Finding a break in a circuit

[Anonymous]

I own a home built in the 60's that's wired with aluminum. Part of one of the circuits upstairs went out, and I am unable to find the source of the problem. I have tried replacing all the affected switches and outlets (this needed to be done anyway so I could pig-tail them) with no luck. I jumped power from the functioning part of the circuit to that part which doesn't work, and all the affected devices have power using this trick. The house is wired in a very confusing way so I can't say with any certainty what the path of the circuit is. Do you have any advice on how to isolate the problem, short of tearing out walls?

A friend of mine suggested running a line from the source line where it comes up from the breaker box, to the affected end, but I am concerned about the place where the circuit is broken being a fire hazard. What do you think?

[Wgoodrich]

You are right, what you most likely have is a loose connection. A loose connection with current flowing through that loose connection left unattended without repair is a fire waiting to happen. Aluminum wiring in smaller conductor sized such as 14, 12, 10 awg installed in the 60s and 70s are well known to have loose connections appear. You did a good thing replacing your old switches and receptacles with the newer style switches and receptacles as long as you used the type switches and receptacles approved for use with this older aluminum wiring. You receptacles or switches must say approved CU/ALR not CU/AL. The "R" tells you that your new switches and recpetacle devices are with the newer type alloys that are more compatible with the aluminum wiring that what the older style receptacles and switches were allowing for more reliable connections with aluminum wiring.

In your search for your loose connection you need to become an investigator. Turn everything off in the house circuit by circuit. Then turn on that branch circuit that you lost part of the circuit from power. Draw on a piece of paper the layout of your house then on that piece of paper mark in each room the switches, lights, receptacles that are still working with only your one damaged branch circuit turned on. Then go back to the panel and turn on all your breakers. Test everything in your house and mark on your piece of paper where the dead receptacles, switches, and lights.

This should provide a map how your entire damage branch circuit is layed out in your home. In your mind you should be able to now tell where power entered the circuit and where the circuit stopped working. Then using that map look for the point where the power stops on the circuit.[remember both sides of the wall can be wired back to back] I am guessing considering the time frame of your wiring that the branch circuit was wired from receptacle to receptacle with power entering either the switch or lights either being in the switch or lights. If a pro wired your home in that time frame it was common that double and triple and four gang light switch boxes were used to branch out power more than one direction on that branch circuit. Your loose connection will most likely be found in a double, triple or four gang light box if you have already replaced all receptacles in your branch circuit. If you have not replaced all receptacles on this branch circuit in question then you should be aware that receptacles installed during the time frame also backstabbed the receptacles. Back stabbing means they plugged the wires into the back of hte receptacles. This back stabbing of older receptacle devices is a common location for a loose connection also. You may find the loose connection in the attic in a junction box but chances are it will be a back stabbed older style receptacle or a multiganged switch box with a loose wire nut. Look at your map that you built and imagine how the wires were ran at the point where the power is lost. The loose connection will be either just before or right at the point where the power is lost. Ofen times it will be a wire nut in the close viciinity of where the power was lost in a switch box or a back stabbed receptacle.

Let us know what you find and good luck

Wg

[Anonymous]

I found it! I had done everything you said, except the mapping of the other circuits. Once I did that I realized my assumption of what circuit the outage was on was incorrect. Anyway, the problem was a backstabbed outlet, as you said. Thanks so much!
So, I have another question for you. Now that I have isolated the problem, and replaced it and several other outlets and switches. But I wonder whether this will happen again, and if next time it won't be worse than a loss of power. Knowing that replacing my aluminum wiring will require me tearing up my walls, should I do this to ensure safety? Or as long as I replace all my devices should I be ok?
Thanks again... I (and my wife!) really appreciate your help.

[Wgoodrich]

Most old time electricians would say remove that smaller aluminum wiring smaller than 8 awg aluminum as fast as you can and replace with copper. This would be said very excitedly by those electricians.

However while I am not a big fan of the smaller aluminum conductors 12 and 10 awg sized in a home to serve your home wiring, the NEC still considers this smaller not smaller than 12 awg aluminum wiring to be installed meeting minimum safety standards even today as new installations.

To give you some background where this doubt festerred concerning the smaller aluminum wiring you need some history.

Back in the late 60s and early 70s the smaller aluminum wiring was installed new to the industry in new homes built in that time frame. This smaller aluminum wiring 12 and 10 awg conductors in these new homes worked fine for a period of time. Then loose connections appeared causing power outages as you have experienced and some fires occurred due to those loose connections.

