[meyer]

Here abouts the power company mounts similar at the service entrance weather head. While I think they could be useful, a powerful EMP or lightning strike would - it seems to me - overwhelm such a small device. I am skeptical.

There is actually a lightning arrester built into the electric meter/base, whereby the extreme voltage of a lightning strike will jump a small air gap between a metal piece tied to the hot wire and the grounded enclosure of the meter. Crude, but mostly effective.

Lightning arresters are also out on the lines, spaced occasionally, to perform the same function. And, near substation transformers, there is usually a set of lightning arresters that serve to protect the transformer from transient over-voltage. I don't know how effective they'd be against an EMP - I suppose, it depends on how powerful the EMP is.

[lgjhn23]

“....There is actually a lightning arrester built into the electric meter/base, whereby the extreme voltage of a lightning strike will jump a small air gap between a metal piece tied to the hot wire and the grounded enclosure of the meter. Crude, but mostly effective....”

Yep. The new code calls for the bare #8 meter pan ground wire to now include termination on two 8’ ground rods at a minimum of 8’ apart with no breaks in the ground wire allowed. It should quickly drain off any static build up that contributes to a strike. However, anything is possible these days, even in nature.

[Bob Ireland]

***I don't know how effective they'd be against an EMP - I suppose, it depends on how powerful the EMP is***

An EMP is, as it's name implies, a strong magnetic burst. We build faraday cages to build an anti-magnetic shield around vulnerable objects, like electronics. If a tiny box with a few small wires would do the same job we would all look rather foolish building large magnetic shields.

As for lightning, take it from me, someone who has been hit by lightning; these small gap conductors are helpful up to a point. Over a proper voltage at an adequate current, lightning will go wherever it wants looking for a strong ground in order to discharge itself. The power company attaches no guarantees as to the effectiveness of its devices. Some surge protection companies, like Tripp Lite, guarantee to pay for equipment being protected if damaged; they can handle a pretty fair load. The few strong hits they cannot block they will pay off; it is good advertising. My antenna tower and my solar tower are well grounded.