[TowerTalk] XHHW wire

[Grant Saviers]

Wikipedia explains in detail the issues with aluminum wire - old alloy 
creep, corrosion, dissimilar expansion, galvanic corrosion, etc.  Plenty 
of references.

https://en.wikipedia.org/wiki/Aluminum_building_wiring

Aluminum is the standard for mains wiring and commonly used for 
conductors to subpanels, hot tubs, stoves, dryers, etc 50a or larger. 
Modern Al alloy wire properly installed on correct connectors is 
reliable and safe.  Copper is rarely used for 15/20a branch circuits for 
all of the reasons enumerated in the wiki post.

I've checked main lugs (hot side of main breaker) to Al feeders on 
several 200a and one 350a panel and found them tight and all had the the 
corrosion inhibitor applied. Doing this is not advised with energized 
feeders, as a primary short is nothing less than catastrophic/fatal.

Grant KZ1W

On 2/24/2020 06:09, Patrick Greenlee wrote:
> I have 375 amp service (or was it 350?) anyway the wires from the pole 
> xformer to the house are buried and are aluminum. They feed side by side 
> 200 amp panels, each with a main breaker. I have never touched their 
> connection to the main breakers.  This setup has been in place for over 
> 15 years.  I can kill the main breakers one at a time and use an allen 
> wrench with a "cheater" for increased torque to make sure the clamping 
> force is good and plenty but I suspect I'll find the connection to be 
> tight.
> 
> Sub panels off these 2 each 200 amp panels feed healthy arc welders, 
> table saws, kilowatt linear, etc and other man toys with no problems. No 
> dimming or blinking lights.  I'll trport back if the 15 + year 
> connections have loosened any.
> 
> (Why 2 ea 200 amp panels instead of a single 400?   A good 400 cost then 
> $1200-$1500 so 2 ea good 200's was a comparative bargain, saving several 
> hundred dollars.)
> 
> Patrick        NJ5G
> 
> On 2/24/2020 7:46 AM, Rob Atkinson wrote:
>> I have a few problems with this wire.  My experience with aluminum is
>> that it is not worth the trouble integrating it into the rest of the
>> antenna system when it comes to bonding it to other metals.  I
>> appreciate the light weight and lower cost but aluminum has another
>> undesirable property:  It cold flows so clamps on it eventually come
>> loose and then you have resistance and heat.  This is why aluminum
>> house wire which was tried in the 1960s came to a quick end--too many
>> cold flows, heat and fires.   I hope it isn't coming back for that
>> purpose.
>>
>> I have my 200 amp service drop to my home using aluminum.  I don't
>> like it but I can't make the power company use copper.  Every few
>> years I check the lugs on the main breaker to make sure they are still
>> tight.   This is one area where an IR camera would come in handy.   It
>> WILL cold flow eventually and you'll know it when your lights flicker
>> or dim briefly when a big load like A/C comes on.
>>
>> I was dismayed to see that QST ran an article by some sort of RF
>> expert on how to construct open wire feedline using aluminum AWG 8 or
>> maybe it was 6, stranded wire.  Ridiculous overkill for ham power, and
>> he spliced line sections together using what appeared to be steel
>> clamps.  Those clamps will lose their grip in a few years and he'll
>> have problems, besides the use of steel for RF.   None of this came up
>> in the article.    Then there was the line Z due to the spacing and
>> diameter of AWG 8 cable but that's outside the focus here.
>>
>> 73
>> Rob
>> K5UJ
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