many household extension cords (and lamp cords) are 16 gauge (13 amps)
whereas the breakers on the circuits where they're used are 15 amps.
How is it that it's safe to use a 16 gauge cord? Even if the
appliance plugged into it uses less than 13 amps, it's possible that
the appliance might malfunction and draw more current: maybe not
enough to trip the breaker but enough to exceed the cord's rating.
This can be a problem if the lamp or fixture is 'mis-used'.. The lamp and
small appliance cords will have a UL approval tag on them.. Really doesn't
mean very much but the MFG of the lamp, small appliance is only suppose to
use that cord on a piece of equipment that could not, under normal useage,
over load that cord.. Say 180 watt bulb in a three way lamp or a toaster
would burn out it's elements before it would overload it's cord. (if you
dropped a fork into a toaster, it would contact the elements which would
burn out first).
But again, UL is mostly concerned with 'Normal Use', not abuse.
If you unscrew the bulb from a lamp and screw in one of those old two prong
recepticals and try to run a hot plate off of it, then the cord would over
heat but that would be mis-use or abuse.
I don't mean to talk down since most of what I am arguing is generalization
and personal opinions. Just the only way I can answer this question in my
Here's another thought for you... what if you run several extension
cords? most the the "amp" ratings /safe for cord are assuming you
plug directly into a outlet....
email: dallyn_spam at yahoo dot com
please respond in this NG so others
can share your wisdom as well!
Geez, you can't worry about everything. The chance of a malfunction sending
14a through the cord for a lengthy period of time is pretty remote. Most
lamp cords are smaller than 14 gauge; are you going to rewire them all?
On the other hand, most of my extension cords are 12 gauge, except for my
wife's Christmas decorations, because I don't need the added voltage drop.
The breakers are sized to protect the BUILDING wiring. Not extension
cords or appliance cords.
Many appliance cords are only 16 gauge or perhaps even smaller, so an
appliance malfunction that resulted in it drawing excessive current
would not need an extension cord to be unsafe.
Isn't that why the Brits have a pair of appropriately sized fuses inside
the plug at the end of the appliance's cord? That always made pretty good
sense to me, it provides an extra measure of safety for very little cost,
but it does make the plugs bulkier.
I know they use (or used to at least) a "ring mains" system with large
sized building wiring which can supply a significant number of amps to any
of the receptacles, but not all at the same time of course. That makes
those fuses in the plugs even more necessary.
Jeff Wisnia (W1BSV + Brass Rat '57 EE)
"If you can keep smiling when things go wrong, you've thought of someone to
place the blame on."
The 15A rating of 14ga wiring is operating under the presumption
that the wire is buried within insulation, has no ventilation, ambient
temperature > 30C, yadda yadda yadda. Which is what you get inside walls.
In contrast, the melt-point for 18ga bare copper suspended free in air
is 100A. Under similar conditions, melt point for 14ga is several hundred
Appliance cords generally aren't buried in insulation without ventilation.
Current limits are calculated from the heat produced by the wire, and the
likely rate at which it can be dissipated based upon its use.
A 16ga appliance cord is perfectly capable of carrying 15A indefinately
under most circumstances you'd use one in (legally). So is an 18ga cord.
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
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