How often should Aluminum terminations be retorqued?
I ran into some really nasty ones the other day.

good Q.
it seems on initial installation that i can reef on a termination, and then gain somemore after a few hours.
usually, on a service call, i will give terminations a 'tweek' in a panel, along with sweeping out the dust bunnies, and working the breakers.

Never.

If you have some reason to believe the connection is loose, remove the conductor, trim the end back to fresh material & re-install using a torque wrench set to the value listed on the device

Are we talking wiring devices, lugs or bussing ?

Does any of all use anti seize on your alum. connection? It seems to help get lug a little tighter in a panel box.

I was wondering only how often you might suggest to your customers that they be checked?
Yes, I NoAlox it all. In the thread of the lugs stops the sqweeeeek
Tom's right-never without reterminating the connection


[This message has been edited by electure (edited 08-07-2001).]

Stu;
i think we're talkin' bigger stuff here, yet the same principals could apply to smaller.

i read some instructions, can't recall which, that asked no-lox be used as part of the listing ( it was refered to as something compound..)

today i busted off a meter lug, so a torque wrench is looking like a good idea. i was waaaaay out in the pukerbrush too, had to go 20+ miles to find the part.

as to the retorqueing;
what do other trades do, say mechanics. are different situations viewed differently? gasket vs. non-gasket? etc....

Steel can mostly be retorqued as much as you wish provided that the parts are cool to the touch at the time.

When a gasket is involved, the procedure is usually to torque once and leave it. Torquing may actually be a long process requiring that the bolts be tightened incrementally in a certain sequence. Some engines may recommend retorquing after the first 20 hours of operation. There are engines with no head gasket too... I suppose they could be retorqued any time they were cool... but again this should not be necessary.

I see torquing a conductor more as a matter of how big a dimple does it need. Once it has that dimple, it has deformed and the pressure will be somewhat relieved over time as the conductor is squished out. Retorquing it will cause the dimple to enlarge. The difference here is that copper and aluminum are much softer than steel.

agreed.
I was just wondering if other trades share our concerns here

After all, there are aluminum heads for cars.
Myself, i spent a decade putting together 6061 AL parts to specs of 1/10,000. The variables included all enviromental, as well as those introduced . The engineering aspects did not include any one-liner fits all explanations.
One item i do use is scotchcoat, which seems to isolate a termination well.

[This message has been edited by sparky (edited 08-08-2001).]

Sparky,

In your thread awhile back you were searching for a word instead of Noalox .. It had probably said "anti-oxidant compound"

Bill

>there are aluminum heads for cars.
When I said copper and aluminum, I meant, of course, wiring. Engine heads are obviously cast, not extruded. I don't know whether they are really aluminum alloys. It would be bad news if an engine part squashed out or twisted as easily as an aluminum wire does!

The torque requirement in some cases is actually the force to stretch the bolt a certain amount. Some refer to this as pre-load. For the head bolts on nuclear reactor vessels they screw on the nut, then use a hydraulic powered nut on the end of the bolt that stretches the bolt so the permanent nut can be run down manually. Some of the other torquing is done without a torque wrench. Run the nut to hand tight(which is good contact and no bolt stretch) then, based on the bolt type and size, turn the nut a certain number of degrees or quarter turns. The thread angle and the number of turns will determine the amount the bolt will stretch. I do not know how to figure this with copper lugs which will have to compress to give the pre-load instead of the bolt stretching. Maybe there are tables or tables could be derived based on the malleability of copper. That may be how the manufacturers determine the torque requirements. It would be simpler for them to tell us how far to turn the bolt or nut after contact, but it is easier to prove an electrician did not torque properly than that he did not make the required turns. The lawyer just has to ask for a receipt for the purchse of the wrench. If he has one then ask for the calibration info. If he has that make him prove he or an employee never dropped it.