Residential Aluminum Wiring GFCI receptacle installation 1

[bdn2004]

Manufacturer's don't make a GFCI receptacle that have terminals rated for aluminum wire...so you are forced to pigtail a short piece of copper and use the special wire connectors to a GFCI receptacle.

My question is that about the ground terminal...Can you terminate the aluminum ground wire directly to the ground terminal on the receptacle? It might not seem like a big deal, but with all the pigtails, wire connectors and the extra length of the GFCI, space in the handybox is very limited.

 

[dpc]

I doubt it. It depends on the rating of the terminal and basically I don't think there are any remaining 120V devices with terminals rated for aluminum wire.

The aluminum wiring would be a nice thing to get rid of.....

 

[stevenal]

The problem with aluminum involved overheating a resistive connection by load current. Since the ground only carries current during fault conditions, I don't see a problem unless there is so much resistance that OC fails to operate. In the end, it is up to the inspector.

Which special connector are you using?

Adequate space in the box is a code issue as well as an installation problem.

DPC,

Looks like CO\ALR devices can still be found at

http://www.builderdepot.com/browse.ihtml?pid=125784&step=5&prodstoreid=1929

Never saw a dimmer or GFI, though.

 

[bdn2004]

Thanks..I think that is sound reasoning. Incidentally, you can buy new aluminum rated receptacles at Lowes....but not dimmers or GFCI's. That is ridiculous I think.

Here are the alumiminum/copper connectors that Lowes sells.....

http://www.alcopstore.com/

Home Depot sells the IDEAL 65 wire connectors...that seem to be pooh-pooh'ed on a number of home inspector websites. It would seem to me that if the use of these wire connectors is soooooo bad they would be recalled by the manufacturer and surely Home Depot would not sell them.

Both methods have been used in this house.

What I would like to see is the actual number of houses that have caught on fire due to the use of aluminum wiring. In my lifetime of reading local news I count a grand total of ZILCH.

 

[dpc]

Thanks for info on 120V device rated for Al - I thought that was history. The pigtail splices are a pretty well accepted solution.

I guess I'd think that the cold flow issues would apply even for ground terminals without much current - I thought it was more an effect of the pressure of the terminal itself.

But I'm getting well outside my knowledge base - not that this has ever stopped me before....

 

[stevenal]

dpc,

The 15 -20A Al rated devices are history, since they had the same problem with heating. They were replaced by the CO/ALR rated devices the NEC now refers to.

Cold flow will exist, but your breaker will operate before heating has a chance to occur in the event of a high current ground fault. Of course the GFCI will cover the low current ground fault on the load side, and works even in the absence of a ground wire.

I replaced a few devices on an aluminum wired place. Most of the replaced devices were fine. The charred ones were the receptacles used for portable heaters and vacuum cleaners. None had any charing on the ground connection.

By the way, another way to acheive ground fault protection is to use a GFI breaker. Most of these are rated for Al (Al is still okay for breakers).

 

[HCBFlash]

GFI breaker would be a good part of a solution, no doubt, but I suspect your branch circuit wiring and neutral sharing.

Ideal 65s are great. I wouldn't even consider those little plastic cased chunks of set-screw busbar,,, unless you've got LOTS of room and patience. Personally I'd trust a 3M, Buchanan B-cap, or Ideal -RESILIENT type "wirenut" used with "Penetrox", but the 65 has a little extra feature to keep the anti-oxidant in the nut and on the conductors. I don't know why on earth the "Term-a-nut" wasn't made CO/ALR, it'd be the nicest way to do these dirty little tasks.

No, I haven't ever done a post mortem on a substantial, structure damaging fire verifiably caused by AL wiring,,, but I've seen and gotten to repair and replace plenty of burnt wire, receptacles, a burnt wall-plate with charred gypsum board, a GE breaker box complete with smoke stains on the wall, a burnt up furnace contactor type control, a garage door opener that died of just enough voltage just often enough to keep trying - at the behest of an ignorant homeowner,,,,,

If the place was mine, I'd sell it or rewire it completely. And I've told a couple people that too in the past.

