RCD tripping at half the rating ?

[Engineer54]

oh ok yea, i didnt know if that was possible? i take it that is still ok to do yea?

Oh Dear, ....It's statements like this that make me wonder what the hell's going on back in the UK these day's!!!

 

[DJ Ovengloves]

Post deleted I can't use multi quote properly!

 

[Octopus]

Oh Dear, ....It's statements like this that make me wonder what the hell's going on back in the UK these day's!!!

E54 - you read this forum everyday and you are surprised??

 

[i=p/u]

Easy when you know how,

 

[AdieB]

If the RCD is MEM then it will not test correctly from the rcd you have to test it downline.
AdieB

 

[Sintra]

If the RCD is MEM then it will not test correctly from the rcd you have to test it downline.
AdieB

Never had a problem with them myself tbh can you explain a bit more.

 

[Darkwood]

Never had a problem with them myself tbh can you explain a bit more.

Most Rcd 's are fine to test at terminals but some are designed in that the coil is connected after the live terminal thus using terminals for testing won't operate the device

Save me explaining it in full read this previous thread ...
.http://www.electriciansforums.net/i...stallations/28288-rcd-testing-no-trip-db.html

 

[AdieB]

As Darkwood says beet me to it . But I have also had no problem with the very latest MEM RCD's but have had a problem with the older units.
AdieB

 

[Darkwood]

Its also the case that some rcd's have remote C.T.'s and this must be tested downstream of these monitors this isnt usually found in domestic but more so commercial and industrial where rcd's monitor over 3ph, i understand this won't ever effect 99% of sparkies out there but just noting it so this thread isn't misleading in saying the RCD's should be tested at the terminals as on occasions this isnt the correct method.

 

[Engineer54]

Most Rcd 's are fine to test at terminals but some are designed in that the coil is connected after the live terminal thus using terminals for testing won't operate the device

Save me explaining it in full read this previous thread ...
.http://www.electriciansforums.net/i...stallations/28288-rcd-testing-no-trip-db.html

Only the one as far as i know. The manufacturers suggestion is to connect 10cm or so of conducters to the terminals and test from the ends these!!

 

[cobrauk]

Yes agree its test at the rcd/RCBO terminals, as its the rcd you are testing not the circuit

 

[Darkwood]

There are plenty that use remote monitoring using current transformers, ive fitted them on occasion and many brands available and yes although this thread is really about Rcd's in standard consumer units i thought it deserves a mention that other rcd devices exist that cant be tested at the terminals in this manor but regarding AdieB noting the older MEM rcd's i believe these were the only one with this issue from a domestic CU point of view.

 

[Engineer54]

There are plenty that use remote monitoring using current transformers, ive fitted them on occasion and many brands available and yes although this thread is really about Rcd's in standard consumer units i thought it deserves a mention that other rcd devices exist that cant be tested at the terminals in this manor but regarding AdieB noting the older MEM rcd's i believe these were the only one with this issue from a domestic CU point of view.

This type of Earth leakage protection where an external CT is used are termed as relay's. The smallest i've seen are 300mA, but most incorporate adjustable settings for both tripping values and time... You wouldn't use a standard RCD tester to test such relay's, a secondary injection test kit is a far more appropriate tool...