[RE-wrenches] Soldering electrical conductors

[Joel Davidson]

Good wire splices and connections require good mechanical connections first. Some people like to solder the wire after they make the mechanical connection, but solder can hide a bad mechanical connection and provide a place for corrosion to form.

Joel Davidson




________________________________
From: The Office of Tom Duffy <tom at thesolar.biz>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Wednesday, December 3, 2008 9:48:28 AM
Subject: Re: [RE-wrenches] Soldering electrical conductors


About 28 years ago I read a study, by either Niehoff or Prestolite, on the pros and cons of soldering or crimping, heavy duty starter cables, for over the road trucks. 
 
The finding was, that a properly crimped lug made a solid (molecular) connection while solder did not make as good a connection because solder was not as good a conductor as copper. They concluded that the crimped connection carried more amperage and did so over the long haul. 
 
We use an air over hydraulic crimper on all our cables with a hydraulic gauge reading of 10,000 lbs PSI. I have done a pull test with this connection by pulling a truck behind another with this connection
 
Tom Duffy
The Solar Biz
From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of North Texas Renewable Energy Inc
Sent: Wednesday, December 03, 2008 10:08 AM
To: RE Wrenches
Subject: [RE-wrenches] Soldering electrical conductors


Wrenches
Over the years I have heard almost nothing about soldering of electrical connections in PV circuits, AC or DC. The only reference I recall is from the recommendation that one should crimp AND solder larger compression fittings to assure a permanent connection. There were references to factory made battery cable crimps not holding after installation and during the final "pull-test". 
I can't find any reference to the practice in the NEC, either pro or con. It seems that any technique so susceptible to poor results would be at least addressed. 
The reason I want to definitively address this practice, by the Wrenches community, is this.
A group of PV industry specialists were invited to help develop a curriculum for a state funded technical college with 4 separate campuses. The Waco Campus, with the fuel cell and wind degree programs,  is now creating a solar installer technician degree program. 
A group of experts spent two days picking our brains to help create an overview plus detailed duties, tasks and the separate steps involved in the design/installation process.
So now that the initial draft is finished we are asked to critique it. One of the "General Knowledge" items is soldering techniques. 
I need to mention that the degree will cover both PV and thermal installs. Of course some soldering is necessary in the thermal installation process, less since the introduction of compression connections, but I'm interested in addressing the electrical side. 
If any negative long-term effects from solder joints have been discovered I would like to hear about them. If they seem serious enough, I would consider recommending that the staff include a clarification that electrical soldering should be avoided. If the long-term effect is negligible, it is still possible to do an electrically poor job even using top quality equipment. 
I'll defer to the collective knowledge of this organization.
Thanks as always
Jim Duncan
North Texas Renewable Energy Inc
817.917.0527
ntrei at earthlink.net
www.ntrei.com 
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