Elec: Do you need to re-tighten Al service entrance cable?

Last May, I replaced/upgraded our service panel, meter base, etc. from the 35 year old Federal Pacific 100A panel to a 200Amp SquareD Q0 series. The service entrance cable running down the house to the meter pan, then to the service panel in the basement was replaced with 4-0 Aluminum SE cable. I used NoAlOx, worked into the conductors with a stainless steel brush, and torqued the connections down to the value listed on the panel and meter box. The lugs are rated for Copper or Aluminum conductors.
I did get a permit, and the installation was inspected and approved before the electric company re-attached the overhead lines.
Assuming I did everything correctly, once an aluminum service entrance cable is installed, do the connections periodically need checked and tightened? If so, would the two months since the installation be enough for them to have worked loose? Everything else in the house is copper; this is the first time I've worked with AL wiring.
The reason I'm asking is that a few times a day our lights flicker. It's only a fraction of a second or so, the kind of effect you get when something high current powers up (hair drier, etc.) It's similar to, but much shorter than the effect when our A/C starts. It isn't a consistent time and it doesn't seem to coorespond with any item in our house starting up. I think it just started in the last couple of weeks, but it may be that I just noticed it. They get dimmer, not brighter, so I don't think it's a floating neutral. I've noticed it on two or three different circuits.
There are several houses off of the same pole mounted transformer and I'm going to check with the neighbors to see if they are experiencing similar things. We moved in last fall, so we weren't here last summer; it may be normal for our neighborhood when everybody's running the A/C and stuff.
I've tried various newsgroup and web searches and have found some info, but nothing that seems to fit my situation. Most of the comments point either to a loose connection (which prompted this message), the pole transformer, or the problems associated with aluminmum wiring inside the house.
Since I just did the work recently, I wanted to try to eliminate all that I could before I contact the power company.
Any suggestions would be appreciated.
Mike O.
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My compliments. It sounds as though you did a nice job on your service upgrade. I am happy to hear that you got a permit and had the job inspected. If you had not replaced the Federal Pacific (AKA Fire Trap Electric) panel I would have suggested that you start there.
A loose connection might be the problem. You could double check your work in the service panel, but more likely you may have a loose connection somewhere in your interior wiring. After 35 years don't expect everything to be tight. You only need to torque down your aluminum service conductors every few years.
Something else to consider at this time of year (Summer) are brownouts. Your power company may be cutting back the volts a little to save their equipment from overload.
I don't know what kind of appliances and equipment you have in your home, but I have seen the same effect from office copy machines and laser printers. I forget exactly what inside those machines causes that, but it is a fairly well know trait. While they are on they do some sort of internal cycling from time to time and it causes lights on the same circuit to blink for a moment.
I suppose that it is possible if your neighbors had some high current equipment going on and off that you would feel the effects. If that turns out to be the case, then the power company may need to upgrade their transformer feeding your house.
Also a loose connection at the transformer is possible and if your neighbors have the same problem as you call the power company.
Good luck.
John Grabowski http://www.mrelectrician.tv

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Thank you for your kind words. It was definately a learning time. I do computer network wiring and have done a bunch of basic electrical work (adding circuits, outlets, etc.), but this was the first time I tackled a full service upgrade. A comuple months of research, calls to the inspector, etc. before the actual work. The inspector seemed pretty impressed with the details, and I ended up saving $800.
The problem I'm seeing with the lights seems to be on multiple cirucits, at least three. Assuming it is a branch cirucit problem, why would it show up on three circuits? We have gas furnace and water heater; I don't have any copiers or laser printers (BTW, it's the high temp fuser that causes the load on those units. It rotates the rollers so they don't overheat one area on the roller).
I figure I'll call the power company eventually, but I just wanted to try to eliminate anything I can inside the house before I call them.
- Mike O.

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It is refreshing to hear that a "Do-It-Yourselfer" did the homework necessary to get the job done right. You should be an inspiration to those contemplating projects.
Since the problem seems to be on multiple circuits, perhaps you should seek a common denominator. Are those 3 circuits on the same phase from the circuit breaker panel? Do any of those circuits share a neutral? Are there several circuits in one junction box?
Something else I would check. Turn on as many lights and appliances as possible at the same time. Leave them on for 30 minutes or so. Before turning anything off, go to your electrical panel and listen carefully for several minutes. It is not necessary to remove the panel cover. Listen for any arcing from the main circuit breaker. Also feel the main circuit breaker for any excessive heat. There is a slim possibility that you have a defective main breaker.
If it turns out that the problem circuits are all on the same phase, I would guess that the problem is somewhere along the power company's line from their transformer down to the meter socket if it isn't the main breaker.
If you have the time and the inclination you should try keeping a log of the events. For example: Time, date, outside temperature, rooms and circuits affected, etc. This information could be checked with the power company's record of brownouts or other disturbances. You could also compare notes with your neighbors to see if there is a correlation.
Sometimes an electrician has to play detective to find the culprit.
I would be interested in hearing what the problem was after you get it resolved.
John G.

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I've checked around, it seems this is a common occurance, especially during summer. One neighbor who's lived here many years says that she was told that the city upgrades the tranformers as they fail and that every once in a while you hear one in the neighborhood blow and then they replace it with a newer, higher capacity model.
I'm still going to contact the city electric division; who knows, maybe my call will be the final one they need to do a replacement on our transformer?
- Mike O.

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I had already checked the breakers for noise and heat, but didn't find anything out of the ordinary. I hadn't tried with everything on, though. The circuits don't have any interior wiring in common (shared neutral or common box). I didn't think about checking if they're on the same 120V leg, I'll look into that.
The log is a good idea, too; every little bit helps.
I'm leaning/hoping it's on the power company side. The neighborhood is at least 35 years old, and the outside pole wires, transformers, etc. are obviously not new. I'm wondering if the drops we're seeing are when other high-current loads at other houses on the same transformer would power up. The weather has been in the upper 80's with rain, so there's a lot of A/C units running in the neighborhood. When our compressor starts, there's a noticable dimming for about a 1/2 second; it seems reasonable that other houses on the same transformer would also pull down the voltage when they come on.
Again, the main worry I have is on the parts I did, especially the service entrance connections since 1) I haven't worked with the alum wiring much (and have seen all the horror stories), and 2) it's basically uncheckable (for me) since I can't get into the meter pan. I'm reluctant to mess with the two leads in the service panel while they're hot. I did check the neutral in the panel, it seems tight and OK.
I'll let you know as the story unfolds...
Mike O.

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If aluminum wire is installed correctly it will provide you with trouble free service. I am assuming that your service is overhead and not underground. From the information that you provided it sounds as though your installation was done right.
The problems that arise from aluminum wire are a result of its characteristic to expand under load and contract with no load. Over a period of time the expansion and contraction will cause the termination point to loosen up. When the termination is loose it gets hot and can arc with a load on it. The heat and arcing can cause the wire to melt and damage the terminals. That is why it is a good idea to torque down your connections every few years.
Copper expands and contracts also, but not as much as aluminum. Copper also has a higher melting point than aluminum.
It could be time for the power company to upgrade their transformer. It may have been installed before everyone in the neighborhood had air conditioners.
You should compare notes with your neighbors. Also, if you make a serious complaint to the power company, they could set up some monitoring equipment on the line to see if the problem is a result of their equipment.

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