|
[email protected] wrote:
|
|> On Sat, 09 Sep 2006 10:48:45 -0500 Bud-- <
[email protected]>
wrote:
|>
|> | Tom Horne, Electrician wrote:
|> |
|> |> "110.14 (B)
|> |> Soldered splices shall first be spliced or
|> |> joined so as to be mechanically and electrically secure without
solder
|> |> and then be soldered.
|> |
|> | "Mechanically and electrically secure" is commonly done by twisting
the
|> | wires in a pigtail splice.
|>
|> Just how much electrical contact exists between two solid copper wires
|> twisted together? Depending on the compressibility of the copper, it
|> could be rather small. It certainly is small where one wire contacts
|> another at an angle. Twisting would have a linear, twisted, line of
|> content for the length of the twist. But how much length is needed to
|> provide sufficient contact to avoid hazardous temperature rise? And
|> how well would it stay this way under the effects of slight corrosion
|> in the long term?
|>
|
| But the twisted wire is then soldered. It was a common practice when
| splicing in a box before wirenuts. My understanding is the twisted wire
| sets were pointed down and then a solder pot was raised under them. I
| have seen one of this type of joint fail, and one knob and tube tap fail
| where the tap wire was twisted around the running wire. In both cases
| the original soldered joint was bad ("cold" solder connection).
That's one of the worst ways to solder it. OTOH, I have in fact tried
to solder large solid gauge copper wire, and it's a bitch. An electric
solder gun is nearly useless. And a torch is very messy.