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Discuss RCD Tripping in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

EddieB

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Arms
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I was called out to a friends the other day he was experiecing the RCD trip problem you know the one, it trips you reset, 1 hr later it trips again you reset it, 3hrs later etc etc . I had a look at the circuits and found a ring that was down to .1 of a Meg Iinvestigated further and found the problem to be an anti surge multi plug the kind the PC, Printer etc plugs into. After unplugging it the readings went to >100meg, he had 2 in the house different makes but about the same readings. Could this have been the offending item (s) and has anybody else experienced this problem with this kind of product
 
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E

electro

hi
It's probably the neon on the extention lead? Giving you those readings. Its not going to trip a RCD though, not unless you have loads of PCs and monitors, more than lightly its a appliance connected to the circuit.
Regards
 

EddieB

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  • Thread Starter Thread Starter
  • #3
It was a low reading to earth not between, The neon is across the L & N I dont think the earth is involved other than what goes on inside the multiplug that causes it to be surge resistant.
 
G

Guest123

Hey.

Just a point, surely you would have un-plugged everything before doing an insulation resistance test on a circuit???
 
E

electro

Hi


If the is low reading is to earth and then its the oxide varistor in side the surge unit. My advise would be don't test with surge units connected as your likely to damage them and get very low readings. These units can go faulty and give a leakage to earth. Did you try the ramp test on your RCD? Just to make sure it's not a sensitive one..


Regards
 

EddieB

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  • Thread Starter Thread Starter
  • #6
Len, It's a very busy three bed house with no guide to show me around I unplugged what I could find and started delving into cupboards and walldrobes after I found the low reading.
Electro I did ramp test and it tested out fine
thanks guys
 

ian.settle1

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It was a low reading to earth not between, The neon is across the L & N I dont think the earth is involved other than what goes on inside the multiplug that causes it to be surge resistant.
The problem may be that one of the surge components which is connected from L-E breaking down.
 
D

desertbootz

Surge protection shunts spikes (over-volts) to earth. Insulation testing generally squirts 500V into the cct doesn't it? Most of that is going to be seen as a surge and go through the MOV and give a low Ohm reading?As always I am ready to be shot-down but isn't it more likely/possible that a faulty Switch-mode PSU in a PC or such like is dumping onto the earth to cause the RCD trip?
 
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ian.settle1

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Mentor
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Surge protection shunts spikes (over-volts) to earth. Insulation testing generally squirts 500V into the cct doesn't it? Most of that is going to be seen as a surge and go through the MOV and give a low Ohm reading?As always I am ready to be shot-down but isn't it more likely/possible that a faulty Switch-mode PSU in a PC or such like is dumping onto the earth to cause the RCD trip?
Most PC's filter circuits are connected to earth but should be approx 3.5mA which is not enough to cause RCD to trip, could be surge components breaking down now and again if it is not constantly tripping but at different times.
 
D

desertbootz

Most PC's filter circuits are connected to earth but should be approx 3.5mA which is not enough to cause RCD to trip
Yr right that only about 3.5mA leakage should be present but bad design, low quality components, component filure, etc. could all contribute to an increased current to earth. What if the dialectic were breaking down at some peak value?

could be surge components breaking down now and again if it is not constantly tripping but at different times.
Could be but then again the surge components are usually MOV and semiconductors tend to break 'once and for all' rather than 'now and then' no matter what Schroedinger said about his cat.

My monies still on SP causing low ohm, SMPSU causing the RCD trip and STD's causing an itchy scrot.
 
I was called out to a friends the other day he was experiecing the RCD trip problem you know the one, it trips you reset, 1 hr later it trips again you reset it, 3hrs later etc etc . I had a look at the circuits and found a ring that was down to .1 of a Meg Iinvestigated further and found the problem to be an anti surge multi plug the kind the PC, Printer etc plugs into. After unplugging it the readings went to >100meg, he had 2 in the house different makes but about the same readings. Could this have been the offending item (s) and has anybody else experienced this problem with this kind of product
Hi Eddie,
Did removal of you anti surge plug stop your tripping?
 

Des 56

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Arms
Esteemed
When doing an insulation resistance test in a domestic It is worthwhile adding as a matter of habit one more test to the recommended
Do a 230 volt between lives and earth and between lives to be sure the circuit you are testing is actually neon and appliance free.
This gives assurance that you will not damage sensitive electronic equipment that may have been overlooked for isolating by applying the 500 volt initially

If the insulation resistance tests are sound,then the rcd function is sound
Reconnect the electrocic equipment and retest the rcd on the non trip scale

Whilst most are concentrating on the anti surge readings being perhaps the problem I very much doubt that this is the case
The possibility is that an item such as a fridge freezer or such as earth leakage problems with stat controlled functions
Have you also insulation tested the household appliances for any low
neutral earth readings, Items that may have been left plugged in during the tripping episodes
These may not be enough on their own to cause the tripping ,but when left plugged in with heavier loads applied, they could be the culprit

Intermittent tripping is unfortuately the biggest nuisance for the householder and the spark to deal with
 

EddieB

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Arms
  • Thread Starter Thread Starter
  • #13
It has not occured since, so it makes you wonder.

Des 56
it was the first thing I did,I always go through with 250v if I'm not sure if I missed anything that may be plugged in
 
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