Bulk Workwear - Clothing Suppliers for the Whole Forum Network
This official sponsor may provide discounts for members

Discuss Faulty rcd? in the Electrical Forum area at ElectriciansForums.net

M

Marbles

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:  American Electrical Advice Forum

Domestic installation, rcd tripped on supply to garage which then feeds a barn 25 metres away via swa. supply cable to garage is swa and tests out fine on insul res and continuity as does swa to barn. connect any load to con unit in barn even with no earth and rcd trips? Circuits in barn show healthy insul res readings? any ideas chaps?
 
S

StuSpiers

  • Thread Starter Thread Starter
  • #2
did you do a full rcd test + ramp test.
 
M

Marbles

  • Thread Starter Thread Starter
  • #3
ran out of time today will try tomorrow, seems strange that with good insul res readings the rcd trips even with a pendant connected across supply?
 
S

StuSpiers

  • Thread Starter Thread Starter
  • #4
Well an rcd test will take the guess work out.

did you carry out all IR tests?

L - N, L - E, N - E

Is pme exported?
or is it on a seperate spike?
 

Taylortwocities

-
Arms
Esteemed
Is this a brand new installation, or an existing one that has mysteriously started to have this problem.

If it's new, it sounds like a neutral in the wrong busbar, or neutral link not taken out between busbars in an RCD consumer unit.
 
M

Marbles

  • Thread Starter Thread Starter
  • #6
its an existing installation with a new 17th edition twin rcd board bin added, yes insul res tests done between all conductors?
 
A

adamh

  • Thread Starter Thread Starter
  • #7
does the test button on the rcd work?
 
M

Marbles

  • Thread Starter Thread Starter
  • #8
yeah test button is functioning
 
A

adamh

  • Thread Starter Thread Starter
  • #9
as others have said do a ramp test on the rcd. If all is well try disconnecting each circuit individually and then loading the installation to rule out the possibility of parallel paths.
 
D

Deleted member 9648

  • Thread Starter Thread Starter
  • #10
its an existing installation with a new 17th edition twin rcd board bin added, yes insul res tests done between all conductors?
Are you saying you've replaced the CU to an existing install?....if so you've got a N in the wrong bar.
 

Taylortwocities

-
Arms
Esteemed
yeah test button is functioning
That is NOT how you test an RCD.

The test button is a very basic functional test.

From the sound of it "someone" has done a board swop and mixed up the neutrals.
That "someone" also has not done the required tests on the existing and the altered installation.
 

telectrix

-
Mentor
Arms
Esteemed
check also the manufacturers internal tails in the CU. it is not unheard of to find an incorrect connection.
 
O

Octopus

  • Thread Starter Thread Starter
  • #14
Anything plugged in?

Got called back to a CU change, which I had completed on Friday, on Saturday morning - customer had tripped the RCD when plugging in a 4 way extension. I took the cover off the plug of the extension and the N-E were reversed. He did look a tad embarrassed!
 
M

Marbles

  • Thread Starter Thread Starter
  • #15
neutral connection for a lighting cct found to be in the wrong bar on investigation, have done new checks for customer and circuit is behaving itself. rcd tests were o.k. thanks
 
A

adamh

  • Thread Starter Thread Starter
  • #17
That is NOT how you test an RCD.

The test button is a very basic functional test.

From the sound of it "someone" has done a board swop and mixed up the neutrals.
That "someone" also has not done the required tests on the existing and the altered installation.
if the test button wasn't functioning would you class this as a satisfactory condition for an rcd? i think not!!!

I was doing a test the other day on a council property changed main s/w for an 80A / 30mA RCD as soon as the starter on the 2d or 5ft fluorescent fitting tried to fire the rcd would trip. Ir tests showed no problem but on a ramp test the RCD wasnt tripping untill 150mA also the test button wouldn't work! I swapped the rcd still the same problem, with the rcd isolated from all final c/cts the test button would work! it turned out to be a parallel path for the neutral with there being 2 supplys to the flat , 1 being economy 7 and with there being only 1 terminal for neutral in the time switch for the immersion and night heating whoever fitted it just doubled them up. So I would say checking the test button might not be a bad place to start as I'm sure you would do this anyway as part of testing???
 

Taylortwocities

-
Arms
Esteemed
if the test button wasn't functioning would you class this as a satisfactory condition for an rcd? i think not!!!
Indeed it is not a satifactory condition. My response was as a result of the interchange relating to if the RCD had been tested and the response was
yeah test button is functioning
.

If I remember my training, the RCD is tested re ½, 1x and 5x the nominal op current as part of the live tests. These results go on the cert. The working of the test button is a functional test. and (again if i remember my training) the functional test on an installation is the very last thing that takes place after all the other dead and live tests have been carried out.

I agree, an RCD will be rejected if the test button does not work because that is the user's only belt and braces method of knowing that the RCD functionally works.
 
A

adamh

  • Thread Starter Thread Starter
  • #19
my point was the the rcd was fine but the test button still didnt trip the rcd due to the parallel path.
 
Aico Carbon Monoxide Detectors
This official sponsor may provide discounts for members

Reply to Faulty rcd? in the Electrical Forum area at ElectriciansForums.net

Electrical2Go - Online Electrical Supplier
This official sponsor may provide discounts for members
Top Bottom