At that same time frame back stabbing of receptacles were introduced and used in those same homes. Again these back stabbed receptacles and switches worked fine for a period of time whether used with aluminum or copper conductors were used. Then both copper and aluminum back stabbed receptacles and switchs started showing loose connections again causing power outages and some fires occurred due to these overheated loose connections due to back stabbing regardless whether it was with a copper or aluminum wire.

The back stab devices and the smaller aluminum wiring both had no previous track record at the time as to how these two wiring methods would hold up. Over decades of study of occurrences of loose connections due to the smaller aluminum wiring whether connected by back stabbing or by screws on the devices or wire nuts we discovered the alloy we used and the lack of antioxidantion inhibitor grease being installed on the aluminum connections were the cause of failure creating these loose connections.

Today we have changed the alloy connections [wire nuts, screws of devices, even backstab connection material] creating a more compatible alloy to the aluminum connection under pressure. This new alloy is where the UL listing created the CU/ALR that used to be marked CU/AL. The R designates that the new alloy mix created to stop the loose connection problem that occurred in the past is being used in these newer devices. The addition of the antioxidant grease and the more compatible allow connections while using aluminum wiring has been accepted and approved for safe use by the NEC in all aluminum wiring larger than 12 awg in size.

Remember that 90% of all electricity being brough accross the country from our power generators of the power companies are carried by aluminum wires and have been for decades with little or no trouble and a good record of reliability.

The back stab receptacle and switches also took just as strong of hit concerning doubt of safety as the aluminum wiring. In the days these back stab wiring being introduced we allowed both 12 and 14 awg copper conductors and 12 awg aluminum conductors to be back stabbed in the back of receptacles and switches. The back stab connections in receptacles and switches were failing when heavier loads were plugged into the receptacles and switches such as portable heaters and vacuum cleaners, window a/c units, etc.

When we discovered the track record of these older back stabbing of receptacles and switches, then there was an effort through the listing labrotories and the NEC so that now the new back stab receptacles and switches are made with a more reliable spring metal to make contact with the conductor. The new back stab wiring reduced the hole so that 12 awg conductors can no longer be installed in these new back stab receptacles and switches. This elimintated aluminum wiring from using these back stab devices because 12 awg aluminum is the minimum wire size allowed to be installed. Then the 20 amp rated 12 awg copper that carried the heavier loads through the old back stab connections also have been made not to be able to use the back stab receptacles and switches. The new back stab receptacles and switches can only take 14 awg copper conductors limiting the load to 15 amp to avoid overloading these back stab connections as was done in the past causing these failures of the older back stab devices.

AS you should see that we have and are learning as we discover problems from our past and made efforts to correct those problems in our new wiring designs and methods.

Now what to do with your old aluminum wiring. If that aluminum wiring is 14 awg aluminum then it should be removed from your home's electrical system as soon as possible.

If your aluminum wiring is 12 awg conductors then you need to buy the CU/ALR rated devices and read the instructions of your new wire nuts, receptacles, switches etc. that you are using to correct the mistakes of hte past concerning your older aluminum wiring. Then you need to remove the old receptacles, switches, and wire nuts and cut off the aluminum wire that was exposed and used to connect to the older connections. Cut back to new wire freshly stripped from the insulation. This will give you a good clean conductor to make a new clean connection. Then read the installation instructions that came with your receptacles, switches and wire nuts and install as your are instructed using newly exposed conductor where you stripped back the insulation and have cut off the old exposed original connection point on that conductor. Then you should be trouble free is you have done this throughout your home concerning that aluminum wiring.

It would be better in my mind to totally rewire using copper yet as an inspector the NEC says you would be fine if the installation is brought to new products on the market as done today meeting minimum safety standards of the NEC in today's code rules. Most often it is prohibitive to totally rewire the house the above suggestions is your best knowledge on the subject that I have for you. Now the decision is yours as to what you need to do in your condition.

Good Luck

Wg

[Anonymous]

Thanks for your advice and info. Isn't the internet a wonderful thing? I think what I will do for now is replace my devices with the CU/ALR devices. I will keep my eyes open for any other problems, and if anything at all pops up, then I will consider the more intrusive approach of replacing the wiring. Thanks again!

[Wgoodrich]

Don't forget to check connections in junction and light boxes that may be working loose also.

Good Luck and hope we helped

Wg