Electrical Panel mystery

[mattl]

Been puzzled about this for years, somehow the screws seem to loosen on connections. On Christmas Eve a lot of my lights were flickering, blamed the power company. The next day some rooms went dark. Checked the panel and all looked ok, but flipped the breaker that controlled the area in question. Got a big arc at the top of the panel.

Upon investigating I saw some discolored insulation on one of the feed lines. This is a sub panel, was the original panel from when the house was built, 100 amp, I upgraded to a 200 amp panel decades ago. Flipped the breaker for the panel and found I could tighten up the screw on the problematic feed about a quarter turn, the other feed was fine. Years ago I did the same with all the breakers and did find a few screws loose. These were all firmly tightened up on install.

I' installing a new circuit panel in a few weeks and this will resolve a few issues and condense down to one panel. Been on my to-do list for a while, just a few hours work. I'm popping in a whole home surge protector something I've been meanning to do for some time too. Yes I'm doing it myself, been wiring for decades so no issues.

 

[fisherpaykel]

Loose screws

I don't have an answer unless the wires in question are aluminum which can move away from the firmly, or overly firmly tightened screw. I don't know if copper can also do that. I have replaced for a friend an aluminum wired non-functioning wall plug outlet where the wire did that and arced breaking the connection. The retrofit here in Canada at least in BC is a copper pigtail to the outlet and joined to the aluminum with a special aluminum rated wire nut and some anti-corrosion paste on the aluminum. Another case where cheaper isn't better.

 

[sudsmaster]

What brand is the panel/breakers?

 

[mattl]

The panel is an ITE Pushmatic circa 1965 all breakers are NLA. Yes the wire from the newer panel to the ITE is aluminum. Only idea I have as to why the problem presented is that over the years under heavy loads the wire heated a bit and over decades slowly eroded or expanded and contracted creating the issue. It's a large drop in current draw going from incandescent to LED, plus replacing most of the appliances with more efficient models.

Got a new 200 A Homeline panel on order from Amazon, will eliminate most of the aluminum wire. Need to determine what the 40" Frigidaire CI Range in the basement needs breaker wise, I think it has a 50A now, might be a bit oversized, but it does have a fairly long run of aluminum wire.

nl

 

[sudsmaster]

OK, I asked about the breaker panel brand because there's a known problem with Federal Pacific breaker panels with the "Stab-Loc" technology. And I became familiar with that issue because this house I bought in 1997 has an FP main panel, as well as two subpanels in the workshop. I did a lot of research on it, and apparently the early FP panels were OK, but somehow along the way, perhaps due to manufacturing issues, they started to fail. This usually was evidenced by arcing of the breakers. I had mine inspected and there is no such arcing problem, never has been. If there was any sign of such a problem, I would have had them all replaced. And so it goes. Also, all the wiring here is copper; I don't think aluminum wiring was ever approved for this county; perhaps never for the state of California.

 

[Sudster]

The Federal Pacific stab-loc breakers with copper teeth were not so much dangerous in  conductive issues as they were in  your personal protection. Your standard breaker today labeled with 15 or 20 amps stamped on the front will trip slightly above their rating, The Federal Pacific's were much less likely to trip and will kill you with ease. I know this as I have & had them all of my life .I have also been terribly shocked years ago . I have a personal friend (master electrician) who rails  against these old FP panels & breakers. If you sub feed from these it gets more involved and risky. Aluminum wiring ?  Not for me !

 

[cfz2882]

"cold flow" phemomenon with clamp type connections

whenever I repair or build industrial electrical equipment,I always check tightness of connections and often find some loose enough to begin heating under heavy current load.When I build this equipment new,I'll go back and retighten before equipment goes out to end user.

 

[sfh074]

My square D ....

panel main lug torque specs says torque to 21 foot pounds. Also use antioxidant paste for aluminum cable at each lug point. Stranded aluminum main cable, I've found needs to be retorqued at some point. After servicing many panels over the years, I've found main lugs with stranded aluminum cable needing tightening more times than not.

 

[combo52]

Loose Connections In An Older Electrical Panel

Hi Matt, your old Push-Matic panel was not designed for aluminum wire.

 

I potentially could have had the same problem at my house. I still have the original 1956 100 Amp PM panel in my house. In 1987 we doubled the house and had a 200 Amp Square D panel installed in the garage, the PM panel became a Sub-Panel on its own 100 breaker.

 

The electrician that installed the 200 A SD panel ran aluminum wire to the the old PM panel and I caught him and made him replace it with copper, it is only about 20 feet away so it was not too hard for them to do.

