Rcd Tripping During Electrical Storms

[kokesaat]

Our house has a F&G 0.03A RCD (F7-40/2/003) that sometimes trips during big electrical storms near our home. Of course, when that happens all the power goes off in the house. If we're at home, it's annoying, but simple enough to reset, usually waiting for the worst of the storm to pass. But if we're not at home, our refrigerator loses power and that's not good if for more than a few hours. The main circuit breaker doesn't trip, only the RCD does.

Prior to this electrical arrangement, we didn't have an RCD and the main circuit would occasionally trip during a storm. We ??upgraded?? our electrical circuits a few years ago, and I was hoping the RCD would add an element of safety as well as get rid of the tripping problem. Not so.

We do not appear to have any other electrical issues in our house....as far as we can tell, everything works as advertised.

Can any of our electrical experts provide some suggestions that might help isolate or correct this problem? All ideas welcome.

[InterestedObserver]

You are going to need a megger to test the insulation resistance of all your electrical wiring to earth. Electrical surges during storms often will cause leakage currents and trip circuit protective devices. If it is a persistent problem then you may need surge suppressors before the RCD/Main Breaker.

[haveaniceday]

I have the same issue in the current rental.

I installed a safety switch on the inbound cables just before the main circuit breaker distribution box. The storm can be a couple of KM a way and it will trip when selected to 5.

It has a dial with 5,10,15,20 & Direct.

When I go away for a couple of days, I select DIRECT and I also turn off the water pump main CB and leave a Idiot note to remind me near the front door and on the fridge for my arrival !!!

This house is not earthed.

I have earthed the hot water shower heaters and the water pump only.

I will point out, I have never had a electrical supply so dodgy as this one though in Thailand. A few weeks ago we logged the outs, averaged 6.5 a day to all the homes, and I got many more of course and many brown outs with lights dimming etc.

The AC are the landlords, you can hear them struggle in the brown outs before I kick them off. The fridges and comp, TV, I have on many UPS's, so at least they have a steady supply.

I hope you get an answer, will help with next home that will be a western standards job.

[Crossy]

Nothing unusual about your RCD occasionally tripping during storms, ours does. It is after all intended to see imbalances in the electrical supply.

Do perform an insulation test if you have the kit, but unless the RCD is tripping during normal operation I would not be overly worried.

As IO suggests, a whole-house surge arresting system may help, but it's not a cheap solution.

If you have a fridge or freezer consider wiring a special circuit with it's own MCB on the un-protected side of the RCD, like the split-service diagram on this page http://www.crossy.co.uk/wiring/Consumer.html

[electau]

It should be remembered that RCDs must trip between 50% and 100% of the rated trip current, They must not trip at 50%. RCDs generally will trip at about 70% in about 20mS.

If you have a RCD that has 5/10/15/20mA settings, you should take this in to consideration.

Max standing leakage current should not exceed 30% of the rated setting in mA.

And a note on supply failures and low voltage. These are often occur on the HV network, failures can be caused by lightning which trip autorecloser switches which lock out after 2 operations and have to be reset and closed manually. The low voltage can be caused by demand on the system in peak periods on the HV network.

　

Edited August 18, 2011 by electau

[electau]

In reply to post #3.

You will not get a "western" electrical supply until the PEA upgrades its HV and LV network, and that is not likely to occur in the near future.

All you can do is to make sure that your electrical installation complies with the minimum voltage drop requirements with regard to the consumers mains.

It would be recommended that you fit manual reset no-volt relays to each of your airconditioners, they will drop off line when you do get periods of low voltage.