Using Extension Cord with Freezer

[ItsJoanNotJoann]

You think old Bob will show up to read your reply to his SEVEN YEAR OLD post????

[Ed Pawlowski]

The size of the wire is more important than the length. If you used a

3' cord with 18 gauge wire it would be more of a problem than 100 foot cord with #10 wire. Think of the wire as a pipe. You can only get so much juice through it so bigger is better.

[Tony Hwang]

Ohm's law is very simple to understand. If you used extension cord of proper size(capacity to carry the current without too much voltage drop) There shouldn't be a problem. a/c or freezer has motor which draws peak current when it starts due to it's characteristics of inductive load) Undersized cord is even fire hazard.

[Stormin Mormon]

Wonderful! I've got a compressor that dosn't run on the extension cord. I've been waiting for someone to use ohms law and help me understand.

You da man!

- . Christopher A. Young learn more about Jesus .

. .

[taxed and spent]

Why would you have to "introduce" resistance to Ohm's law to arrive at Ohm's law?

[Ed Pawlowski]

Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points. Introducing the constant of proportionality, the resistance, one arrives at the usual mathematical equation that describes this relationship

[Tony Hwang]

'Cos unit of resistance is Mr. Ohm?

[Tony Hwang]

Ohm's law with DC circuit is straight forward dealing with just resistance. With AC circuit it has to deal with resistance and reactance by inductor and/or capacitor. Unit of conductaance(vs. R) is Mho, Admittance is Y(vs. Z)

[tony944]

(

You've identified the problem, voltage drop. The conductors have to be sized for the load. An 11,000 BTU AC is a large load. It also has a large initial startup current. That current over a

100 ft 16 gauge extension has considerable voltage drop. If the extension cord was 10 or 12 gauge, it would work, but it's still not advisable. The issue should be much less with a modern fridge or freezer. They typically only pull ~90W or so. Bottom line you want to use a short extension cord that is heavy enough for the load. 90 watts where the heck did you get that info. Must efficient unit will draw about 10 Amps. that mean 1200 watts on 120 volts. for AC unit #14 wire with max length of 10 feet above that length you should and must go #12 wire. service for apx. 50 feet if you run any AC on cord and wire or receptacle is getting warm consider safety and install larger supply "IT is a must"

[taxed and spent]

You miss my point. Ohm's law relates voltage, current, and resistance. You don't need to "introduce" resistance to a law that already includes resistance.

[Ralph Mowery]

I think that 90 watts is for a modern refrigerator.

I think we all agree that extension cords are ok, but they should be made out of wire that is large enough so the voltage drop is very low. The longer the cord, the larger the wire. Wire less than about # 14 should not be used on high current loads at any length.

[trader_4]

It's widely available, just look. That's what refrigerators and freezers made in the last decade or so consume.

Are you thinking AC instead of fridge/freezer? I said fridge/freezer pulls 90W and that an 11,000 BTU AC is a "large load".

[Ed Pawlowski]

90W is for a very old fridge. I just looked at the specs of a 33 cu ft side by side and it is 8.5A an 18 cu ft top freezer was 6A

[trader_4]

No, you have it backwards. Fridges haven't gone up in power, they went way down. I replaced my 20 year old one that was using about

250W with a side by side that's bigger, think it's 31 cu ft, the new one uses 90W. The 8.5A that you're looking at may be the max, instantaneous startup current. I've looked at a new freezer too during Sandy with my KillaWatt meter. It pulled ~350 W for a few seconds, then quickly started declining. After a couple mins, it was down to ~100W.

[trader_4]

Thinking about it some more, that 8.5A is probably due to the defrost heater that only comes on once a day? That would give you a 1000W heater, which seems reasonable.

[hrhofmann]

H. R. (Bob) Hofmann at att.net is alive and thriving on this group. My advice in 2008 is still good, and it's great to read that someone read my post and it actually worked out well for them.

Now, my current project is planning on putting ceramic tile down on a small full bathroom floor, and convincing my wife that I can do it and not call in someone else.

[clare]

Except the water analogy for electricity doesn't hold water, when you stretch it far enough. A 1 foot chunk of #18 cord could actually provide LESS voltage drop than 100 feet of heavier cable.

The resistance of 1 foot of #18 is roughly the same as 2.5 feet of #14 or 6.4 feet of #10 - so 100 feet of #10 will definitely drop more voltage than 3 feet of #18 - as long as the current draw does not excede the current carrying capacity of the #18

With stranded cord, that is about2-3 amps for the #18 cabtire or zip cord - or 9-10 amps for solid wire, or about 5 amps for 7 strand

[clare]

I had a table saw that would blow the 15 amp fuse every time I started it plugged directly into the wall, but would start and run with no problem on a 25 foot #14 extension cord. It was an induction/repulsion motor. The cord resistance dropped the starting current just enough to save the fuse.

[taxed and spent]

Of course the analogy holds. A 1 foot chunk of 1 inch pipe could actually provide LESS pressure drop than 100 feet of larger pipe.

[Mark Lloyd]

[snip]

The 5000 BTU AC I was using on my generator after last month's tornado was drawing about 4A.