Lightening Surge Protection

[Lightening]

I live in Pembrokeshire, Wales and twice had equipment damaged through a lightening strike on the copper telephone lines feeding my house which passed through my router and ethernet network. At the present time I only get 8 Mbps from the internet and have since introduced a wi-fi bridge between my router and an adjacent tp-link TL-WA901N 450 Mbps Access Point router. This works fine with minimal speed loss but we are soon to receive a fibre-optic cable connection with a choice of 100, 330 or 1Gbps speed. Any advice in selecting a new Wi-fi Range extender/router or any other comments will be appreciated.

Robert

 

[OzarkEdge]

I live in Pembrokeshire, Wales and twice had equipment damaged through a lightening strike on the copper telephone lines feeding my house which passed through my router and ethernet network. At the present time I only get 8 Mbps from the internet and have since introduced a wi-fi bridge between my router and an adjacent tp-link TL-WA901N 450 Mbps Access Point router. This works fine with minimal speed loss but we are soon to receive a fibre-optic cable connection with a choice of 100, 330 or 1Gbps speed. Any advice in selecting a new Wi-fi Range extender/router or any other comments will be appreciated.

Robert

The incoming twisted-pair telephone service should have safety Earth ground shunt protection to route major stuff to ground, not into the house. Make sure all phone and power ground connections are intact.

A phone line surge protector inside the house might help block minor stuff from reaching specific telephone equipment.

Fiber service should stop electrical power disturbances from coming into the house.

If you subscribe all the way to 1 Gbps service, you may want to reconsider your entire network plan to best utilize your new service and meet your needs. Otherwise, install the 100 Mbps service and see if your existing network is good enough for now.

OE

 

[degrub]

another way lightening can impact is when the earth's potential is shifted before the current reaches the earth. This changes the ground potential that all electrical circuits are tied to. Sometimes the damage is from the ground side of the circuit in a reversal of current flow. We see this commonly on the US Gulf coast. If the electrical circuits are not properly tied to a common earthing point/grid, then potential differences exist and current will flow, sometimes destroying equipment. a weak point can occur if there is significant corrosion at the earthing connector and high resistance. The NEC code for antennas was changed so that secondary earthing points cannot be used and the bonding cable must have minimum turns ( if any) to the structure earthing point. The antenna down link cable lightning diversion conductor is supposed to be tied to the structure electrical earthing point. Also, the sheet current from the strike will travel across surfaces. Any resistance in the path can cause arching and damage as well.

Yeah, phone cable doesn't conduct much current before it vapourizes. The current can travel down the outside of the cable as well as sheet flow.

Whole structure lighting arrest (sacrificial little box) is an inexpensive way to reduce, but not eliminate the risk of damage. Just replace when the indicator goes out or if the structure sees a hit.

 

[Lightening]

Thank you OE, I can see no earthing to the present copper line and at the time I contacted the telecom company BT, but they took no interest in the problem and that's why I thought it best to set up my own bridge system even if the first router is sacrificed in the strike. The new Fibre system will be strung on poles from the village exchange and I have read that the steel strengthening strands in the cable can still work as a conductor. A question I have on using a wi-fi bridge is how much speed I am likely loose between the first and second routers and therefore how many extra Mbps should be built in eg if I go for a 330 Mbps system will two routers listed for instance 5GHz , 1300Mbps transfer the data without loss?

 

[degrub]

The lightning protection is on the wooden pole carrying the line, usually including the electrical distribution. You may see a small ariel above the tip of the pole or more commonly, a third bare wire running from pole to pole across the top along with the power conductors below that. There is a cable that runs from the top of each pole to a coil of bare wire under the bottom end of the pole. There are also "line fuses" that will open on high current surge on the power lines. The electrical drop to the house meter and panel will provide another path to earth through the house earthing point.

 

[Lightening]

Thank you degrub, I will do some scouting. The last time it happened there was some distant thunder and suddenly a bright blue flash on my BT Hub. Later I found that the surge must of continued down one of the ethernet branches and wrote off my Tesla Powewall Gateway. Although I am sure it is not allowed, if a yellow/green earth cable was connected to an electrical plug and placed in a socket, this would provide an earth.

 

[degrub]

The elevation of ground voltage (equal but opposite charge polarity to what is in the cloud) during/before a strike can do the similar damage to electronics. Just before a strike, there are multiple up-leaders from the earth that are trying to meet the downward moving current ( lightning bolt). One or more will succeed. You can find U-Tube videos of the phenomena.

Lightening can strike from clouds tens of miles away, but that is relatively rare. Most are closer.

Surge protectors use MOVs or avalance diodes or other techniques between Load and Neutral, Load and Ground, Neutral and Ground to absorb as much energy as they can from the potential differences that occur.. In the UK, your system would be different but similar.

 

[degrub]

here is a link that explains this more concisely -

https://m.littelfuse.com/~/media/electronics/design_guides/varistors/littelfuse_led_lighting_spd_module_design_and_installation_guide.pdf.pdf

 

[Lightening]

A very good link, thank you. I now have a much better understanding on how electrical surges are formed and enter the home.