RCD trips every morning between 08.00 and 09.00

[Bobster]

Powerwall | Tesla

Powerwall is a home battery designed to store energy from solar or the grid, so you can use it anytime you want—at night or during an outage.

www.tesla.com

Maybe this would be something to look into?

No personal experience with the product, but in principle should work well for you.

Clearly cost/payback analysis would need to be done, an I'm sure other manufacturers make similar solutions.

There maybe members that have installed or have first hand knowledge with these systems.

-

Regarding your RCD issue, a good electrician should be able to rule out your fixed wiring pretty quickly against it being a problem.

Once this has been ruled out, an auto re closing RCD maybe the most cost effective solution, if the issue is with your provider.

 

[marconi]

Could you list the equipment which is permanently plugged-in and ready for use, including items such as the washing machine even if the on/off switch or programmer is set to off? Do you have any interference filter socket strips or surge suppression socket strips plugged in. IT equipment?

 

[marconi]

Could you measure the voltages L-N, L-E and N-E at the input to the Arriva ENEL Disconnector (top left) when the Disconnector is open and then immediately afterwards closed? It would be helpful if you could do this on a number of occasions over a few days.

 

[HappyHippyDad]

I would just pay for Marconi to fly out to you. Cook him some nice meals and splash out on a fancy bottle of wine and your problem will be solved!

 

[pgrbff]

Could you measure the voltages L-N, L-E and N-E at the input to the Arriva ENEL Disconnector (top left) when the Disconnector is open and then immediately afterwards closed? It would be helpful if you could do this on a number of occasions over a few days.

I'm off to Venice tomorrow morning, my dad is having his hip replaced and he is 85, mum has dementia so not sure exactly when I'll be back. That is why I was looking at the restart RCBO. One of the RCDs is bound to trip whilst I'm away. I will definitely do when I'm back.

 

[marconi]

Happyhippydad - no pressure then!

One of the things I am thinking is happening is that the supply is IT ie: the N is not earthed anywhere so effectively the supply is L1 and L2 both at a phase voltage wrt to 'earth'.

Stray capacitive effects will be at play causing earth leakage currents, often much higher when there are dramatic voltage variations as he experiences.

You know that for TN and TT it is wise to ensure the deltaIn is 30% of the design deltaIn because for a steady 50% of design deltaIn (ie 15mA for 30mA RCD) it will operate and open.

This limit is much lower for an IT system for reasons I will not go into now. The wise maximum leakage current to minimise nuisance trips through capacitive currents is 17% of deltaIn so 0.17 x 30 = 5.1mA! - so you can see the RCD may be on the edge.

HHD - so why did I suggest the voltage measurements in my recent message?

 

[pgrbff]

Powerwall | Tesla

Powerwall is a home battery designed to store energy from solar or the grid, so you can use it anytime you want—at night or during an outage.

www.tesla.com

Maybe this would be something to look into?

No personal experience with the product, but in principle should work well for you.

Clearly cost/payback analysis would need to be done, an I'm sure other manufacturers make similar solutions.

There maybe members that have installed or have first hand knowledge with these systems.

-

Regarding your RCD issue, a good electrician should be able to rule out your fixed wiring pretty quickly against it being a problem.

Once this has been ruled out, an auto re closing RCD maybe the most cost effective solution, if the issue is with your provider.

I'd heard about the reliability of Tesla, but also the cost. Not sure if I'd get my money back, even over 10 years. Nice idea, I'm afraid I can't afford it.
I have ordered two restart RCBO's, not because I can't be bothered to find the cause, but after 3 or more years I need to know I can go away for a couple of days without worrying too much.

 

[pgrbff]

Happyhippydad - no pressure then!

One of the things I am thinking is happening is that the supply is IT ie: the N is not earthed anywhere so effectively the supply is L1 and L2 both at a phase voltage wrt to 'earth'.

Stray capacitive effects will be at play causing earth leakage currents, often much higher when there are dramatic voltage variations as he experiences.

You know that for TN and TT it is wise to ensure the deltaIn is 30% of the design deltaIn because for a steady 50% of design deltaIn (ie 15mA for 30mA RCD) it will operate and open.

This limit is much lower for an IT system for reasons I will not go into now. The wise maximum leakage current to minimise nuisance trips through capacitive currents is 17% of deltaIn so 0.17 x 30 = 5.1mA! - so you can see the RCD may be on the edge.

