Arc Fault Breakers and Aluminum wire
Quickstep
| Posted in Energy, Heating & Insulation on
I just read the article in the January issue of FHB about Arc-fault Circuit Interrupters with a great deal of interest. I’m wondering if AFCI breakers would help make aluminum branch wiring safer. It is my understanding that the chief problem with aluminum wiring is that the connections can come loose and arc. Seems like AFCI would provide an added element of safety. As you might guess, I have an aluminum wired house. All of the outlets and switches have been replaced with new CU/AL devices and connections have been re-done with proper wirenuts. Even with al this, I still want to rip it all out and replace it, but I might feel better if AFCIs would further mitigate the problem. Can anyone offer a professional opinion on this?
Replies
They could.
Another problem with alum wire is that early versions/alloys were not vey ductile, so if they got bent a few times, they'd break. I barely pushed on one the other day in a main panel (a couple of inches away from the breaker with just enough force to bend #14 copper) and the sucker broke off at the breaker screw!)
AFCI's are a new technology and still somewhat expensive and, to some, unproven.
I'd make changing over to copper a priority, myself.
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"I may have said the same thing before... But my explanation, I am sure, will always be different." Oscar Wilde
I just sat in on our code seminar for the latest revision (Canadian Electrical Code 2002) and we now have to use them in bedrooms on new installations.
My impression is the come in 2 flavors, one is a breaker just like a gfci breaker and the other is a remote device capable of protecting downstream. I think it would be good insurance on you aluminum wire at the breaker panel. Prices are high now but expected to go down as they become more common.
Thanks for the info. For what my opinion's worth, requireing them only in bedrooms seems short sited. I know I'm being free with everyone's money, but a fire downstairs seems to have equal or greater potential for disaster as one that starts in a bedroom.
We were told the reasoning was, behind the bed is where most cords get squished and cause a arc. These claims come from fire departments in post fire reports.
This may just be the start.
"I know I'm being free with everyone's money, but a fire downstairs seems to have equal or greater potential for disaster as one that starts in a bedroom."
But how often is that fire "downstairs" caused by an electrical problem and not smoking, cooking, fireplaces, kerson space heaters, etc. Also in those locations if someone is there they would be awake to respond to the fire.
On the other hand bedrooms is where a lot of heating equipment is used (space heaters, electric blankets, water bed heaters, etc) and often with extension cords. And the people are asleep and if the fire is right on or very near the bed they might be on fire before the smokes can go off.
But the interesting thing about this is that older homes are the ones most likely to have these problems and they won't get the "protect" of the AFCI.
Also as I read the article the NEC requires ALL circuits that go into the bedroom to be AFCI protected. That includes the smokes. So if a fire starts in another part of the house where the smoke wiring goes through it can get hot and the insulation start to melting and the wires arc and the AFCI shuts off the circuit before there is enough smoke in the bedroom to sound the alarm.
Also they only detect a certain range of arcing. In the article Cauldew gives an example of a light socket that failed and it would not have detected that as the current was too small.
Also there is the question of false trips.
I have heard lots of questioning, but nothing specfic about if they are a) effective (that is will actually shut off circuits with arc faults before a fire starts and b) not have "too large" a number of false trips.
Maybe sometime in the future they will be required in other areas. But for now I don't see it.
I think that a number of areas are going so on requiring these to see if they do "work".
Here is an application you didn't cite.
In industrial panel shops (some contractor shops as well) the people doing the wiring, ring out the panel first (with a VOM) then do the power on test by firing it up with 120 or 480 as is necessary. I wonder if they make the arc Fault breakers for 240 and 480 yet? Seems like a great application. Ever see a piece of wire with an incomplete crimp on the lug light up? Wow! Lots of blue light and smoke before the circuit opens. Lots of damaged componentry as well.
The big joke is when a new guy powers it up for the first time one of the old timers slaps 2 2x4's together out of his visual area.
