No technology located in a circuit breaker or fuse panel could detect a high-resistance wiring fault, as no measurable characteristic exists that differentiates a glow fault from normal branch circuit operation. Power Fault Circuit Interrupters (PFCI) located in receptacles are designed to prevent fires caused by glowing connections in premise wiring or panels. From the receptacle, a PFCI can detect the voltage drop when high current exists in a high resistance junction. In a properly designed circuit, substantial voltage drops should never occur. Proper wire terminations inside utilization equipment (e.g. appliances, lamps, heaters) and cords prevent high-resistance connections that can lead to fires.
Excess current can heat entire lengths of wire. Thermal circuit breakers are designed to protect against excess current through the permanent circuit wiring. However, excess current through the smaller wires in utilization equipment can exist, at levels below the trip thresholds of a circuit breaker. Overload fault circuit interrupters (OFCI) are designed to protect against excess current drawn by utilization equipment. OFCIs must be located within receptacles. Both thermal circuit breakers and OFCIs are required to prevent fire ignition from excess current.
One might recall the point of use debates that circulated when the afci debuted....
The interesting thing is, this product, apparently predicated itself via Joule's first law of thermodynamics>
Product DescriptionThis device consists of multiple sensors which detect abnormal heat at each outlet contact and binding head screw terminal. When such heat is detected, the sensors activate, the load fully disconnects, and an indicator pin protrudes from the face of the device. The user can easily see that abnormally high heat activated the device, which is no longer functional – a feature that prevents further damage to the existing wiring. We recommend that a licensed professional inspect the fault condition and replace the outlet.
So, instead of having Mr. Strauss spend his time answering to just one electrician, begging the induldgence of the moderators ,i've asked him here to explain it en masse' (and Mike, if you can sell this crew, your in like flint!)
Just a little thing about terminations at fittings themselves. Now I'm not trying (or willing) to put the boot into the way things are done in the US, but I've never really liked the idea of the "wire under the screw" method of connecting a wire to a device.
Having said that, I don't have a problem with it per se, where an electrician that does heaps of these connections every day of the week and can just about do it with their eyes closed and with the proper tools.
But, when you get someone doing their own electrical work at home, there is a chance the copper could be nicked or some of the copper wire stripped away, resulting in a lower integrity connection with the screw and a higher resistance connection. Or you have the person that winds the wire around the wrong way and it moves out from under the screw as it is tightened. For this reason alone, I prefer the tunnel type terminals we use over here, they are virtually fool-proof.
I do however, like the concept of the receptacle that Bill linked to, a LOT of energy is dissipated at bad connections.
Let's face it, these days if you're not young, you're old - Red Green
Trumpy: FWIW, we have 'tunnel' terminations on devices here, on 'specification grade' devices.....which are premium $$ priced. They always were my 'choice', and were great with stranded conductors. Keep in mind also on this corner of the world, the NMC is solid conductors.