Yep, they are designed to be sensitive to protect people, but that also makes them sensitive to lots of little faults aswell....man these RCD's really are a headache
Yep, they are designed to be sensitive to protect people, but that also makes them sensitive to lots of little faults aswell....man these RCD's really are a headache
this sounds fairly normal, so add in a few mA from other appliancs in the caravan, and times that by 20 pitches and you can see how earth leakge can accumulate rapidly.Ok have an update...earth leakage test was done by myself (sparky couldn't carry this out dont ask)
I noticed when the electric heater (build in heater) was turned on the reading was not steady, the average reading for the caravan was around 2.4mA, now when the heater was on the reading was slightly more erratic hunting between 3.8mA and approx 6mA, it would then seem to lower after a while, then after a period would start to deviate again. Is this normal?
Jiggling test leads can cause false readings, if the earth wire is bare copper and you touch it, you just discharged any static from your clothing. If you can't get a repeat reading, it's usually non-sense - it's the sort of thing that experience teaches.Also this may seem stupid and perhaps the problem is obvious however there was a point when the meter peaked out at 20mA! It did not do this again and I thought it was myself doing something with the clamp meter (position / moving it etc) which caused this? For example would touching the earth wire on the outside of the clamp while neutral/live are clamped cause a weird reading? I assumed it was me doing something silly however if there is no way a simpleton like myself cannot use one of these clamp meters then perhaps this was a genuine reading which would give me a result!
Your sparky is probably pissed off with being told how to do his job. Others have mentioned you have accumulation of leakage current causing the 300mA rcd to operate. Get the earth leakage tested at source. You may have to rejig the main incomer to sub boards to get rid of this fault. Chasing it around the campsite haphazardly and telling the sparky your findings will lead him up the garden path. Start from the beginning and let him design the install better is the direction I would go in. The fact that hes to busy to attend tells me hes had enough of this job.
Either that, or he didn’t know what he was doing?
this sounds fairly normal, so add in a few mA from other appliancs in the caravan, and times that by 20 pitches and you can see how earth leakge can accumulate rapidly.
Jiggling test leads can cause false readings, if the earth wire is bare copper and you touch it, you just discharged any static from your clothing. If you can't get a repeat reading, it's usually non-sense - it's the sort of thing that experience teaches.
all test gear is merely 'an indicator' but some are more accurate indicators than others... LOL! 3-4mA is too bad, if you find something showing a steady 30-40mA, or more, then it will have sufficed it's function. As I said before, it really is worth altering your set-up to get rid of the 300mA RCD and oush the RCd protection onto the submains / dist boards around the site.Thank you @binky. I realise the clamp meter I have is probably not great by any Sparky’s standards on here but it seems to also deviate when the meter is at different positions or angles relative to the neutral/live? It can change by 3-4ma by turning it 180 degrees!
Sorry been cut off with the recent storms we have had recently...Thanks @binky I think i was experiencing interference with other wires, still trying to source the culprit, finding this device very interesting actually!all test gear is merely 'an indicator' but some are more accurate indicators than others... LOL! 3-4mA is too bad, if you find something showing a steady 30-40mA, or more, then it will have sufficed it's function. As I said before, it really is worth altering your set-up to get rid of the 300mA RCD and oush the RCd protection onto the submains / dist boards around the site.
I encountered a similar set up many years ago whilst quoting for solar panels on a caravan site down Cornwall. I was glad not to get the job becuse the way the solar inverters start up is good at upsetting RCDs, and the site owner wasn't going to fork out for a complete new cable run of 300m, or interested in paying to change what he had. It made fitting the panels uneconomic anyway.
Improving the setup is the approach I would take for long term reliability as well as making it easier to find current fault.And your layout doesn't look to be the best design to "Minimise Inconvenience In The Event Of A Single Fault"..
(which is a requirement in BS7671 wiring regs)..
@SPECIAL LOCATION thank you. I understand what a ramp test is but do not have the equipment or knowledge to carry out such a test - I hope the contractor will undertake this in due course.
For if or rather WHEN this happens again ...can we safely assume that (going back to the scenario which I have illustrated above) shows 100% that the individual pitch is causing the fault, there cannot be any other influencing factor which would trip the individual RCBO on the pitch other than this caravans load and/or earth leakage?
Thanks for all the help on here its been great
I had this fault the other week 300ma time delayed sub main feeding a main building from there 100ma time delayed feeding 4 other buildings each having their own CUs all rcboOP - you need a decent, competent LOCAL spark to advise you on this - a single up front RCD tripping is a VERY BAD thing to have
I had this fault the other week 300ma time delayed sub main feeding a main building from there 100ma time delayed feeding 4 other buildings each having their own CUs all rcbo
Kept randomly tripping the 300ma turned out that there was n to earth leak on the cable and a n to earth fault in one of the buldings on a light circuit ... the problem was that they were not DP rcbos so when rcbo tripped in building the n to earth fault still remained.
[...can we safely assume that (going back to the scenario which I have illustrated above) shows 100% that the individual pitch is causing the fault,
Erm.. NO..
from what I understand and have read.. you haven't actually PROVED much so far..
Basic essential rule is..
"Assume EVERYTHING is faulty until you have PROVED otherwise"..
So far without any ramp tests you haven't actually PROVED that you don't have an oversensitive RCD, (or multiple oversensitive RCD's).
So..
IMHO you have got to test and prove the FULL operating characteristics of each & every RCD..
Plus the insulation resistance values for each and every circuit supplied by those RCD's..
Then look at what is regularly connected and if any natural leakage is evident...
(Sorry if I have missed something you have already stated..
But I think there are still too many unknowns that need to be resolved.)
Was this
He's going to spend money, even if he decides to have a go himself and buy a cheap mft and then learns how to use it.100% agree but the OP thinks they can solve this without spending money
@SPECIAL LOCATION thank you. I understand what a ramp test is but do not have the equipment or knowledge to carry out such a test - I hope the contractor will undertake this in due course.
For if or rather WHEN this happens again ...can we safely assume that (going back to the scenario which I have illustrated above) shows 100% that the individual pitch is causing the fault, there cannot be any other influencing factor which would trip the individual RCBO on the pitch other than this caravans load and/or earth leakage?
Thanks for all the help on here its been grea
The first thing to do is IR test the supply cable from the 300ma rcd to the dis boards.@SPECIAL LOCATION thank you. I understand what a ramp test is but do not have the equipment or knowledge to carry out such a test - I hope the contractor will undertake this in due course.
For if or rather WHEN this happens again ...can we safely assume that (going back to the scenario which I have illustrated above) shows 100% that the individual pitch is causing the fault, there cannot be any other influencing factor which would trip the individual RCBO on the pitch other than this caravans load and/or earth leakage?
Thanks for all the help on here its been great
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