Used all the time by telephone equipment providers. My office PBX (Private Branch Exchange) has an optional card that can be piggy-backed on the exchange line interface card with eight such double-ended tubes (ends to A/B, centre to ground). The option is only fitted by a repair technician after a lightning attack ;-), so it's expensive!

In the industrial weighing field, we use them all the time in external load cell junction boxes - usually on weighbridges. Not to protect against direct hits - you can never do that - but to protect against the local ground suddenly becoming several hundred volts above regular ground, due to a nearby strike. THAT's what you're protecting against. In the UK, this is not a serious problem (not like the American mid-west), but it's significant at our Irish installations. (Anyone need any lightning damaged 20T load cells?)

For a similar reason, you should always stand with your feet together, if caught out in a thunderstorm...

Dave

PS: In my very early days at the GPO's Research Centre (at Dollis Hill in London - shows my age), I did some testing on gas discharge tubes, to see how fast they would react. These were used to protect the in-line repeaters on coaxial undersea telephone cables. There wasn't much lightning down there, but they were powered by a constant current, fed down the centre conductor, so on a long cable - say transatlantic - you fed in -5000v at one end, and +5000v at the other (like a giant set of fairy lights).

Unfortunately, if a fisherman trawled up the cable (obviously near one end), and he had a good catch, instead of putting his axe through the nets (he would be compensated for the nets alone), he'd put it through the cable. Certainly must have made his eyes sparkle ;-) You can imagine the spike that goes down the cable to the first amplifier (three germanium transistors at 600gbp each in 1968 - the Post Office made them itself...

Anyhows, we needed fast ionisation. So I tested experimental tubes with differing amounts of some radioactive agent added, to speed up the ionisation. The test kit was at groin level on the desk, so as my boss leaned over it to see what I was doing, I asked him if he already had children...