 

I Love my old PM panel, it is very well made with copper bus bars where the breakers screw to the BBs, it is much safer and more reliable than newer clip in breakers [ it is really more commercial in design ] I needed a breaker for this panel about 5 years ago and they were still available and I boxes of good used spares.

 

For you basement range unless you are going to go to town using both ovens and 3 or more top elements at once I would fuse it to 30 amps, if you do want to use it more heavily go with a 40 amp breaker, the smaller breakers give much greater safety with an old range.

 

John L.

 

[kb0nes]

I've had some similar intermittants on some high current connections in our shop. It seems to be a run away situation where contact resistance in the connection is slightly high causing localized heating. Thermal expansion works the joint loose, and then resistance increases making the problem more severe.

This shows the drawbacks of a fixed mechanical joint (screw clamping), if it loosens at all it will never tighten again. Spring terminal connections allow the joint to move a bit while still maintaining good contact. It is somewhat akin to the superiority of spring (Corbin) hose clamps as compared to the inferior worm gear clamps. The spring ones stay tight with changes in temp or cold flow if the hose material.

I have taken to treating all high high current connections with a smear of Caig Labs LS260Cp grease before tightening the connection. This has seemed to eliminate any issues by reducing contact resistance and warding off any oxidation in the connection. This is the best battery terminal treatment I have ever found too.

 

[sudsmaster]

Well, I've yet to be shocked by the FP panels here, and that's over 23 years, with a fair amount of renovations. I can attest however that I have managed to trip several of the breakers by overloading the circuits (like with a floor sander plus lighting on a 15 amp circuit). I have looked at Square D panels at HD and thought, yeah, some day. But so far, so good. I did have pre-purchase inspection and it concluded that the FP main panel didn't seem to have any issues. There are some new in box spare breakers in the workshop. I wondered why. Perhaps some failed in the past.

 

[mattl]

John, thanks for the info, yes I do use both ovens now and then but rarely use the top elements so a 30A might be fine.  Pulled up the specs on my Electrolux wall oven it's minimum is only a 20 amp breaker.

 

If I recall when I did this was mid 70's and copper was $$ so I think I went with aluminum. Went from overhead to underground service.  Also talked the utility into putting in a separate transformer for me and a couple of neighbors to share, prior to that I think we had 8 homes on one and had brownouts.

 

[tolivac]

I have a FPE Stab Loc breakers-No problems at all.And they trip if the circuit is overloaded.I have had these panels in-one apartment,and of all things a transmitter site.No problems at all with any of them.I did tighten the connections in the one I now have-circa 1972.The GUC power company here repled my underground lines-ran them thru conduit underground to the junction box in my front yard-then again with conduit to the junction across the street.Tools they used-two directional drill and a backhoe.And the transformer was replaced-the old one corroded on the base and it had the improper base.Was slowly sinking in the ground.And when they opened the front all kinds of fire ants!The linemen had to hose the transformer down with bug killer!Now everything is fine.The power commpany will do the same to other houses as the 50yr old lines start to fail.All URD.Know where the pole drop is for the street I live on.

 

[circlew]

Many manufacturers make 35 and 45 amp breakers. Eaton and Square D both offer them. Haven't seen them in HD or Lowe's, but distributors of those brands usually stock them.

I prefer panels with copper busbars, so mine are Eaton CH. The Square D QO series also has this feature.

 

[sudsmaster]

Yeah, back in the late 90's I researched the whole FPE power panel/breaker story and recall at least one source said the problems were associated with some manufacturing runs. I got the impression that the early FPE breakers were OK, but later ones did have some problems. And at that time the problems were arcing at the Stab-Loc connecitons, and this could be observed by inspecting the panel. Somewhere I have an inspection report that mentions that this problem was not observed on my panel(s).

I don't know the exact details, but I have gathered the main problem has been the design of breakers/panel connections, what FPE calls "Stab-Loc", where a forked piece of metal on one engages with the other, and that this could deteriorate and cause the arcing.

In any case, have had no problems with the FPE panels here for the past 23 years.

 

[perc-o-prince]

Pushmatic circa 1965 all breakers are NLA

Matt,

 

Our main panels are Pushmatic as well. Originally I was only able to get them at a mom and pop operation, Webster Electric, about 45 minutes away, but have found them on eBay in the last few years. An electrician friend of mine has checked the used ones I've gotten to be sure they seem OK to use. Maybe you'll have some luck there!

 

He's actually quoted me a damn good price to change over that panel, so I really should have it done, but there's a lot of that old cloth-type wrapped wire from the '60's there so I don't think I want to mess with it!

 

Chuck