Lightning protection GDT?

[Corbert-Beacon]

Beneteau 381 1996/7. I have a gas discharge tube (GDT) “CITEL 96 230v” in what I presume is a lightening protection circuit from the starboard chain plate to the forward keel bolt in approx 20mm sq cable. Is this standard? There are some old disconnected copper ribbons in the same place. I presume this might be protection from a high voltage cable strike, but won’t do much to protect from lighting. Any ideas?

 

[jwilson]

A hefty copper wire/rod/cable bond between rigging and keel is fairly common, particularly in boats sold and used in places like SE/Central USA where lightning storms are much more common than in UK/France. A gas discharge tube just about makes sense to me, in that it might possibly allow a pre-lightning static charge to dissipate to ground and avoid a full lightning strike.

It might on another circuit and be intended to protect electronics/electrics, but as you say will do nothing useful in a ful strike if the main "lighting rod" circuit has been removed. Did your boat come from the USA?

Opinions vary in the UK about the value of connecting copper wire/cable/rod to S/S rigging and hence to alloy spars - re galvanic corrosion. Hence may UK boats don't have lighting-grounded mast/rig to keels.

 

[pvb]

Opinions vary in the UK about the value of connecting copper wire/cable/rod to S/S rigging and hence to alloy spars - re galvanic corrosion. Hence may UK boats don't have lighting-grounded mast/rig to keels.

My boat has a copper cable from mast support to keel. I assumed it was an RCD requirement.

 

[ithet]

I have a Beneteau 331. There is a connection from starboard chain plate to keel which I think was original. I cannot remember offhand white type of cable it is.

Edit- French built model.

 

[William_H]

I would advocate a cable (heavy) mast base to keel. Any connection to rigging risks high current through stay wires which have significant resistance and so will heat and melt or loose strength. Ali mast no resistance so no problem in a strike. (comparatively).
GDT or more often just a close spark gap were once standard on telephone lines especially in country. 2 GDT one from each line to ground. They are not meant to carry high strike current but are there to bypass any high voltage that might be induced in the lines from a strike near the aerial lines.
I can't see any reason to fit GDT when a solid connection would do unless to avert galvanic corrosion. ol'will