> On 8/7/15 11:25 AM, David Gilbert wrote:
>>
>> I
>>
>> For lightning protection (or any high current application), solder seems
>> to me to be a very poor choice. Solder, including silver solder, almost
>> invariably will be the highest resistance element (and the weakest
>> thermally) in the system and will act like an explosive fuse if it takes
>> a hit. As Jim says, clamps or welds are the way to go for this.
>>
>
> I've used silver brazing in high current pulsed power (well over 10kA,
> 10s of kJoule) applications which had significant mechanical loads (from
> the magnetic fields). I don't think lightning impulses would melt it.
> The "action" is too small. If a AWG10 wire doesn't melt from the
> lightning, a thin layer of silver/copper/tin alloy isn't going to melt
> either.
>
> Done right (or even half right) brazing is quite mechanically strong:
> it's not like welding steel, but it's used in all sorts of strength
> dependent applications (e.g. bicycle frames).
><snip>
I think people are confusing two types of solder here. There are "low
temperature" silver solders (Stay-brite is one) that are basically
replacements for lead solder. These are the types of solder that can be
melted with a soldering iron or a small butane torch
Then there are "Hard" silver solders, which should really be called
"silver brazing rod", running from "sil-phos" on the soft end, and running
on up - some of them are over 80% silver - most between 15 and 50% with
melting points over 1200 degrees. Silver brazing is NEC approved for
bonding (basically they treat it like a cadweld)
Silver brazing has better electrical conductivity than copper! It is
laying down silver that is nearly sterling depending on the alloy (say you
use Harris Safety-silv45 - your joint will be 45% Silver, 30% Copper, and
the rest zinc
It's a case where the same words "Silver solder" are used for two totally
differnt things. In the model enginering field, we tend to use two
differnt terms "Soft Soldering" (which includes soft silver, Lead, Zn/sn
etc) and "Hard Soldering" which is the stuff that requires a brazing
torch, goggles, and is used to braze up things like pressure boilers and
the like
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