How to Carryout the RCD Ramp Test - Why Does my RCD Keep Tripping

so in this video today okay we're going to be  looking at the RCD ramp test now this part of   any EICR and the customer said that every now  and then the one with the big yellow button   okay trip sometimes so can we sort of look into  it while we're here now we've done the insulation   resistance test okay so sometimes when you have  a device that's tripping you would maybe go to an   insulation resistance test to make sure if it was  an overcurrent protective device that there's no   shorts between line and neutral or there's nothing  between line and CPC or line and earth or neutral   and earth being an RCD now they've come back  absolutely fine so our next point of call okay   is going to be the ramp test which we can  use not necessarily for initial verification   okay there there's no necessity for it however  it is a handy test to do when we're talking about   fault find it now this is a live test okay so all  precautions need to be taken GS38 insulated tools   etc PPE however even though it's a live test i  still have managed to isolate as much as i can in   the board okay just to take away a little bit of  the risk now it's not going to take away all of it   however by not having absolutely everything  in their live when i don't need it to be   it's going to help me do this live test a little  bit safer okay now we're going to do it at the RCD   itself okay as manufacturers specify you should do  it at the RCD with no loads and with the ramp test   you're not really going to want the loads on  anyway because we need to find out what the   RCD is actually tripping at in terms of how much  current it's going to take to disconnect this RCD   without any electronic devices in circuit which  are maybe giving natural earth leakage okay which   might reduce that reading we're going to get  now all we're going to do is we've probed onto   the earth bar okay and on our test here as you  can see we've got the usual half times one times   five times an auto which you can watch that in a  different video that'll appear on the screen now   but we're actually going to go to this symbol  over here okay which is indicating a ramp   test we select the milliamp rating of the RCD  which is 30 milliamps again this installation   all we're going to do okay is we're  going to go on the load side of the RCD   it will show us the voltage and now what it's  actually doing is it's not giving us a time as   you can see it's given us 21 milliamps  so the testers is slowly ramping up the   the current in stages to find out exactly what  milliamp will disconnect this RCD and usually   we think oh it's a 30 milliamp RCD it's going  to disconnect at 30 milliamps it's rarely the   case that you get it that high is usually around  i find 22 23 this one is showing us 21 milliamps   we'll do it on both sides of the cycle so now  we're on 180 degrees we'll re-energize the RCD   and we'll do this again now obviously that was 21  milliamps so we wouldn't really expect there to be   a problem and we have 21 milliamps again okay and  that's there or thereabouts on what we want it to   be now if that had come back slightly lower let's  say 13 14 milliamps then we might want to question   actually is the RCD tripping intermittently  because of all the electronic devices in the   circuits now on a small domestic dwelling like  this that wouldn't massively be too much of a   problem not saying this wouldn't be the case but  you'd have to see what is actually installed here   but this is why BS7671 states that we're only  allowed a maximum of 30 percent of the rated   residual current of the RCD so this one  that being 30 milliamps okay of natural   earth leakage on any one RCD so that would mean  we're on this installation actually on this RCD   only allowed nine milliamps of natural earth  leakage before we'd have to think about splitting   the circuits up and that is another benefit of  an RCBO really because actually this RCD has four   circuits on it so that nine that thirty percent  comes from all of these whereas if these were   individual RCBO's only the individual circuit  would have the 30 not all added together now   if this come to let's say 13 milliamps okay you  might think oh well that's still not too much of   an issue but let's say that 9 milliamps okay we  had used that 30 percent that when everything's   actually turned on it means the RCD effectively  already has there's already nine milliamps of   earth leakage okay which the RCD is detecting  if he's tripping about 13 milliamps that means   it's right on the edge and it's only looking  for another sort of four milliamps before it   starts to disconnect we have to look at the whole  installation of how it's installed now this RCD   is fine okay the insulation resistance test come  back fine the RCD ramp test okay remember we're   not looking at times we're looking at the amount  of current it's going to take to disconnect it has   come back fine also so our next step maybe would  be a clamp meter okay so we can turn everything   on in the installation and find actually on  these four circuits how much natural earth   leakage is being used again a small property like  this probably not going to be a massive deal it's   also important to say to the customer okay i've  done these checks okay let's assume we've done the   clamp on ammeter and we've checked the natural  earth leakage and it's fine again usually when   an RCD is tripping it is usually down to a faulty  appliance so this is where you can maybe talk to   the client or the customer and say let's get a bit  more information is it happening at a certain time   is it where you've plugged in an appliance does  it sort of fall when that happens if not maybe   over the next few weeks keep a sort of list stock  or keep an eye out for all these things you know   are using is happening at a certain time is it  happening when you're using certain appliances is   it happening when you're using too many appliances  together okay and then call me back and we can   sort of come back and and have a look at that  generally nine times out of ten in my experience   it is down to a faulty appliance somewhere as  always we hope this video has been some help

Channel: GSH Electrical

Views: 17,080

Keywords: RCD Ramp Test, My RCD Keeps Tripping, My RCBO Keeps Tripping, My RCCB Keeps Tripping, How to carryout a ramp test, RCD Ramp, Ramp Test, Testing RCDs, How to test an RCD, RCD, RCCB, RCBO, Earth Leakage, Earth Leakage Fault

Id: Mxv3OVVjANs

Length: 5min 55sec (355 seconds)

Published: Sun Jul 31 2022