 

[waross]

The killer for aluminum wiring is heavy, intermittent loads.
Toasters, hot plates, motors, etc. The problem occurs when the load current heats the aluminum enough to initiate "cold flow".
The problem does not have to start with the aluminum connection. A poor quality receptacle may generate heat through a bad connection to the connection plug blades. The heat is conducted to the aluminum connection. The aluminum expands slightly from the heat. When it expands, it cold flows and when it cools it will be slightly loose. The next time a heavy load is applied, there will be additional heat generated in the now loosened aluminum connection. The deterioration and damage is progressive.
Pig tailing with copper wires and using anti-oxidant in resilient connectors is a dependable, accepted fix.
It is labour intensive. It may take a week or more for an electrician to repair an entire house.
A good compromise is to pigtail the receptacles in the bedroom, the kitchen, the laundry area and any other receptacles that are liable to undergo heavy cycling loads.
Lighting circuits occasionally experience problems but are not generally subject to problems. Lighting circuits do not have the complication of poor plug connections generating the higher temperatures that generally start the cold flow/heating/deterioration cycles.
respectfully

 

[bdn2004]

Theoretically I understand all the good answers here.

The thing that gets me though is that as I change out some of the receptacles I have yet to ever find a loose connection....and they have all been here for over 30 years. And there has been the typical things plugged into all the outlets...coffee pots, vacuum cleaners, fans, etc.

If I did find loose connections it would alarm me and I would surely pay to have the house re-wired copper only. It just makes me wonder about a case study of EXACTLY the conditions that must be present for this to become a REAL issue.

 

[HCBFlash]

Loose connections - at the screw terminals - isn't the only or even dominant problem with AL wiring. Heat and conductivity is. Pure AL is a good conductor, and aluminum oxides are good insulators - aka dielectrics. Oxidization, and other chemical changes, can occur especially where there is contact of dissimilar metals (or materials for that matter). Even where the contact is AL to AL, the contact is not very good, because of the presence of oxides and oxidizers. Where the contact is between 2 metals and moisture is present electrolysis occurs and the "less noble" metal oxidizes at a compounded rate. Mildly put "aluminum ain't very noble". Air has plenty of Oxygen and moisture in it to support this entire process very nicely.

Incidentally, I've never seen pure, unoxidized AL, and I doubt that very many people have. That's because AL is an active enough metal that it's surface oxidizes almost instantly in any environment where oxygen is present. The oxidized layer is very thin, so that a highly reflective silver color can still be seen, but that initial thin layer is there. Just because it looks clean and shiny and pure doesn't actually mean that it is.

So, anyhow, with the oxides present, contact resistance is high. We're talking contact resistance as opposed to conductor resistance. With this resistance comes heat as power is applied and conducted. This additional heat accelerates and exacerbates the additional oxidization by corrosion and electrolysis. If the point is reached where the aluminum looks more white than reflective there is so much AL Oxide present that NO appreciable current would be conducted. Yes, THAT is how good a dielectric Alum Oxides are. And of course when that point was reached heat would again not be an issue, because not enough current would be conducted to even produce any significant heating.

In that middle phase, between virgin, perfectly pure AL with no oxides present, and insulator grade AL oxide is where the trouble lies. I don't know the typical condition of your wiring throughout the premises, but I'd bet that you could take apart ANY termination, flex the wire, and the insulation would crack. Aside from the physical absence of conductor insulation at the crack, you'd be looking at the irrefutable proof of the significant lasting presence of heat. Thermoplastic insulation has temperature ratings indicative of it's tolerance of heat, so that will indicate how warm those parts of the wire have been staying.

You can go to the aluminum wire marketing websites and literature and read all the "yeah-but"s as well as the methods and products developed to deal with these factors. For many large conductor applications AL is a good option, but small branch circuit wiring is not such an application. The AL industry doesn't even fight that anymore. Wire manufacturers will make AL wire if people will buy it.

There are still cheap, sleazy, stupid, pennywise/pound foolish people out there, some of whom could even be called electricians, that will install AL wire if it won't get caught by an inspector, or if the inspector can't or won't stop it's use. I can think of no legitimate use of AL conductors inside any building, with only a few exceptions in industrial occupancies. The "National Exception Catalog" notwithstanding.

 

[HCBFlash]

correction on my previous;
"galvanic corrosion" is certainly better and more accurate than "electrolysis"