Lightning Strikes

[stilljustbrowsing]

On aircraft, the maximum is 0.2ohms for the bonding cables, but the system only prevents static build up to prevent electrical interference with the radio equipment. If the aircraft gets hit by lightening, there is an entry point and an exit point, the damage can be quite sygnificant BTW!
When I left England 7 yeas ago, it was still RCCB's that were required in houses.

[Ian]

Prommee, SJB, Thai electricians are incredible, as you say joints are just twisted and taped, wiring is surface with aluminium collar ties, junction boxes non existent, primitive screw in fuses, if there is a trip it is an old ELCB of such a size its response time must be in seconds rather than milliseconds.
In my time I have rewired and modernised old Victorian houses and factories in London, but never seen anything as primitive as this.
When I rebuilt and modernised my house, plus adding two rooms, the builder wanted to use his regular electrician, I watched him for an hour then said get rid of him I'll do it myself.
Funny thing is most plumbers I have watched seem to be good at their job, I wonder why this difference?

[stilljustbrowsing]

If I recall correctly, the old fuses were set to a minimum rating rather than a maximum rating. I think that in itself is quite scary.
Volts jolts, amps kills!

[stilljustbrowsing]

Thanks for the forum direction! (and of course your other relevant advise regarding the topic)
Wiggly amps (ac) has always given me a head-ache, but there is very little difference between DC electrics and hydraulic systems.

[Ian]

My earth system is a single 4mm wire connected to a buried metal plate, it is adequate for me as I do not use ELCB protection but prefer RCCB. As far as I know all new installations in the UK have to be RCCB as the electricity suppliers no longer supply a company earth. Perhaps Noaksy can confirm, I am about 25 years out of the business.

Hi Ian,
Re: RCCB, I'm also many years out of the business but the 'bible' of electrical installation is the IEE Wiring Regulations. I believe the latest edition is the seventeenth edition. Here's a link: http://www.theiet.org/publishing/wiring-regulations/
If you're interested you can buy a copy from Amazon.co.uk, and there's also a home study course available.

I suppose we should be asking if there is a Thai equivalent to the IEE regs or if there are any regulations at all we should be following. Does anybody know?

Regarding electricity suppliers no longer supplying 'a company earth': I'm not sure what you mean by a company earth but if you mean electricity supply companies in the UK don't supply an earth at all to consumers, I'd be very surprised.

Finally, forum fiends of an engineering persuasion might enjoy the forums at eng-tips.com

In London the domestic supply was by underground armoured cable, the armour was bonded and earthed at the substation. Hence in the domestic insulation this armour could and was used as the main earthing point for the house and was loosly called a Company Earth.
As the result of several successful damage actions where this "earth" failed, electricity supplier no longer undertake to provide "earths' for consumers, thus although such earths still exist the supplier accepts no liability if you use them.
In rural areas, such as where I live, supplies are overhead and consumers have always has to provide their own earth, the supply is just a two wire live and neutral. Before the advent of ELCBs and RCCBs, the supplier would test the consumer's earth to ensure it was adequate. This was also cover in the Building Regulations.

Note that electricity suppliers are now only responsible for installations up to the service meter, all subsequent wiring etc is the responsibility of the consumer, in most cases a local electrical contractor. This contractor will fit and supply an earth point but of course it is not free it will be included in the installation costs. Incidentally with the increasing use, invariably with new buildings, of plastic water pipes, it is no longer acceptable to use a copper waterpipe as an earth.

Note also that whilst the supplier has a duty to check all wiring before connecting a supply, in normal practice the inspection is contracted out locally, often to the company doing the installation

Your question as to the Thai equivalent sent me on a long search
I found this:
hai Industrial Standards Institute (TISI)
(Standards Information Centre)
Rama VI Street,
Bangkok 10400
THAILAND Tel: (66 2) 202-3512
Fax: (66 2) 247-8734
E-mail: thaistan@tisi.go.th
stdinfo@tisi.go.th

and this:
Thai Electrical & Mechanical Contractors Association
216/6 7th Floor LPN Tower Nanglinchee Road Chongnonsi Yannawa
Bangkok, Thailand 10120
Contact : 662-2854287 662-2854546
Fax : 662-2854288

After reading many forum posts on this topic it seems there are no regulations, however several firms will offer work to BS7671 standards, This is the IEE one you are familiar with.

Perhaps as a service to Farangs we should draw up a list of what to do, what to avoid, and what to replace if you want your Thai home electrically safe

[prommee_NE]

Perhaps as a service to Farangs we should draw up a list of what to do, what to avoid, and what to replace if you want your Thai home electrically safe

Good idea Ian...do you want to raise a new topic?... or I could simply add a bit to the heading of this topic.

Noaksy...thanks for the link.

SJB...I thought 0.2 Ohm was the internal aircraft bonding requirement...for external earth connection, the requirement is 1 Ohm for normal but not to exceed 10 Ohms under abnormal circumstances...and 25 Ohms if you are a Harrier under the trees.

Edited cos I put 0.2V instead of 0.2Ohm

[stilljustbrowsing]

Promee, yep, that's right, so far as I know. Just remember, electricity, water, and politicians have one thing in common...........THEY ALL FOLLOW THE PATH OF LEAST RESISTANCE! (sorry Ian, I really had a resistance failure!)