Has your house burned down yet?
These guys will probably suggest you sleep in a motel tonight, just to be safe.
Not just any motel, but a Holiday Inn.
I’m a lowly mechanical engineer, but I do have an extensive background in failure analysis too.
Like I said, it isn’t pretty, and i’m not in any way defending the forming cracks, but I also know, from experience, that a lot of stuff that looks bad is actually superficial, given the loading and environment.
Let’s see some data. What is the temperature with 100 amps going through the lugs? What’s the load applied when installing or removing the breakers?
What is the actual material? Let’s see an sn diagram.
The other issue I see is that some junior engineer is sending non consumer replacement parts to a homeowner, whose skill level is completely unknown to the manufacturer.
What could possibly go wrong there?
The 3rd party confirmation that it is ok is what is being requested.
Easy fix, EATON sends a certified tech to change it out.
This site does have it's share of worry warts. Sick the government on them what a great idea. Geez. I have been installing CH panels since 1978. They are hands down the best residential panel on the market. Maybe an inspector asleep at the wheel I'm sure they will get to the bottom of it.
Obviously, those panels of yesteryear don’t look like these recent POS. Certainly a noted step down in quality to a product with a long history of reliability. They quickly changed from that questionable rev to something better since. That’s the problem. A change was made, looks very cheezy in some cases as pictured here. Not necessarily doomsday, but definitely not in the direction of betterness. Is there worse out there? Will these fractures get worse over time?
Accelerated testing could easily answer those q’s. The changes made should be supported by testing of the revised UL product. They should have documentation already on-hand at UL (other ETL). Should be just a formality to check it. If no one raises a red flag now to check them out, what must happen until it does get checked? If the CPSC were to get involved, they would probably contact the ETL first and could be quickly dropped.
With those checks done it is easy to determine if those product lots did in fact meet product release requirements. Better to ask the sheriff watching the hen house than the wolf.
I'm not a metallurgical engineer, but I am an electrical engineer with experience with connectors, connections, terminals, etc. Let me shed some light or those who are not in these technical fields.
It is entirely possible that these cracks are NOT showing up in the factory. The buss bars could look fine it the factory, however somewhere in the time frame during when it was shipped to the home improvement store, purchased by the owner, installed, or 2 years later. These are stress cracks and can show up and get worse with little more than the passage of time, and being made worse by thermal or mechanical stress. These stress cracks are the result of either poor design, manufacturing, or metallurgy, or a combination of those. If I had to guess I'd guess that the copper procurement guy decided to go with a cheaper copper alloy or supplier and the results of that change, we're now seeing.
There are perpendicular cracks across the bussbar, and there are cracks parallel to it where the buss bar is completely folded over. This parallel crack has me the most concerned. This type of connection relies on the copper to supply the spring force to make the connection to the breaker terminal. The parallel crack is right where that spring force would be generated. Thus, after the crack starts, there will NOT be the same amount of force applied to the breaker that it was engineered (and UL listed) to have to prevent loose breaker terminals and potential overheating.
The manufacturer "changed the process" to resolve the issue. Only time will tell if what they changed addressed the problem.
Brian
That’s my concern, do they get worse over time? I don’t know, and I don’t want to find out the answer is yes with my name all over that equipment.
Wouldn’t be the first time a procurement guy saved big in one aspect and blew up the mfg process elsewhere. It’s like a balloon, press in on one side and it gets bigger elsewhere.
The clamp load is in the breaker design, not the buss.
Max current any one buss will see is 50 amps.
50 amps requires between a 4 and five gage wire, about .2” in diameter, or .03 square inches.
Don’t know what the temp rise is on a 4 or 5 gage wire is at 50 amps, but in open air, I would doubt if it is 50 degrees, more probably 30 degrees or less. A 30 degrees temperature swing is not going to induce much thermal stress to the buss.
The suspect buss bar probably has five times the cross section of a 4 or 5 gage wire, at its worse point.
Again, I don’t like the looks of the buss, but nobody has numbers to say it’s a problem, and opinions are like.... you know the saying.
Max current under normal operating conditions could approach 200A. How did you arrive at 50A? Two 100A cb’s could be across from each other on the same stab.
There is also start-up inrush for motor loads.
There are also short ckt fault conditions to consider on the order of 10 – 22KAIC. Such as degraded bracing of the buss/stab assembly and further fracturing from the high thermal stress and movement.
A panel loaded with breakers is definitely not considered free air as the breakers will insulate any high heat generating areas. Continuous loads or repetitive starts will continue to produce heat.
The fractured horizontal buss stab (not the vertical buss bar) has much less cross-sectional area than 5x of a #4,#5 conductor.
CB overall width = 3/4”
CB width between stab supports = 9/16”
Stab width (w/o fracture) = 9/16” - 2*(1/16”) = 7/16”
@ 0.1” thickness, cross-sectional area = 0.044 sqin >>> #4 awg cu.
Stab width (w/fracture) = 7/16” – 3/16” = 4/16”
@ 0.1” thickness, cross-sectional area = 0.025 sqin >>> #6 awg cu.
(0.025) <> (5)(0.042)
The margin of safety you claim is not so big after all.
Of course, no one here has any data to support analytical methods (which require some assumptions) or empirical data acquired through accelerated testing. That is why the ETL and watchdog groups were suggested. Who wants to later be associated with bad news that may be associated with this product change?
It may not be dangerous, but the cracking was probably not designed into the product. If so, then it is either not working as designed or it is operating outside the design parameters. If nothing else many folks would be uncomfortable leaving that panel in service. In situations like this I have an adage that has served well - If something seems like it's not right then it probably isn't. Go with your gut.
I agree, it seems like a process out of control, especially when they quickly change it again.
I would not install these particular panels in any house. It’s not worth all the issues or second guessing. Just move on to another product or maybe just another product lot and get the job done.
