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 own mind.
Steve
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.
Well, gee, you can't have everything perfect. sometime I plug a 18 gage lamp into a 20 amp circuit.
It's only considered safe for temporary use.
"Steve" wrote in news: snipped-for-privacy@corp.supernews.com:
Does the use of a GFI outlet help in these situations? That is, would it cut off the circuit if overloaded?
THX Wayne
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!
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
-- 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."
Wayne Boatwright posted for all of us....
No, read up on GFCI please
According to Randy :
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 amps.
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.
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