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Re: Solder on 120VAC?????

>Date: Tue, 29 Jun 1999 14:08:28 -0700
>From: Dave Gomberg <gomberg at wcf_com>

>At 03:48 PM 6/29/99 -0400, Wright wrote:
>>fittings should not be recommended, just like using solder on 120Vac
>>electrical fittings.

>Ooops, that's a new one on me.  What are the dangers/problems in using
>solder on 120VAC?   I know it is widely used and UL approved on all DC
>voltages.   What's the problem????

Solder is only about 10% (according to my failing memory) as conductive as
copper so a length X of solder of cross-section Y will get much hotter than
a similar length X of copper of cross-section Y at voltage E and current I.
It can easily get hot enough to start a fire if near plastic or wood. In
fact I have seen such connections that 'got lucky' and the solder acted as
its own fuse; melting and thereby breaking the circuit.

Note that a connection that has two pieces of wire joined by a bridge of
solder is not good on any circuit (well there may be specialized
applications like fuses) whether it's 120V or 6V. The problem is that the
120V circuit is much more likely to get hot and cause a fire. A typical 6V
consumer application will not have enough power to heat the connection that
much (you don't need to point out the current rating of your motorcycle
battery). To make a good connection the two copper surfaces should be in
direct contact (like wires twisted around each other) and the solder flows
in to fill all the nooks and crannies. I believe as long as it's done
properly UL approval is possible as well - just break open the transformer
that your portable radio uses to plug into the 120line; you'll likely find
that the transformer leads are soldered onto the 120V connection.

sorry for the off-topic folks (but we have to know enough about electricity
to be safe in our hobby)