How To Protect ADSL Connected PCs From Lightning
Use WiFi to Isolate Home Computers From Storm Strikes on Phone Wires
Aug 14, 2009
Electrical storms and lightning strikes are a fact of life in some regions. Unfortunately, lightning can strike overhead fed phone wires which are common in rural areas. The phone company usually put gas-discharge tubes into the network termination equipment, but a direct strike on the phone line will often still send a damaging surge through the ADSL modem.
With luck it will be just the modem that is damaged, but the surge can pass to the home network via Ethernet cables, damaging network cards or PC motherboards, leading to potential loss of data.
Avoid Electrical Storm Damage to ADSL PCs by Connecting to The ADSL Modem Via WiFi
Ethernet connected home networks are often connected directly to the ADSL modem Ethernet ports. ADSL modems with integrated WiFi connectivity are readily available, offering a handy way to connect laptop PCs to the Internet. If all the home PCs need to do is connect to the Internet and share printers rather than exchanging large amounts of data, an easy way to get electrical separation from the ADSL modem is to disconnect the Ethernet connections and fit the PCs with USB WiFi adapters.
WiFi is not as fast as a 100-baseT Ethernet network, though it is plenty for streaming audio MP3s. Even 54Mbps WiFi is not as fast as an equivalent speed switched Ethernet network, and households that move a lot of data about, such as DV video files will balk at the loss of speed.
Such users can still achieve isolation from the ADSL modem by using a WiFi access point connected to an Ethernet switch to carry data to the Internet.
Minimize Lightning Damage by Reducing the Phone Wiring and Physical Cable Separation
Simply connecting to the ADSL modem via WiFi is a good start but care is still needed with the installation. The WiFi ADSL modem should be placed close to where the phone wire comes into the house - this is good for ADSL speeds too. If possible the internal phone extension wiring should be disconnected - use DECT wireless phones or similar cordless phones. If it cannot be disconnected it is essential that Ethernet wiring and electrical wiring is kept some distance (1m or 3ft) away from the phone wiring. Often Ethernet and phone wiring is run in parallel runs or the same channel, which is bad for induced surges.
The likelihood of lightning damage to a computer can be reduced, particularly in rural areas which frequently have long runs of overhead wiring by connecting to the modem via WiFi. This will not eliminate the risk of lightning damage as electrical storms can also hit the electrical power distribution network and introduce surges that way. However, the risk is greatly reduced if strikes on the phone network can be kept out of the computer network. Though the ADSL modem itself may still suffer damage, this is much better than lightning damage to the PCs on the home network and the associated potential data loss.
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