Transient current can destroy metal oxide varistors, gas discharge tubes, and transient voltage suppression diodes, or they deteriorate over time. They can fail-safe by shorting the connection and protecting the electronics. Include overcurrent protection in the series with the surge protection component.
| There are two philosophies in overcurrent protection in case of a shorted protective
The threshold voltage of gas discharge tubes (GDT) tends to creep lower after numerous trigger cycles. In certain applications, you need to test them periodically if the threshold voltage is critical for the system.
It is best to design overvoltage protecting devices that you can easily and safely replace several times during the technical lifetime of the system.