OP said:
A few years back I lived in Arlington, TX. We had a bad thunderstorm roll through one afternoon and lightning struck the transformer that fed our home and several others, and it blew the transformer off the pole into my backyard. I incurred ZERO damage, and my power feed was the closest to the transformer.
You were just lucky that day. The SPD (Surge Protection Device) did not save your home that day, jmho.
Just curious was the overhead power line from the transformer to the house broken, knocked to the ground, at the pole by the lightning strike physical damage to the pole and transformer? If yes that might explain why your house was spared.
Here is some SPD reading material.
https://www.nemasurge.org/faqs/ What are surges, transients, and temporary over-voltages, and what are their typical characteristics?Although often used as separate terms in the surge industry, Transients and Surges are the same phenomenon. Transients and Surges can be current, voltage, or both and can have peak values in excess of 10kA or 10kV. They are typically of very short duration (usually >10 µs & <1 ms), with a waveform that has a very rapid rise to the peak and then falls off at a much slower rate. Transients and Surges can be caused by external sources such as lightning or a short circuit, or from internal sources such as Contactor switching, Variable Speed Drives, Capacitor switching, etc.
Temporary over voltages (TOVs) are oscillatory
phase-to-ground or phase-to-phase overvoltages that can last as little as a few seconds or as long as several minutes. Sources of TOV’s include fault reclosing, load switching, ground impedance shifts, single-phase faults and ferroresonance effects to name a few. Due to their potentially high voltage and long duration, TOV’s can be very detrimental to MOV-based SPD’s. An extended TOV can cause permanent damage to an SPD and render the unit inoperable. Note that while ANSI/UL 1449 ensures that the SPD will not create a safety hazard under these conditions; SPDs are typically not designed to protect downstream equipment from a TOV event.
TOP
What are multi-mode SPDs – why do I need L-L (line-to-line) and N-G (neutral-to-ground) protection?Multi-mode surge protective devices (SPDs) are devices which comprise a number of SPD components within the one package. These “modes” of protection can be connected L-N, L-L, L-G and N-G across the three phases. Having protection in each mode provides the protection for the loads particularly against the internally generated transients where ground may not be the preferred return path. In some applications such as applying an SPD at a service entrance where both the neutral and ground points are bonded there is no benefit of seperarate L-N and L-G modes, however as you go further into the distribution and there is separation from that common N-G bond, the SPD N-G mode of protection will be beneficial.
Here is a video showing what happened when a power transformer failed.
https://www.wwltv.com/article/news/local/jefferson/transformer-blows-in-kenner-killing-power-for-mor...
An SPD would be worthless in this instance if the high voltage power came in on the electrical service wiring of a home.
