RCD trips every morning between 08.00 and 09.00

[pgrbff]

I live in rural Italy. You get to chose your max KW here and pay accordingly. Most home have 1.5-3.0 kw, I pay extra for 5kw. I am at the end of the low voltage lines, one of only a few on this circuit. I constantly have voltage problems, according to my fluke multimeter it can go from 190v to 234v over a few minutes without me changing the loads at home. Every time you switch something on you can here it from either the bathroom fan, cooker fan or oven fan slowing down or speeding up.
My main problem is that the RCD often trips, picture attached. Currently it is tripping nearly every morning between 8am and 9am. There are currently no devices on time clocks. I thought it might be the solar pump coming on but it isn’t. It trips when there is no sun and the pump is off.
I was considering installing a “restart” RCD but would be interested to know what you think. My electrician, although quite good does little more than shrug his shoulders.

 

[Lister1987]

Central heating? Time clock firing immersion on? Thermostat firing immersion on temperature drop?

 

[pgrbff]

The 3 central switches all go together.

Central heating? Time clock firing immersion on? Thermostat firing immersion on temperature drop?

Central heating? Time clock firing immersion on? Thermostat firing immersion on temperature drop?

No central heating or hot water other than solar. Solar not on clock. Pump kicks in when panels hot enough. Have stood and watched temp go up and pumps kick in without causing rcd to trip. Rcd has also tripped on days when too cloudy for solar pump to fire.
No immersion, gas boiler also off as not needed. Time is also not always exactly the same, just between 8am and 9am, never at any other time of day

 

[DPG]

Do any of your neighbours have something that switches on at these times?

 

[pgrbff]

I'm not even sure if there are any other properties on these lines, but it is perfectly possible. I assume a restart RCD would solve the problem? How do I determine if it is 2 or 4 pole?
The unit on the right is an RCD, what is the two gang switch on the left? Justa an MCB?
The wiring here is very different to the UK.

 

[static zap]

Thoughts try narrowing it down to the 3 central switches , as "a way in" for mystery current , by leaving one /or /other off and see if still trips.
(also watch supply volts-)
----Dafter thoughts---
One piece of equipment may be clever and shut down if volts are too low...Messily.
Any security ,daylight sensitive lights turning off ?

 

[GBDamo]

Whats on the C20 breaker?

If you can leave it off and see if RCD still trips.

Could be compression fault, as the sun comes up and the building expands, a cable somewhere is pinched and trips causing both on earth and short circuit fault.

 

[Toneyz]

I went to a house that had the same problem every morning the RCD tripped it turned out that every morning her husband had a shower in the master ensuite and water was finding its way past the tray seal through the joint in the floorboards and into the garage batton holder.

 

[Des 56]

Link to a previous discussion
This

 

[pgrbff]

I went to a house that had the same problem every morning the RCD tripped it turned out that every morning her husband had a shower in the master ensuite and water was finding its way past the tray seal through the joint in the floorboards and into the garage batton holder.

Wiring in Italy is all in conduits. As you build/rebuild walls are chased and conduits installed. 99.9% of floors are solid so conduits are laid before floor is poured. When the general building work is finished the electricians use a fish to pull the wiring which is always stranded here, through the conduits. If the distances are long you have to install larger intermediate boxes throughout the building.

 

[pgrbff]

As much as I would like to discover what is causing it, and I will continue to look, I need a solution soon. If I go out for the day, leaving before 8am, I’m likely to come home to a defrosted fridge and freezer.
The house wiring is divided into two, this is the main board, there is a granny flat which has its own distribution board. The RCD in the granny flat has been tripping randomnly for years, we have never discovered the reason.
The overhead low voltage cables to the house were replaced three years ago. Many houses here still only have 1.5kW supplies, the lines could not cope with my 5kW. I complained about low voltage, they made me pay for a device to be installed to monitor V for 10 days, and then replaced them. I still get very low voltages and have regular short power cuts.
This problem is relatively new and fairly consistant. Nearly every day.
I would like to buy a restart RCD but I’m not sure what to buy.

