to prevent electric shock. in the old days, the plugs were polarized to make sure (yeah right) that the chasis side was connected to ground,. in the case of ac, there is no real polarization, the polarity changes 50 or 60 times a second,. ac does not work for plating or dielectric effects causing corrosion.

 

Perhaps because the 'line' prong, having, as it does, less contact area, requires lower interface resistance to achieve acceptably low (total) connection resistance?

Best regards
HP

That makes sense... and maybe they plate the larger prong for aesthetic reasons? Hubbell is a brand that comes to mind.

 

to prevent electric shock. in the old days, the plugs were polarized to make sure (yeah right) that the chasis side was connected to ground,. in the case of ac, there is no real polarization, the polarity changes 50 or 60 times a second,.

The safety aspect is vested in the dubious assumption that neutral is connected to 'environmental' ground Thus we understand many 'things' can occur at or between load-center and receptacle!...

ac does not work for plating or dielectric effects causing corrosion.

As a point of interest, ELF currents are productive of certain electrochemical 'reactions' --- A demonstration of this may be had via passage of 60Hz through brine (i.e. NaCl+H2O solution) -- While observing the formation of an [electrode material] chloride + sodium hydroxide 'Sundae'

Best regards
HP

 

maybe they plate the larger prong for aesthetic reasons?

Though I don't know how it could be, even so, I assert it's more likely "bottom line" reasons...

Best regards
HP

 

You are right though that the round cable has more insulation than the standard cheap extension cords with just two zip wires. This cable has three wires inside and a round coating, so it has more insulation to deal with. But then why only the one end gets too warm.

I agree, there are generally two heating modes you are seeing.
1: General heating from cord wire resistance that can be trapped by good insulation and instead of being dissipated over the length of the wire is transfered to the end(s) as heat depending on each ends thermal conduction properties to the next set of conductors.
2: Connection resistance heating that is localized to ends of the cord.

The varying combination of the two might cause a zip cord with low connection resistance to feel cooler at the ends when most of the wire heat is dissipated into the air from the thin insulation over the length of the wire.

 

Get two more extension cords. When attaching these two to the test cord, leave a crack to insert a meter probe.

With the test cord ends in close proximity and under load, compare the hot lead voltage drop to the neutral lead voltage drop.

This should tell you if and where the problem is.

 

Thanks for the reply

Note, however, that the linked page states that functionality is extended only to near infrared --- Hence response to far infrared radiation (e.g. 'radiant heat', etc...) seems dubious --- All the same, you've got me interested in the 'response curve' for 'standard' consumer grade CCD imaging devices...

Best regards
HP

This assumes that the imager is a CCD. I believe that most low cost imagers nowadays are CMOS, not CCD. My understanding is that the spectral response of CMOS is a lot different than a CCD. Maybe WBahn can help us here since he has _much_ more knowledge than I have.