I have two of them at the moment to protect the knob and tube that is otherwise inaccesible. One thing to keep in mind is that they require a dedicated neutral for each hot which might be a problem in places wired with 14/3 and 12/3. In the brochure, it states that they recognize an arcing pattern, so just setting off a 60W bulb once might not be enough. As with all devices, you want a window that provides safety but doesn't also trip with the slightest pulse (like my neighbors car alarm). And i agree that the older hgouses which most likely need them for in-wall wiring problems will never likely see them. I had the service panel rewired in October of 2001, and they weren't required by code until Jan 2002 so I'm not sure what they require for service upgrades in older houses, and even then they delayed enforcing it as the manufacturers couldn't supply them fast enough.
Using AFCI's to protect the aluminum wiring sounds like a great idea to me, since the failures usually include arcing.
The 2002 requirement for older houses, at least here in Massachusetts, is that when a panel is upgraded that AFCI's be installed (on the bedroom circuits). Except when the wiring is knob and tube.
The newest fire codes require all hard-wired smoke detectors installed in residences to have battery back-up, so if an AFCI trips the smoke detector circuit , they will still function. So including them in the AFCI requirement when they are installed in bedrooms (and since they also must be interconnected throughout the house it means that the entire smoke-detector system if it's 120V is on an AFCI breaker) isn't quite as stupid as it appears.........
LEE
Using AFCIs may reduce the risk of fire in aluminum branch circuits. I'm looking into AFCIs to get more information. I would avoid using AFCIs, or GFCIs for that matter, as a substitute or excuse not to eliminate the aluminum wiring if at all possible. AFCIs may be a good idea in their own right but aluminum wiring, outside of properly landed and maintained feeders, is enough of a proven hazard to justify what ever measures it takes to replace the stuff.
I hear that as its worse, when every few days mobile homes with aluminum wiring were burning down faster than the firemen could get to them, some fire departments started buying them outright and wrecking them. The idea being that a few thousand spent getting it off the market was cheaper than pulling bodies out after the fact.
Regular homes don't burn as fast as mobile homes, especially the old ones, but the hazard is real. Replacing aluminum wiring should be the first choice. Everything after that is gravy.
4LORN1,
since you are researching AFCIs, maybe you can figure this one out for me. My brother in law has a 20 amp AFCI on a an appliance circuite in his kitchen (new house, closed last week). When the ice maker swithes on the breaker trips. My sugestion is to replace the AFCI with a GFCI and see if that solves the problem. I suspect there is a switch in the ice maker that is arcing when it starts up, and the AFCI is sensing at and triping. I shut the water of to the ice maker, and the circuite remained on with no problem. Since NEC does not require AFCIs on kitchen appliance circuite, there should be no problem with changing it.
Your thoughts?
Dave
Don't replace it with a GFCI.
There is no code requirement or logical reason for any fixed appliance like an icemaker, refigerator, or freezer to be on a GFCI.
Also the motors in those will often cause false trips and allow the contents to spoil.
For places like basements or garages that otherwise require all outlets to be GFCI protected there is an exemption just for fixed appliances (and that includes sump pumps).
"My brother in law has a 20 amp AFCI on a an appliance circuite in his kitchen"
If this is part of the small appliance counter top outlets then this is a miss application of the AFCI in the first place. Those outlets must be GFCI protected, by code. But more important that is where you have the danager and the need for GFCI. AFCI will not protect if you drop the electric knife in the sink and then go to pull it out.
If that is the cae replace the AFCI breaker with a standard one. Then install GFCI recptacles on the counter tops.
Exactly my thoughts Bill. However, the electrician that wired the house chose to use AFCI on the appliance circuit, and no GFCI receptical in the circuit. The inspector missed the improper use of the AFCI. I also think that there is only one appliance circuit, where code requires two, but I haven't been able to verify it. SIL does not care much for me, so BIL has to be carefull when he ask for my help.
Now does anyone have any idea what kind of arc fault I should look for and where to look on the ice maker? I would think that the ice maker has a micro swithch to bring it on, not a proximty switch, so there should be no arcing at the switch, but I am not an appliance repair person, so...?
Dave
I really don't know anything about an ice maker, but the problem might be inherent in it's design. It might be the thermostat in a defrost heater. It might also be centrifical start switch, both working as desgined.
But it might also be a loose connection.
Good suggestion Bill. I'll check them out.
Dave