Hi,

> I would never connect transient protectors in series.

    Me neither.. Both will work worse if connected in series..

> Why are you using both varistors and gas tubes?  Their characteristics
> are very different, but in use they do almost the same job.  I use gas
> tubes for very large and long overloads, often to blow a fuse.
> Varistors are cheaper but fail open on large overloads.

    If you can limit the current going into the varistor having the gas tube
first and the varistor after a current limiting resistor can make the
circuit much more resistant to high voltage spikes. Sometimes even a circuit
board trace between the gas tube and the varistor makes them work nicely
together. If you have no current limit and put them close together the
varistor will just blow before the gas tube acts.

Best regards,
Alexandre Guimaraes

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