Aftermath of a lightning strike

[Llwyncelyn]

Not sure if this is the correct 'section' in which to post this question?  and in doing so please forgive the ramblings of a dumbo in this regard.

Before the lightning strike last week we had an old EDF black meter with top and bottom readings and two associated boxes one of which we were told controlled the cut-over at 10.30 at night for the preferential tariff and you physically heard the cut-over at both times and in the morning a tank full of hot water.

However after the strike the box which controlled the cut over box was blown to pieces and after a week of EDF Lille Cherbourg and St Lo they finally came out yesterday and replaced the old meter plus the other two boxes with a 'new' re-cycled plastic piece of kit which we were told 'controlled' everything.

Last night no physically noise of the cut over and this morning no hot water.

Please can I post this question of those who are ifinitely more knowledgeable than I?

Is this still an EDF problem or is it one for our electrician.  Whilst my French is just about ok for the what I until know have viewed as the fundamentals of French life it does not extend to this subject.

Please can someone help.

Finally it is some time since I accessed this forum................has it gone quiet and with some well-known contributors no longer being 'seen'

regards

[andyh4]

I am no expert in this field but it occurs to me that if the strike blew your box apart it could well have fried the element in the water heater.  An electrician could confirm this in a minute.

[Llwyncelyn]

Thanks Andy4 it sounds logical.  Will ring the electrician immediately but he is getting a bit fed up with me for he has been out so often in the last week.

thanks

[Anton Redman]

If you had enough of a surge to destroy the EDF part of the box it is possible there is also damage to any or all of the parts that control the hot water cylinder. These are normally called :

 

‘Sectionment Fil Pilote’ and has mains power and earth in at the top and a live feed back to the main EDF box. It is rated at 2 amps so normally also has C2 on the front.

See below for neutral.

 

There is then a normal probably 20 amp disjointer with both live and neutral feeding the ‘Multi 9’

 

The ‘Multi 9’ Takes it’s power from the Disjointer not the normal bar or feed from the connector.  It has an additional neutral input at the top from the Sectioinment Fil Pilote It has additional feed from the EDF box  which has had it’s power delivered by the SFP above. It then has a Live and Neutral feed which go to the Hot Water Cylinder.

 

The front of the Multi 9 should have a small switch with ‘On’ ‘Off’ and ‘Auto’ positions. Try moving the switch to ‘On’ and seeing if the water heats up. Will take an hour or so to make much difference to water temperature but if you have a modern meter you can move it to show current usage and see what happens if you turn the switch on.

 

Broadly unless you would feel secure wiring a Tableau d’Electricite from scratch this is a job for a professional electrician.

[Gluestick]

Lots of confusion about this!

EDF provide a cheap rate between - roughly, varies in different districts - 12.00 midnight and 08.00 AM.

This is controlled by a "Pulse" sent through the mains wiring.

If you contract for cheap rate, your meter is tripped "On" to the cheap rate at night: and "Off" in the morning.

All the power you drawer after the cheap rate kicks in is at the cheap rate! Everything! It is purely a meter function and not a wiring function.

Storage electric water heaters, Chaffe Eau or Ballon,  are wired in through a dedicated pulse switch, which enables (turns on) when cheap rate commences and turns off when it ceases.

Water heaters are thus wired in on a dedicated circuit, controlled by the pulse switch. The heater itself is left switched "On", permanently, but only heats the water once the cheap rate kicks in.

As Anton has already stated, the pulse switch has three positions: Off; On and Pulse. This allows you to override the pulse switch for boost hot water on normal rate.

Perhaps when your electrician is replacing bits as necessary, it might be a good idea to ask him to fit a Parafoudre in the tableau?  This will provide significant protection against lightning strikes on the mains in future.

 

[Chancer]

A simple explanation is needed I fear! As you didn't hear the clunk then your disjoncteur jour/nuit in the tableau did not switch, hence no hot water.

1. Check the switch setting on the disjoncteur, should be set to "automatic" or "auto" , not "arrete"

2. To check the cylinder element is still working (in my experience any lightning strike capable of damaging it would have fried everything else first) switch the disjoncteur to "marche force" or "on", check the water temp after a few hours or just watch the meter spinning around madly!

3. If switch was correctly set and water heats up when switched to override then check wiring to the new EDF box, there should be 2*1.5mm2 cables leading into it, they may have been left out, they carry the "asservissment" (switching) current through the EDF night switching relay contacts.

4. If the wires or cable were in fact leading in to the EDF box then go back to the tableau and try to find the disjoncteur that feeds the asservisement current, on a modern installation it will be the only or one of two 2 ampere ones (usually colour coded pink).

It would help to know how old your tableau installation is.