 

[marconi]

Some thoughts:

1. You have a 5kW supply. At 230V this is a current of 5000/230 = 22A.
2. Your Main disconnector - ABB ds642p - has three protective current detetction functions in one device - short circuit, prolonged over current and residual current through 'earth leakage'.
3. The short circuit function is obvious - could there be an intermittent short circuit i your home? If there was then other mcbs would likely operate - are there?
4. Prolonged over current. To protect wiring and not draw more than 5kW for 'too long' there is thermal device in ds642P which heats up and eventually will trip the disconnector. Might you be drawing more than its rating which is 20A during 0800-0900? As I said at (1) if your load is 5kW or more then the current flowing is 22A or more. Normally a 20A mcb would stay closed for a constant 20A. For an over current of 13%, ie: 1.13 x 20A =22.6A it is designed to not trip within an hour but could/will do after an hour has an elapsed. For an overcurrent of 45% ie: 1.45 x 20 = 29A it must trip within an hour. 22.6A and 29A are at 230V power consumptions of 5.2kW and 6.7kW. Might you be overloading your supply and the disconnector unknowingly?
5. Earth leakage is a fact of wiring and electricians and appliance makers try to keep it low. But when many things are energised and/or if wiring is not in its prime or been installed well, earth leakage can accumulate and be a high standing current. Although it says 30mA difference to trip the disconnector, a standing current of say 20mA has meant the earth leakage trip is operating within 10mA of its must operate threshold. For some earth leakage trip a lower current passing for longer will cause them to trip. You could asl your electrician to d a ramp test on the earth leakage detection function of the disconnector to discover if it is simply over sensitive or operating close to the threshold of tripping. Some electricians have a sensitive ammeter which will measure earth leakage by measuring the difference current in the two incoming lines or passing down the earth conductor. A way to overcome tripping due to accumulated earth leakage is to dispense with a single residual current detector(rcds) 'up front' and to protect sub sets of final circuits by two ore more rcds or to protect each final circuit with its own combined residual current breaker and overcurrent (rcbo) in lieu of the separate circuit breakers you have now.
6. Last, for now, some rcds are active types which means they trip when the electricity supply is lost or dips below a threshold. Your disconnector is designed to function normally for UT 125-230V - if an active type it may trip when the voltage drops below a threshold (125V?) Other rcds are passive types and don't respond to a loss of supply - I cannot quickly find out what type your disconnector is - do you have to reset it when you have a full blown power cut?
7. Ok, not quite the last - the disconnector may be suffering from old age or previous high current trips which can make it lazy and more sensitive. Loose/poor connections before or after the disconnector can also cause trouble to residual current detectors and so are worth checking thoroughly or remaking. And by connections that is all of them including where breakers connect to busbars and in/out of meters and intakes.

Hope this helps you a little. I would not support an auto remake disconnector. That would be an unsafe bodge.

Please keep us posted on progress if you would.

 

[static zap]

My thoughts were with @marconi No 6
(or a feature of outage triggering RCD)
Based on probable peak activity of others !
..No 4 is another of my plausible favourites.

 

[mattg4321]

Any insulation resistance testing been done? Ramp testing of the RCD? Earth leakage clamp meter?

I would do those tests in that order.

 

[marconi]

When my auntie lived in a farming hamlet near Aquino, she and her neighbours 'knew' the local electricity supply had its limitations. My British auntie had to learn to be more careful about what she used and when, and co-operate with neighbours to deconflict and spread out their heavier loads. No-one wanted to be the person who caused everyone nearby to be plunged in to darkness! Not a bit like the way be British do things without any real care for what, when and how much load we turn on. Her supply capacity was 25A but would not dream (nor would her neighbours) of using all that.

My auntie had a tariff that was dirt cheap 1900 to 0700 each week day and all weekend to encourage off peak usage. So for example she turned on the 1kW(!) over bath immersion heater when she went to bed and her washing machine at 6am when she got up.

As an extra, when I visited her with my father I had a butchers at the 'update' a local electrician had done. I found he had dug and installed the earth electrode, but forgotten to come back and run the cable between it and the CU. No mandatory testing and certificates. To be fair, this is not a story against Italian electricians - he knew it was required - the poor chap's wife was diagnosed with breast cancer and this meant travelling a very long way to the hospital (Gemelli in Rome) where she had her successful treatment - and at the same time work and look after their 3 junior school children and her mum(84 partially sighted) and dad(86 dementia) in the same home. He was exhausted by it all. He returned to do the work and invited my Aunt round for dinner to celebrate his wife's homecoming. Make sure you nag your wife to check her -----!

I have Italian blood so have a great fondness for Italy.