RCD trips every morning between 08.00 and 09.00

[marconi]

The voicemail is not correct, or not totally correct. Let me explain.

The top left ENEL Arriva is where the main supply enters. It is a 32A circuit breaker which will trip on short circuit and prolonged overcurrent (as I described earlier). In its case, the 32A will hold for 1 hour at 1.13 x 32A and definitely trip after one hour on 1.45 x 32A. It is not sensitive to black out or brown out that is voltage because it is a passive device concerned with current effects(-but see later at # below). If it trips then you either have a short circuit fault happening or you are drawing too much current - see the hour figures I mentioned. The output of this circuit breaker supplies the RCD breaker (F202?) immediately to its right and the ds642p.

For clarity the ds642p is three in one unit as I explained in my first message, so this is all one device and the black switches will trip down on shprt circuit, overload or high earth leakage:



Did you do my test to discover if the RCD breakers (F202 and DS642P are active or passive types. If they are active then when the 32A ENEL breaker trips so will these two RCDS - so as the electrician said. But....if they are passive types then they should not trip if the ENEL breaker trips.

Now to # I mentioned above. If you have a short black out or brown out there may be such a brief surge in current upwards as the voltage returns or rises that the ENEL breaker is momentarily passing such a high current that it trips the short circuit mechanism - it is electromagentic functionality so fast acting (immediate) for currents from 3 to 5 times 32A or more (whereas the overload is thermal mechanic slow acting). If it trips it will need to be reset. If this is the case you may be able swap it for a less sensitive characteristic - we will discuss this once we know what kind of rcds you have.

 

[pgrbff]

The Enel Arrivo has never tripped to my knowledge.
The F202 to its right supplies the workshop downstairs which is physically disconnected from all machines and lights when it is not in use.
The single switch, Allogio, next supplies the granny flat.
It is only the ds642p and the elletrostop that all switch off together.

With all the mcbs to the right of the ds642p off, when I switch the Enel arrivo off the ds642p does not trip.

 

[marconi]

This indicates that the F202 and ds642p is a passive rcd devices - good.

The fact that the ENEL Arriva C32A does not trip indicates you have not drawn too much prolonged over current through it or had a short circuit - good.

You are back to checking background leakage current, ramp tests of RCDS wiring insulation resistances, testing individual equipments and appliances, connections, etcetera which have been mentioned by others. A competent, methodical electrician with the right test equipment, knowledge and experience and a bit of an Italian Sherlock Holmes in his nature.

Do your neighbours suffer like you or are you 'unusual'?

Had you thought about inviting out someone on the EF to take a look?

 

[marconi]

If I remember correctly some rural Italian single phase supplies do not have an earthed neutral which is why they mandate two pole circuit breakers. A single phase supply is derived from any pair of L1, L2 or L3. Do your electricity poles have three or four wires strung between them?

What you might ask ENEL is for them to move your home from the current two lines to another pair of lines to see if it makes any difference. You might just be connected to a heavily loaded line. You may have to swap again to try all the pairs of lines.

if it is three phase plus neutral (4 wire) you could still ask ENEL to move you to a lighter loaded phase.

Are you convinced you are not drawing more than 20A through the 642P 0800-0900 and in the run up to this period?

 

[pgrbff]

I don't have neighbours, we are at the end of the line. When they replaced the cables 2-3 years ago it was just for us. I'm not even sure if there is anyone else on this "spur". If there are it would only be small residential. I think we are fed directly from a substation and there are 3, I believe aluminium, twisted cables, possibly 80mm(2), but my memory has always been appalling so don't take my word for it.
It is hard to estimate but the line is probably around 2km long. It crosses a valley so is difficult to measure.
From what I understood there are 3 because I have the option of 3 phase and the non-earthed neutral does ring a bell.

 

[marconi]

I am going to let others follow up on whether you might be better off having a three phase supply and what would be required. It has great merit. Over a long distance lower currents in more conductors is beneficial to reduce volt drop and deliver the same power.

 

[marconi]

0800 to 0900.......

You have 2 fridges and a freezer. Are they frost-free?
To be frost free they have a heater controlled by a timer which is either a 24 hr clock with on/off settings or a stopwatch recording how long the compressor has run and after a predefined time turning on the heater.

 

[marconi]

Rather unusually, all your circuit breakers are Type C eg they are marked C20. In the UK, in the domestic setting they would normally be Type B and marked B20 for example. You might want to ask your electrician why this selection has been made and let us know what he says.