Good luck

[cheminot]

When this happened to us, as well as the meter being fried, it blew the fuse in the chauffe eau disjoncteur and and wiped out the "disjoncteur heures creuses" which cost about 50 euros to replace.

cheminot

[thetwoofus]

just out of curiosity have you got a lightning conductor,,if not maybe there is a lesson to be learnt  for all of us      [8-)]

[Anton Redman]

You normally need a 'parafoudre' rather than simply a lightening condutor as strike is to EDF wires not your house.

Not that a lightening condutor is not a good idea anyway.

[Jonzjob]

As a matter of interest a lightning conducter is a 'paratonnerre'.

We are seriously thinking about getting one, especially as there so many storms around at the moment.

Has anyone got one or had any experience of one. I know that they work well on buildings like churches and the like... We have read differing oppinions of them. I suppose it's like insurance, i.e. you don't need it until you need it!

We have had a devis from a company called France Paratonnerres and the guy told us that if we had one fitted then we would have to have a filter fitted directly after the main switch. This, I think, is a parafoudra and it covers the power to the complete house. Sounds like a good idea to me?

[powerdesal]

The function of a lightening conductor is to provide a very low resistance path to earth, ie its a preferential path for a strike, rather than using your house and (possibly / probably) doing "mechanical" damage to the fabric of the building.(think earth bar in the sky [:)])

A parafoudre is a different animal, its to protect your domestic electrical circuits from the power surge of a lightening strike affecting the incoming supply and everything connected to that supply.

[Jonzjob]

I can only agree with that lot Steve!!![:D]

[Gluestick]

In fact we were discusing this only very recently.

http://www.completefrance.com/cs/forums/2/966104/ShowPost.aspx#966104

I particularly enjoyed the insurance underwriter's quaint theory about lightning!

[:D]

[bejay]

[quote user="powerdesal"]The function of a lightening conductor is to provide a very low resistance path to earth, ie its a preferential path for a strike, rather than using your house and (possibly / probably) doing "mechanical" damage to the fabric of the building.(think earth bar in the sky [:)])

[/quote]

Sorry but they just don't work like that.

Essentially they generate a charge cloud over the building. This charge cloud has the same polarity as charges present in the thunderclouds. This tends to discourage a lightning strike in that immediate area on the principle that like charges repel each other.

It is a bit counter-intuitive and it really needs a diagram to explain it fully.

bj

[powerdesal]

And the charge is generated how?

A lightening conductor is connected to the mass of earth No? Therefore it is at earth potential.

Conventional lightning rods are connected via a low-resistance

wire or cable to the earth or water below, where the charge may be

safely dissipated. The diversion theory states that the lightning rod

protects a structure purely because it is grounded, and thus a

lightning strike that happens to attach to the protector will be

diverted around the structure and "earthed" through a grounding cable

or conductor.^[4]

There is some uncertainty as to why a lightning strike might

preferentially attach to a lightning protector; the leading assumption

is that the air near the protector becomes ionized and thus conductive

due to the intense electric field. Various manufacturers make these

claims.

[Jonzjob]

http://weathereye.kgan.com/cadet/lightning/bigspark.html  [:D][:)][:D]

[Gluestick]

[quote user="bejay"]

[quote user="powerdesal"]The function of a lightening conductor is to provide a very low resistance path to earth, ie its a preferential path for a strike, rather than using your house and (possibly / probably) doing "mechanical" damage to the fabric of the building.(think earth bar in the sky [:)])

[/quote]

Sorry but they just don't work like that.

Essentially they generate a charge cloud over the building. This charge cloud has the same polarity as charges present in the thunderclouds. This tends to discourage a lightning strike in that immediate area on the principle that like charges repel each other.

It is a bit counter-intuitive and it really needs a diagram to explain it fully.

bj [/quote]

 

No diagram necessary bj!

The traditional Lightning Conductor works by offering a path of least resistance to viable earth.

The effect you are discussing is common in all high energy corona generation: i.e. whilst to the human eye it may appear that a bolt of lightning flashes down to earth from the heavens, the final event is preceded by clouds of positively charged and negatively charged ions migrating both up and down, until a balance of charge is reached, in favour of the cloud. And the flash of energy being disapated is seen as lightning.

In order to better protect important buildings and installations, a Faraday Cage is constructed; which is a metal grid framework which surrounds the building. A car is a good example of a Faraday Cage: which is why they are so safe in a electrical storm. (named after Michael Faraday FRS, who was responsible for many principles of electricity, such as dynamos, electric motors, the principles of EMF, plotting the effect of a magentic field intercepted by a conductor etc.)

Lots on the web for those who don't like sunshine!

http://www.buildingconservation.com/articles/lightning/lightn.htm

 

[trumpet]

I am learning so much, no way am I going out.[geek]

[bejay]

Oh dear.

