B
bigbaddave
Afternoon all
Been to a job through the holidays, Large domestic house in the sticks with a seperate house built on the land for the grandkids all fed off one supply.
They are reporting nuciness tripping and be no aparange pattern to when things trip, to give you an idea on the instal TT system. 100ma main RCD feeding a number of seperate 30MA Rcd's consumer units. Anyway the RCD that is tripping is situated in the main buiding feeding another DB in the seperate house. Its a sole RCD and only feeds the db in the second house.
Testing, First start by ramp test with no load, RCD trips at 18ma. Then do a global Ir (From Rcd and including all load on that rcd) and comes back less than 1meg.. 0.709 to be precice. Testing each curcuit individually and all curcuits over 1meg.. Now with all loads on each curcuit testing individually for earth leakage, 10 curcuits in total feeding a number of items. Each circuit was testing for earth leakage seperatly by isolating and running one at a time with full load (Well most of the larger items). Anyway the combined leakage on all the curcuit came back at roughly 15.4 ma. Rcd ramp test on full load and trips as soon as I hit start. to confirm there is leakage on all curcuit from 1-3 Ma. Nothing obviuous just a number of computers and fridge freezers in the garages which is also fed from this board. Load of forecent lighting (Bad spelling i know)
Firstly.. Earth leakage due to low IR value's. I make it 230/0.018 (18ma) = 12777 Oams 0.012777 Moams. Therefore not the problem. Or should this be multiplied by how many amps (Load) is applied to the curcuit or is it just a factor of 1?
I have discussed with the guy and he has asked for a new fusebox (His words not mine) to be installed in the second house and therefore removing the one 30ma RCD covering the board (Still 100ma protected) and protecting it with RCBO board covering all curcuits therefore everything is still RCD protected. Its having a new board fitted regardless to ensure that the grandkids can reset it if it trips.
With the Earth leakage being low on individial curcuits would you guys be happy? as i say the guy want new board fitting anyway as its the old rewireable and the grandkids dont know what to do in the event it blows
Been to a job through the holidays, Large domestic house in the sticks with a seperate house built on the land for the grandkids all fed off one supply.
They are reporting nuciness tripping and be no aparange pattern to when things trip, to give you an idea on the instal TT system. 100ma main RCD feeding a number of seperate 30MA Rcd's consumer units. Anyway the RCD that is tripping is situated in the main buiding feeding another DB in the seperate house. Its a sole RCD and only feeds the db in the second house.
Testing, First start by ramp test with no load, RCD trips at 18ma. Then do a global Ir (From Rcd and including all load on that rcd) and comes back less than 1meg.. 0.709 to be precice. Testing each curcuit individually and all curcuits over 1meg.. Now with all loads on each curcuit testing individually for earth leakage, 10 curcuits in total feeding a number of items. Each circuit was testing for earth leakage seperatly by isolating and running one at a time with full load (Well most of the larger items). Anyway the combined leakage on all the curcuit came back at roughly 15.4 ma. Rcd ramp test on full load and trips as soon as I hit start. to confirm there is leakage on all curcuit from 1-3 Ma. Nothing obviuous just a number of computers and fridge freezers in the garages which is also fed from this board. Load of forecent lighting (Bad spelling i know)
Firstly.. Earth leakage due to low IR value's. I make it 230/0.018 (18ma) = 12777 Oams 0.012777 Moams. Therefore not the problem. Or should this be multiplied by how many amps (Load) is applied to the curcuit or is it just a factor of 1?
I have discussed with the guy and he has asked for a new fusebox (His words not mine) to be installed in the second house and therefore removing the one 30ma RCD covering the board (Still 100ma protected) and protecting it with RCBO board covering all curcuits therefore everything is still RCD protected. Its having a new board fitted regardless to ensure that the grandkids can reset it if it trips.
With the Earth leakage being low on individial curcuits would you guys be happy? as i say the guy want new board fitting anyway as its the old rewireable and the grandkids dont know what to do in the event it blows
