Could my house be badly earthed ?

pthedj

After a recent lightning strike in the village where I live,some of my neighbours in our housing estate & I had various domestic appliances which were affected.The telephones in the area were down after the strike & the broadband filters on my phone sockets & router were charred & destroyed.
More worryingly I've had a portable tv & electrical radiator that no longer power on.These were plugged in at the wall sockets but the switches were off.Also My SKY Box (which was powered on at the time) has stopped receiving the satellite signal & had to be replaced. I also have an internal mobile phone-set which no longer powers on.
A friend suggested that there is no way an indirect lightning strike could destroy so many items if the house was correctly earthed.
Could this be true ? What should I look out for to see if the place is correctly earthed ? Any help would be appreciated.

flyfree

The only way to know for certain if your earthing system is up to standard is to pay a registered contractor to come in and check it.

Your earthing system is directly connected to the ground outside your house through an earth rod and through the ESBs neutralising. This system is then connected to every socket, light etc internally.

The voltage on an lightening strike can be strong enough to travel quite far through the ground as was seen from that "exploding tree" recently.

However the only way to be sure, if you are in doubt, is to get a registered electrician to check out the system, won't cost more than a few euro to do the tests.

fishdog

The only way to know for certain if your earthing system is up to standard is to pay a registered contractor to come in and check it.

+1

Your earthing system is directly connected to the ground outside your house through an earth rod

Exactly. So by having your house properly earthed you have increased the chances of an indirect lightening strike doing damage! This is because the ground around the lightening becomes "live" and conducts. This current can in theory then flow up your earth rod and make sh!t of various sensitive appliences that may be connected to the earth bar and then on to the earth rod by their protective conductors (earth cables).

Having said this, earthing properly is considered the lesser evil.

Cabaal

even if your house is earthed its unfortunately common for ADSL filters and routers to be fried during electrical storms, its good common practice to unplug electrical equipment and phones during lightning storms

pedantic pat

pthedj wrote: »

A friend suggested that there is no way an indirect lightning strike could destroy so many items if the house was correctly earthed.
Could this be true ?

i'm not too sure about this - good earthing would reduce the impedance seen by a surge coming in on your live conductor thus increasing its potential to do damage.most tall buildings , churches etc have a lightning protection system that consists of copper strips that are connected to the an earthing system - maybe this is what your mate is thinking aboutmy advice would be to get some surge protection installed in your distribution board - there are some neat units available now - phoenix do some good ones - http://www.phoenixcontact.ie/products/63.htm

fishdog

most tall buildings , churches etc have a lightning protection system that consists of copper strips that are connected to the an earthing system

That is for protection from direct lightning strikes and great care is taken to ensure that it is not connected to the earthing system of the building. The "earth termenations" (earth rods for lightining protection system) must even kept a minimum distance from the earth rod. This is to reduce the chances of lightining making the entire earthing system live.

It would not be normal for a house to have this type of system.

maybe this is what your mate is thinking aboutmy advice would be to get some surge protection installed in your distribution board

+ 1

Hopr

Some advice from the ESB web site.
http://www.esb.ie/esbnetworks/safety_environment/equipment_protection.jsp
Cheers
Hopr

pedantic pat

fishdog wrote: »

That is for protection from direct lightning strikes and great care is taken to ensure that it is not connected to the earthing system of the building. The "earth termenations" (earth rods for lightining protection system) must even kept a minimum distance from the earth rod. This is to reduce the chances of lightining making the entire earthing system live.

I don't think this is the case fishdog - the relevant EN and BS guidelines say you should connect the lightning conductor to all metallic pipes and structural steel etc to avoid the risk of flashover from the lightning conductor - i seem to recall seeing a diagram showing the lightning conductor bonded to the MET in order to achieve this.

davelerave

yes i also think that the 'down' conductors from a lightning rod and structural metalwork /grounds are all interconnected in general to prevent flashovers and fires

irishspark

I saw the same problem in a customers house years before and nowadays with so much technology in a house it can be a nightmare to unplug everything in a storm.

i installed a TVSS in my house. really easy to install and goes right beside the fuseboard. you'll pick up a single phase one for bout 300 quid. anyone that supplied UPS systems stock them. all u need then is a half decent sparks to install it!

davelerave

irishspark wrote: »

I saw the same problem in a customers house years before and nowadays with so much technology in a house it can be a nightmare to unplug everything in a storm.

i installed a TVSS in my house. really easy to install and goes right beside the fuseboard. you'll pick up a single phase one for bout 300 quid. anyone that supplied UPS systems stock them. all u need then is a half decent sparks to install it!

and check the earthrod

pthedj

Thanks for the input guys

fishdog

pedantic pat:

I don't think this is the case fishdog

I looked it up to try to find a reference to prove you wrong, but you are correct!