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14.  Boom! Zap! Lightning Strikes and Voltage Spikes  7/5/12 by Dave Immer

If your ISDN line delivers a lightning-induced voltage spike to your codec, a few things might happen:
1. An easily replaceable fuse gets blown.
2. The software and programming get corrupted requiring a factory reset (cold boot.)
3. A major component gets fried, requiring factory service or replacement.

In addition to your AC-power lines, your ISDN line is vulnerable to lightning strikes and should pass through a surge protector before connecting to your valuable equipment.  Many people think that just using an AC-power surge protector is enough. But it’s the ISDN line itself that I’ve found to present a higher risk of damage.

A basic surge protector that includes phone or ethernet jacks will cost in the $50-$80 range and is worth it. They are available at hardware stores, Home Depot, etc. For a more robust system, check out . I use the Tower Max CO/4-110 (this replaces the RJ-45 wall jack) and Tower Max 4 KSU for my lines.

The surge protection device will “sacrifice” itself should a strong enough voltage event occur. You will have to then replace the device – a bargain compared to replacing your codec. If your line seems to be dead, this event may have occurred. Test your line by plugging it directly in to the wall jack. If it works then that’s what happened.

If you don’t have surge protection  yet, you should unplug the ISDN cable from the codec when you’re not using it.

Let me know if you have questions or comments about surge protection. Thanks,