Didn't understand any of that. But I think you are sort of confirming, without me convincing my helpful and professional, but very Italian electrician, to undergo all the testing, that it is probably a supply problem.
I have very little knowledge, I'm far from academic, but I do think I have more than my fair share of common sense. The utter random nature of what has been happening has 99% convinced me already that this is not something in the house.

 

[pgrbff]

In a couple of days it will be August, and in August everything shuts down in Italy.

 

[Bobster]

Didn't understand any of that. But I think you are sort of confirming, without me convincing my helpful and professional, but very Italian electrician, to undergo all the testing, that it is probably a supply problem.
I have very little knowledge, I'm far from academic, but I do think I have more than my fair share of common sense. The utter random nature of what has been happening has 99% convinced me already that this is not something in the house.

The good thing is though (or unfortunate for you currently) is that it isn't entirely random as you state, but at a fairly specific time of day.

If you cover my costs to Italy, I'll happily get to the bottom of it for you.

On a serious note, an electrician with some test gear should prove your fixed wiring and most appliances that are permanently powered in a couple of hours.

You want them to be testing at a minimum, the insulation values of effected circuits, cumulative earth leakage, RCD tests including ramping the RCD and then to PAT test the appliances. (It's not called PAT testing anymore, but everyone knows this terminology, unsure of the equivalent name in Italy).

 

[marconi]

I think you have two problems:

1. The nuisance RCD tripping;

2. A supply problem by which I mean everything owned by ENEL up to the input terminals of the ENEL Arriva disconnector.

For (1) I believe there is an interaction between the supply problem and the electrical characteristics of your wiring and the loads connected which is causing transient 'differential currents' of sufficient size to trip the RCD. I think these transient differential currents are more significant because you have an unearthed mains supply unlike say in the UK where the neutral is connected to earth. I reckon you also have a 'weak' earth which means that electrical noise can be introduced into the wiring and loads via the green/yellow earth conductor. It is is starkly apparent when there is a trip because all your circuits are protected by one RCD per dwelling - bad practice. In my home the circuits are spread over 4 RCDS and one RCBO. The cheapest minimum is two RCDs per dwelling. There are also RCDs which are less sensitive to transient effects which cause nuisance tripping and which have a higher standing threshold current at which they trip (between 0.7 and 1 x deltaIn).

For (2) I believe there may be a joint fault, an insulation fault, or someone also connected on occasion drawing a large current and consequent volt drop. It is also a tall order for such a long feed to supply up to 5kW to your home when the energising voltage at the transformer end is circa 230V - Ohms law and volt drop effect. There is also the significant transient surge in current when motors start say in your fridge or water pump which will cause a brief but noticeable volt drop.

Last, the wiring technique of running many conductors together in conduit around the house increases capacitive linkage between them and the possibility of induced currents ; some of which might cause earth leakage currents or differential currents detected by the RCD. Any filters commonly found in white goods, computers, also 'dump' transient and steady currents to earth which the RCD 'sees' as a differential current. The threshold for nuisance effects is lower for an I-T earthing system which I reckon you have.

What you can buy are RCDs which are less sensitive to noise and disturbances - but I think the best solution is to spread your final circuits over a number of RCDs or even better an RCBo for each final circuit. If you did the latter it becomes very obvious which circuit or load is the offender in the event of a fault or nuisance trip and the whole house is not blacked out.

Even new wiring in good condition can have minor faults which can over time cause trouble - hence on completion and then regular inspection and testing.

You either make your installation more resilient to electrical disturbances or you isolate it from the mains supply using the battery, charger, inverter idea for which the mains supply then simply charges the battery and the battery powers the site through the inverter.

Or, (3) you opt for a three phase supply or (4) ENEL install a high voltage line to your home and only then transform down to 230V. With (4) you could have a decent local earth which enables also a neutral.

 

[marconi]

Pgrbff - hello again. I wondered if your trip problem had been fixed?

 

[pgrbff]

I bought the two restart RCBOs but August is only just over, and a month when Italy shutsdown completely. I am away still looking after my elderly parents. I leave a light on at home and an elderly couple some 3km away check every night to see if I still have power. Neither board has tripped for over a month, but this is not unusual, the problem is completely randomn and could return at any time. This is why I am convinced that it is with the supply rather than home. My electrician only returned to work at the end of August and I will ask him to fit the two restart RCBOs. He has always said I should complain to Enel who look after the supply and I probably will when I return home. Thank you for your interest, I wish I could tell you more.

 

[marconi]

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