Memera 21 RCD Tripping

[Shropshire]

Hi,

The main RCD is intermittently tripping on our Memera 21 (RCD is 404elhnc). I've gone through the process of unplugging everything but it still trips intermittently.

The coincidence of when this started was there was some work done on the pole feeding our property by the distribution company (I don't know what they did though), the day before it started tripping.

Could this be the cause or is it just a coincidence?

Thanks

 

[Shropshire]

Update: I contacted National Grid (used to be Western Power Distribution) who were extremely helpful. They contacted the team that were out last week and it seems that they moved 2 other customers onto our phase and isolated a particular part of the overhead power in preparation for some trees that are being cut down at a nearby property next week. They got the engineers that did that work straight back out and moved us onto a clean phase (away from the other customers). So we will see if that has sorted it. Very very impressed with how quickly they sorted it as I only rang them at 10:45 this morning and by 12:00 they were out and had sorted it!

 

[ericmark]

Thank you very much for the report, I know in my last house, every so often we would get a batch of RCD's tripping, and never found a fault, and then it could go for years with no trip, fitted early 90's. I had always blamed it on spikes on the supply, nice to see some one else has experienced the same.

The result was when I moved, new house all RCBO and SPD fitted. The problem is one does not know if this has saved any erroneous trips or not, spikes should not really trip RCD's, but it seems they do.

 

[Shropshire]

Update: I am pleased to say that the work they carried out (as above) seems to have cured the problem (albeit they created the fault in the first place!) The RCD was tripping every 5 hours or so before. Its now been on 48 hours and not tripped.

 

[Taylortwocities]

Interesting to see (another) report of a house RCD that trips due to influences on the supply.

Often we expect an RCD to only be concerned with what is happening on the consumer circuit side. But it seems some DNO gremlins can cause issues.

Theories please!

 

[flameport]

Theories please!

Voltage transients
Other mains-borne interference
Electromagnetic effects such as those caused by diverted neutral current or the proximity of other radio frequency devices such as smart meters, WiFi items and plenty more.

The main RCD is intermittently tripping on our Memera 21

While it may now be working (as in not tripping), it's been obsolete for decades.
Consumer unit replacement overdue.

 

[Adam_151]

I've seen a loose connection in a henley block before the RCD main switch board course it to trip, apparently normally when the vacuum cleaner was on. I'd gone in expecting a N-E fault of a few hundred K or so, and leaking to earth depending on loading, but I'd done an IR on the board, got something just over a meg which wasnt great but wasn't the cause of the problem unless it also varied a lot lower and was mostly due to one lighting circuit IIRC, had put the board back together and powered up and tested the RCD as being all fine, I was sat there scratching me head over it when I was asked if I wanted a tea. Kettle goes on and neutral starts crackling away, nothing trips. After the kettle had boiled I remade the henley block and all was fine. My thoughts are the arcing connection when combined with the motor load must have resulted in some very fast spiky bits on the voltage waveform, either that confused the electronics in the RCD, or simply because of the high frequency components, there was much increased leakage over any L-E capactance in the system, whether that just be cable runs, or filters in power supplies etc.

 

[winston1]

While it may now be working (as in not tripping), it's been obsolete for decades.
Consumer unit replacement overdue.

Why, it's working, it's metal? I hate this throw away society.

 

[SUNRAY]

Interesting to see (another) report of a house RCD that trips due to influences on the supply.

Often we expect an RCD to only be concerned with what is happening on the consumer circuit side. But it seems some DNO gremlins can cause issues.

Theories please!

A real moan tonight...

It is one of those 'several people have had a look so can you go in and sort it out' jobs, I popped in to aquaint myself with it with the expectation I'd get the call when required. This is an outbuilding [happens to be an ex telephone exchange] currently used as changing room and pump house...

www.diynot.com

Was an outbuilding with no found imbalances etc on the feedfrom the Henley or the building installation but long term intermittant RCD tripping. The only thing I found being the imported earth from DNO being linked to the buildings TT tystem, which it turned out was the only earth on the substation due to metal theft. Once the DNO sorted their bit and the SWA termination abortion was put right by securely insulating the armour from the rest of the system (so as not to import the DNO earth to the outbuilding) the RCD tripping problem went away, however another property along the road started started having problems.

 

[Taylortwocities]

Why, it's working, it's metal? I hate this throw away society.

There are things that do need throwing away.

 

[SUNRAY]

Consumer unit replacement overdue.

Why?
An excellent quality product made to a high standard by a reputable company.
I know of a number in use without problems, 2 in particular get tested at least every year and all of the MCB's and RCD's are well in spec.

 

[winston1]

Work creation. The reason people come on here saying they don't trust tradesmen.

 

[Taylortwocities]

 

[sparkwright]

Why, it's working, it's metal? I hate this throw away society.

I know what you mean.

I think the MEM 21 stuff was mid 80s, so something like 35 years old.

An electrician certainly should mention if something is out of date, not to current regs - and even 'obsolete' - though not sure if 'obsolete' qualifies as a good reason to change it.

It is a shame some old gear can't be left alone to get a bit more mileage out of it - though I suppose the problem is in reality there is FAR TOO MUCH old gear of varying vintages still out there.

It's got to the stage where stuff I consider to be still quite new, and serviceable is being eyed up to be stripped out.

Too many new rules and requirements only invented to create jobs for people.

 

[SUNRAY]

It's got to the stage where stuff I consider to be still quite new, and serviceable is being eyed up to be stripped out.

I've seen far too many CU's replaced for absolutely no reason and not only that I knew of one rental property which has had 4 CU's in 6 years. OK the first was a wylex fusebox and I quite happily accept it was overdue. next was a plastic CU with RCD as main switch then split board now split board with 3 RCDs & 6 circuits plus SPD and it's fuse. I can already see it changing because of the fuse and again for RCBOs.

And a village hall maintained by a friendly sparx to a good standard for years, had the nerve to kick the bucket. Next person in condemmed the 6 plastic CUs (selection of split boards & RCBO) in different rooms and changed to metal all RCBO then 2 years later another company gave some cock and bull story about single point and stripped the system of submains and brought a couple of dozen radials to a DB by the meter and keeping an area on a phase means the RCBOs are spread around the DB. In principle that doesn't sound like a problem except one of the rooms is basically a built on external store room with internal access into the hall and the CU is off of the small meeting room, this means the first time a RBCO tripped they had to pass through 2 areas booked to others (one of which was a wake) and the kitchen. The stage has 4 circuits; flou lights, 13A socket ring on sound limiter and powered down when not in use, 2x 32A dimmer supplies, one has to access the small room to power up or down and again it may be in use at the time. The small room is roughly 15ft square and the DB is in a cupboard in a far corner so often obstructed by table/chairs when in use.

Too many new rules and requirements only invented to create jobs for people.