ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Increasing demand factors in residential
by gfretwell - 03/28/24 12:43 AM
Portable generator question
by Steve Miller - 03/19/24 08:50 PM
Do we need grounding?
by NORCAL - 03/19/24 05:11 PM
240V only in a home and NEC?
by dsk - 03/19/24 06:33 AM
Cordless Tools: The Obvious Question
by renosteinke - 03/14/24 08:05 PM
New in the Gallery:
This is a new one
This is a new one
by timmp, September 24
Few pics I found
Few pics I found
by timmp, August 15
Who's Online Now
0 members (), 255 guests, and 16 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 3 of 4 1 2 3 4
Joined: Feb 2002
Posts: 2,233
H
Member
Reno brought up a point about UL listing. I have a question. Can you install AL wires on a CU busbar? or terminal?

Joined: Apr 2002
Posts: 7,381
Likes: 7
Member
Harold:
The answer to Al conductors on a Cu bus would be dependent on the lugs used to terminate the conductors being suitable for Al conductors, and Cu mounting. Most are dual listed.

As to the lugs being suitable to mount on Cu, the mfg data would answer that. The lugs that are factory attached to buss (a MLO panel) are usually dual rated. The question of suitability of field installed lugs on buss (industrial) is 'show me the mfg data'.




John
Joined: Feb 2002
Posts: 2,233
H
Member
John,
I am talking about landing a wire without connections directly to a copper ground bar. I was reminded by an AHJ that we should not allow AL wires to be landed on copper ground bars. For example Ilsko D-176 web site here:

http://ilsco.com//TechnicalDrawing//N0009.pdf

States that it is UL listed for CU wire only.

YET, when inspecting a Generac transfer switch the EC on the job I was going to red sticker the job. The EC on the job asked me to read a small label in the top left corner of the switch. He had to move the wires out of the way so that I could read it. It stated that all of the connections in this transfer switch was UL listed/labeled for CU or AL wires.

Now that seems to go against the manufacture of the ground bar listing. Should you pass it (and accept the UL listing of the switch) or fail the job (Because AL wires on copper ground bar is not allowed by UL listing)?

Joined: Apr 2002
Posts: 7,381
Likes: 7
Member
I'll have to look at a Generac in the field. On what you say, you are faced with contradictory data within the enclosure. My first opinion would be to check the mfg install books, or call Generac. I guess that EC was running SER cable?

Thinking harder the wording of the label "connections within" could be referencing the factory wiring within the switch, not the field connections.

Sparky may want to think about crimping a Cu tail on the Al & call it done. What do you think??



John
Joined: Jun 2004
Posts: 1,273
T
Member
This 'conflict' is resolved by remembering that the ampacity of aluminum vs copper is quite different.

When a copper grounding bar is listed, it is for a rating, a rating whose ampacity vs the wire portals (those side holes) would work as specified for copper – yet only at a de-rated level if aluminum replaced the copper conductors. Field installers/ electricians are not permitted to re-rate grounding buses downwards or upwards. We're not in the EE business.

When the exact same situation occurs in an engineered, manufactured, tested and listed assembly the entire configuration is synchronized so that -- for that assembly -- aluminum conductors inside the 'copper holes' fits the ampacity requirement.

They perform the tests that a practicing electrician is in no position to do.

Hence, both labels are correct.

All of the above is why you should go with the listing label and avoid field engineering/ second guessing the factory.

BTW, one last shot: even the aluminum alloy used to make conductors varies. Todays aluminum conductor is much, much more thermally stable than the old stuff. Once it was accepted that the original alloys were expanding and contracting too much for consistent safety, steps were taken.

When aluminum conductors are mated with mechanical lugs of modern design – they give trouble free service. So much so, that my Pocos won't install copper, as a matter of policy, unless they absolutely have to – and the customer pays up for the conductors. That payment must come in advance – weeks in advance – for the order will be custom – brutally expensive, in fact.

Last edited by Tesla; 01/18/13 01:38 AM.

Tesla
Joined: Feb 2002
Posts: 2,233
H
Member
John,

Sometimes it gets so confusing out there that I can see why AHJ's don't care anymore. I hear from many, many EC's that, "I don't get failed for that in other towns!" As an AHJ, I don't want to be a pain in the a**, but I also want everything to be safe out there too. I try to treat every job almost like my own. First thing I look for is safety.

Another place I get this confusion with listings is pool heaters. How many manufactures are getting listing on pool heaters with AL lugs for bonding. That drives me crazy. I think we already had this discussion before.

Joined: Apr 2002
Posts: 7,381
Likes: 7
Member
Harold:
I feel your pain. I hear 'xxx' in next town over is OK with this. 'xxx' said this is good.

When I take my cell phone & say 'let me call him', the story changes. Or on occasion 'xxx' says to me ' I did not say that'; or 'oh, I thought that was OK'.



John
Joined: Jun 2004
Posts: 1,273
T
Member
Harold...

There's quite a price spread between copper lugs and aluminum lugs.

Right off the top of my head, I wouldn't trust ANY aluminum alloy as a viable conductor whenever Chlorine is present.

Hydrochloric acid reall goes to town on aluminum...

But, at a slower pace, so does hypochloric acid... table salt, road salt, and ground salt...

(Bleach is the sodium salt of hypochloric acid: sodium hypochlorite.)

----------

And, I can't think of the last time I saw copper bussing or copper lugs with a listed hot tub assembly.

It can't represent even 0.01% of the cost of the unit to go with copper.

What gives?


Tesla
Joined: Feb 2002
Posts: 2,233
H
Member
John,

Sometimes when I hear that another town doesn't fail me for "whatever", I sometimes say , Well I know for a fact that towns 1,2,3,4,5,6,7,8,9,.. will fail you for this because I work in several of these towns, and the rest of them are my friends and I know for a fact that they will fail you for this. They told me so. That usually shuts them up real quick.

Joined: Feb 2002
Posts: 2,233
H
Member
Tesla,

I have been seeing AL lugs on pool heaters again and on hydro massage tubs. I don't recall seeing AL lugs on hot tubs, but I haven't seen a hot tub in a few months now. Next one I get I will have to check again.

Last edited by harold endean; 01/20/13 01:31 PM.
Page 3 of 4 1 2 3 4

Link Copied to Clipboard
Powered by UBB.threads™ PHP Forum Software 7.7.5