Steve.   Clearly you are quite correct in saying that once a charge path is created to a lightning conductor then there  is a low resistance earth path formed  which is a far more satisfactory arrangement than the strike finding its way to earth (or from earth)over and through the structure of the building..

But please note what I said in my original post ' tends to discourage' . If this lightning conductor were simply acting as an earth rod in the sky it would be reasonable to assume that any leader in the vicinity would very probably find this path of least resistance every time. It is my understanding that this is not what happens, and indeed would be extremely undesirable.

It is easy to explain this 'discouraging' effect in terms of a displaced negative charge on the conductor but I do have to admit that it is a more contentious theory than I had thought.

At least we are entertaining Trumpet!

bj

 

 

[Ford Anglia]

Further to what's been posted above, I'm sure I remember learning in "O" level physics that lightning conductors are more about AVOIDING a strike than conducting one to earth?

I seem to remember a discussion of the fact that charges like to gather on a point, and when too many gather, the "flow" off the point in what was called an "electric wind". I remeber our physics teacher demonstrating it by holding a piece of bare wire in his hand, while standing on a stool with one hand on the Van de Graaf generator. When he pointed the wire at a candle, it blew the candle flame strongly enough to extinguish it.

He then stood with the wire concealed in his fist, and his hair stood on end. When he raised the wire, however, his hair fell to almost flat, and no-one could get a spark from him. The "electric wind" was dissipating the charge. You could HEAR it, rather like the fizzing noise you often get around high voltage overhead lines in damp conditions.

Since lightning strikes are about DIFFERING charges, I find this explanation makes some sense.

Any comments, anyone? 

[stephen]

I know nothing, and maybe Wikipedia don't either.... but here is what they have to say. Enjoy

http://en.wikipedia.org/wiki/Lightning_conductor

[Gluestick]

Excepting, of course, that Ben Franklin was quite successful at persuading the static charge to run down the kite string into his bottle!

His rather worrying home-brewed lightning conductor seemed to work rather well!

Rather than the reverse.

I believe most authorities are quite open about the perverse nature of static electricity! Similar to blast from major explosives.

The history of RMS (Rendering Mines Safe) for example, is redolent of cases where all that was left was the RMS officer's seaboots, on the one hand: and on the other, the officer was blown through the air and basically unharmed.

Interesting video clip of a guy wearing a Faraday Cage Suit, working live on 500,000 Volt power lines!

http://www.glumbert.com/media/highpower

Edit: And Richard Hammond in a VW Golf being hit with 800,000 "Wolts".

http://gizmodo.com/gadgets/cars/lightning-strikes-car-with-man-in-it-243268.php

 

 

[stephen]

By the way... I had a surge travel to my laptop via the phone line and

modem cable this morning during a nearby strike... very impressive

flash! Miraculously, did not fry my machine (or me)....  Speaks

volumes for the robustness of the Macintosh!

Note to self: must buy a surge protector tomorrow...

[powerdesal]

[quote user="bejay"]

Oh dear.

Steve.   Clearly you are quite correct in saying that once a charge path is created to a lightning conductor then there  is a low resistance earth path formed  which is a far more satisfactory arrangement than the strike finding its way to earth (or from earth)over and through the structure of the building..

But please note what I said in my original post ' tends to discourage' . If this lightning conductor were simply acting as an earth rod in the sky it would be reasonable to assume that any leader in the vicinity would very probably find this path of least resistance every time. It is my understanding that this is not what happens, and indeed would be extremely undesirable.

It is easy to explain this 'discouraging' effect in terms of a displaced negative charge on the conductor but I do have to admit that it is a more contentious theory than I had thought.

At least we are entertaining Trumpet!

bj

 [/quote]

Bj,

I dont disagree with you, I was perhaps being somewhat simplistic in my reply, but I figured that those who know dont want a technical treatise and those who dont know really want a "keep it simple" answer. I try to keep to the KISS principle if at all possible (except at work, where bulls**t baffles brains [8-|] )

[bejay]

[quote user="Ford Anglia"]

Further to what's been posted above, I'm sure I remember learning in "O" level physics that lightning conductors are more about AVOIDING a strike than conducting one to earth?

[/quote]

Yes, this has always been my general-purpose understanding. There is a substantial current flow detectable in lightning conductors in electric storm conditions which does back up this theory. Of course in certain circumstances a direct lightning strike would overwhelm this effect. What has set me back a bit is that Wikipedia (not, I have to say my favourite reference source) really does not have much truck with this idea. If I have understood it correctly the best it can say is that it can't actually be disproved. Grudging or what!

Steve. Thanks for that.

bj