Here is an estimate of the volt drop for each amp of current flowing along the supply to your home where 0.33 V/A/km is the resistance per km at 25C of 85m2 aluminium conductor:

2 x 2km x 1 A x 0.33 V/A/km = 1.32 Volts

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So, when you draw say 10A the volt drop is 13V, 20A it is 26V, 30A it is 39V.

Thus if the supply line is energised at say 230V, the voltage at the end of the line will be 230 - 13 - 217V at 10A and 25C ambient. Volt drop will be more in higher ambient temperature.

Items with a motor draw some 5-10 times there normal running current when they start. Your Fluke may be reading very low readings because on the min/max setting the meter captures these brief but large dips in voltage as the motor runs up (on top of any other current being drawn).

 

[marconi]

Is there any socket you can plug temporarily the fridges and freezer in to which is not covered by the ds642P in order to see if the trip stops and moves to another rcd which trips?

 

[pgrbff]

The fridge freezer combo in the area that covers the tripping RCD is not frost free. It is a basic small fridge with freezer above. I do not think there are any sockets not covered by the ds642p that wouldn’t require a 50m extension. Surely there is no time function on such a fridge that would lead the RCD to trip more or less at the same time? Yesterday it did not trip, but the granny flat did. Today it ha not tripped. My feeling is that it is becoming more infrequent.
There are 3 elements that are timed in some way on the ds642p.
A small bronze pump circulating the hot water which comes on for 10 minutes at 06.30 and twice more during the day.
A gardena watering timer that when it operates causes a shallow well pump, less than a year old, to come on for 10 minutes around 06.30.
The solar pump which comes on when the panels reach a preset temp. Usually around 08.30. However I have been present on more tha one occasion when the pump came on without tripping the RCD and the RCD has tripped when there has been insufficient sun to cause the pump to turn on.

 

[marconi]

No a timer is for a frost-free fridge or freezer.

It may not be when equipments turn on that causes the trip but when they turn off. You might want to check the off times for the things you just mentioned.

Is your hob or oven electric? it is a common problem for the electric elements to have earth leakage which can cause rcds to trip. The ds642p supplies your cucina. Might you turn the hob and oven off at its isolator switch when you aren't using them to see if the 0800-0900 aspect of the problem 'goes away'. (I don't want to explain the electrical reasoning just now 'cos I have not the time).

I still think it a good idea (ie. I would do it if I was you) to invite soon an electrician to do the testing and inspection I and others have mentioned because it would rapidly establish the state of your wiring installation and loads connected to it. It also has value in both quality and safety assurance for your peace of mind and your insurers. The Brains Trust which is the EF need some hard information in the form of electrical measurements to consider your problem further. Money well spent. That's my professional opinion - gratis.

I am going out now 1000 UK and will look again after lunch.

 

[pgrbff]

There is no hob or oven beyond the ds642p yet. We currently live in the granny flat. Almost all of the sockets beyond the ds642p are vacant. Bo the timers, watering and water circulation are only on for 10 minutes. Once the solar pump starts it will run all day, but the ds642p has never tripped in the afternoon-evening when the pump would stop.
Given all the problems I have had over the years with the supply, I still can't help think it is the problem.
I am waiting for the electrician to call me. Amongst other things, I'll ask him if he can do some testing.
Can you tell me again what tests@ I'll have to try and work out the translations.

 

[marconi]

I too think you have a poor supply. But first you need to clear your installation of any faults if they exist before remonstrating with ENEL. You may have both installation and supply problems.

DPG - would you advise pgrbff please on I & T, as I see you have been reading the posts. Or someone equally good?

 

[Wilko]

Hi - I know I’m late to the party, so apologies if this has already been covered
1. What type of earthing do you have?
2. Tell us about this solar pump thing you mentioned in the first post. Do you have solar panels? An invertor? Is it attached to your Consumer Unit? If so, I’d disconnect it all and see what happens tomorrow morning .

 

[marconi]

pgrbff: I have more time now and I don't think DPG has seen my post to him.

If you look at Mattg4321 #14 he has listed the important tests and the order in which to do them - the key words to translate are in bold. I will see if I can find some youtube clips you might look at too:

1. Insulation resistance of wiring between L and N, L and E and N and E at 250V and then 500V

2. Ramp testing of the RCDs.

3. With ENEL ARRIVA closed, total earth leakage current measurement using a clamp meter around the incomers and then around the earth conductor to the earth electrode.

and I would add a fourth and fifth

4. Check all connections are tight in consumer unit and kWh meter and do a 'tug' test on all ferrules to check conductors are indeed gripped inside them.

5. Check insulation resistance of appliances both portable and fixed which are normally energised on the circuits protected by the RCDs.