final double socket, leg came up through boxing and fed another double further alond the counter.

OVERLOAD? max amperage for one 2.5mm cable approx 21a at best?? and if you plug in kettle whilst washing machine is going??

 

[domestic spark]

r1+r2 readings over other side were 0.24, 0.28, 0.32, 0.44 at last point (double socket) confirms its a radial (spur off spur off spur)

 

[domestic spark]

Will this new circuit be protected by the single consumer unit RCD?

yes it will

 

[Guest 004]

You said the whole board is tripping, so is it the RCD Or MCB

 

[domestic spark]

non rcd fuseboard, hager, all MCB'S protected by a seperate 30MA RCD thats been added at some point of the installations life. so this enables all MCB's to now be 30Ma protected.

 

[Guest 004]

r1+r2 readings over other side were 0.24, 0.28, 0.32, 0.44 at last point (double socket) confirms its a radial (spur off spur off spur)

why dont you just fuse down from where its spurs off as in reg 433.1.5

 

[domestic spark]

it trips this when TOO MUCH load is applied to this side of the kitchen been like it for over 4 years! i was told

 

[Guest 004]

what trips!

RCD or MCB?

 

[domestic spark]

RCD trips

 

[domestic spark]

Main switch and all MCB's stay up. trips the seperate, 30Ma RCD unit installed. which covers all MCB's within the DB.

 

[domestic spark]

r1+r2 readings over other side were 0.24, 0.28, 0.32, 0.44 at last point (double socket) confirms its a radial (spur off spur off spur)

my cause for concern as to why its tripping RCD unit. OVERLOAD! especally as its a spur off a spur off a spur etc.
​

 

[Guest 004]

So once you rewire, and the fault is still there what are you going to do?

If it was overload it would trip the individual MCB

 

[domestic spark]

being a numpty. hob was original cause for 30Ma RCD to trip whole house! i dissconnected that.

My secondry problem was indeed MCB tripping Kitchen ring, when 2 or more appliances were plugged in over one side! however this fault is the intermittent one over past four years. Make sense now?

 

[Guest 004]

being a numpty. hob was original cause for 30Ma RCD to trip whole house! i dissconnected that.

My secondry problem was indeed MCB tripping Kitchen ring, when 2 or more appliances were plugged in over one side! however this fault is the intermittent one over past four years. Make sense now?

Yes now we have the full picture, what size mcb was it?

 

[domestic spark]

32a hager

 

[Guest 004]

B or C

 

[domestic spark]

type b

 

[domestic spark]

domestic installation

 

[Guest 004]

ok lets think about this, so if you rewire into a ring, and plug these appliances in, do you think it will stop tripping the 32 amp 'b; breaker?

 

[domestic spark]

what your saying is as its already on a 32a breaker, it would need approx 40a to trip.

 

[domestic spark]

which is greater than 3 appliances plugged in

 

[domestic spark]

MCB tripping as 2.5 spured from ring feeds, 2 or more appliances, kettle toaster w/m, one single 2.5 max 27a depending on installation methords so at best, so this side of kitchen is clearly overloaded?? thats my logic?

 

[domestic spark]

for MCB tripping

 

[domestic spark]

but no i dont want to do the job and for the problem to still occur!

 

[Guest 004]

lets not get confused with cable ratings for the minute, as you have done an IR test, the cable has stood the test of the current of these machines, I trust you got >200M

 

[domestic spark]

>500 flukes

 

[Guest 004]

so the cable is sound, and not breaking down, although insufficient to BS7671, the cable will not cause the mcb to trip right?

 

[domestic spark]

so im on the wrong lines, and if i rewire all correctly, im going to look a fool! as i wouldnt have solved any problems?

 

[Guest 004]

2 new rings might sort it, or he's got a duff cooker, along with the duff hob

 

[domestic spark]

let me explain, cooker 6mm radial, 32 type b MCB, Hager.

from cooker switch oven is connected to outlet, from outlet a s/so with hob plugged in (plugtop) this is what was tripping, RCD, knocking out all power to DB. dissconnected that. problem solved. he told me, was a bit silly cleaning it soaked it and hadnt worked since then. (TRIP)



APPLIANCES on KITCHEN RING, toaster, kettle, t/d, w/m, fridge.

when too much is plugged in over the "spured side" thats when MCB tripps

 

[Guest 004]

do a load test on each appliance, one at a time.

 

[domestic spark]

what plug each appliance in on there own? and see if one causes ring to trip

 

[Guest 004]

Do you not have a clamp meter?
Do you remember the principles of Kirchoff's current law?

 

[domestic spark]

i dont have a clamp meter no.

Do you remember the principles of Kirchoff's current law?

never tought it

 

[Guest 004]

ok, if you change the circuit to a ring, you will still have the same amount of current flowing through the MCB, regardless of spurs etc, with everything plugged in, so the MCB will still trip.

 

[domestic spark]

yes but load will be equally shared, no overload to cables

 

[Guest 004]

the same amount of current will still flow through the MCB

 

[Guest 004]

Look up Kirchoff current laws, it is very interesting, and one of the first principles that I learnt at college.

God knows what they teach these kids nowadays

 

[domestic spark]

how too pass quickly lol

 

[domestic spark]

is the most probable cause to all this was because the spurred 2.5mm leg was overloaded at times causing MCB too trip? this logic IS possible?

i just didnt want to rewire and the same problem to occur! how silly would I look!

i just want too make sure there was logic in my conclusion!

 

[Des 56]

Can you run a new cable 4mm to feed half the overloaded side on a 32 amp mcb
The existing 2 feeds will become 2x20amp radials

Ending up with 2x20amp radials and one 32 amp radial
Spreading that load should help rather than trying to solve it by using rings

 

[domestic spark]

i see your logic, no spare ways in db unfortunatly

 

[Guest 004]

is the most probable cause to all this was because the spurred 2.5mm leg was overloaded at times causing MCB too trip? this logic IS possible?

No, might have caused a fire though

 

[domestic spark]

No, might have caused a fire though

looks to be more involved than i thought, are we any clearer as to cause? of course ill have to pop back at some point and see if anything upstairs is stealing power from the kitchen ring. mite shed some light HOPEFULLY.

 

[Guest 004]

You need to do load test, before anything else.

 

[domestic spark]

How do i do that?