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Could someone shed some light on the "do not use extension cord" and "provide a separate circuit" instructions that come with every single refrigerator and freezer?

Context:

I own this mini freezer and this refrigerator.

I'd like to plug them both into the same outlet, by first having an outlet splitter and for the mini freezer, an extension cord.

All the numbers seem to work out:

The mini freezer amperage is 1.1 amps; the Samsung refrigerator max draw is 3.5 amps; that's about 5 amps when they are both going hard.

I have an amp-meter, I monitored both of the appliances. I saw the mini freezer draw 3.5 amps for less than a minute when I power-cycled, so I am going to assume that's the compressor startup high current.

I hadn't yet been able to track the Samsung fridge compressor startup current draw, but let's say it's 3.5A * 3 = 10.5A.

So, only if both compressors were to startup at the same time (10.5A + 3.5A = ~14A) do I get anywhere close to the limit of the splitter and the extension cord? The outlet is 20A.

However - I am just a home-owner who knows just enough to be dangerous, so I should clearly understand the reasons why the warnings are there. I can't tell if they are there for the folks who, without these warnings, would plug in an oven and a microwave and a few other appliances into a 15A socket, or if these warnings apply to me as well, even after I did some sanity checks.

1
  • Location? My last fridge/freezer (and every previous one) is/was plugged in via a standard plug/socket.
    – MikeB
    Oct 30, 2023 at 10:18

6 Answers 6

24

They are related, but separate, issues:

Do not use extension cord

This is in general good advice for almost any appliance that is "permanently" installed. By "permanently", I mean "it is going to stay in one place and run for weeks, months, probably years without being moved or disconnected. There are several reasons to not use an extension cord in these cases:

  • Tripping hazard

This applies to using an extension cord with anything.

  • Accidental disconnect

This is specific to refrigerators and freezers. If you plug a light or a TV or a computer into an extension cord and somebody accidentally disconnects the device from the extension cord, there is no harm done. You find out it isn't working the next time you use it and you plug it back in. But with a refrigerator or freezer you have two big problems: spoiled food that you know about (which is bad enough) and spoiled food you don't know about (which is far, far worse).

The spoiled food you don't know about is because your refrigerator was unplugged for 6 hours. It got to 50 degrees for a couple of hours. Most people are notoriously bad at judging temperatures, so they stick their hand in, decide "it still feels cold" and figure everything is OK. Or even worse: Someone unplugs it, someone notices the problem several hours later and plugs it back in but doesn't check anything, a few hours later the temperature reads 38 F and nobody knows there is even a possibility of a problem.

Most beverages (except milk), fruit, vegetables, fresh eggs - all fine. Raw meat, lots of cooked foods - really dangerous.

So an extra, very plausible point of failure is particularly bad for refrigerators and freezers.

  • Cord Type/Quality

A good quality extension cord with a ground wire and large enough wires (at least 14 AWG) can handle 5A of load without any problem. But there are some really cheap "lamp extension cords" that have thinner wires (e.g., 16 AWG) and no ground wire. Even those should be OK with 5A, but of course there is nothing to prevent 15A (or 20A if there are multiple receptacles and used on a 20A circuit), so the cord itself can be overloaded relatively easily. And if the appliance has a ground wire and you use a 2-wire cord with a "cheater" you have more possible problems because the ground goes...nowhere.

Provide a separate circuit

This is where it gets interesting. Generally speaking there is no need for a separate circuit. I have a lot of stuff in my house on one circuit, including a refrigerator/freezer and separate freezer in the basement. I finally (or rather, my electrician did) separated things a bit so that the computer and laser printer are on as separate circuit from the refrigerator/freezer and freezer because I could see some interaction when different things powered up at the same time. But does each device really need its own separate circuit? Unless the instructions truly require it (not just "recommend") it, there is no electrical need for that, not with appliances that draw < 7A each (e.g., less than 1/2 of a 15A circuit). So sharing with lots of stuff is not such a great idea, but with some other stuff that doesn't have large power requirements is generally fine.

There is an additional consideration specifically for a refrigerator/freezer in a kitchen: GFCI. Generally speaking, nearly all 120V circuits in a kitchen require GFCI protection. About the only exception in the latest code is (I think) lighting circuits that don't have any receptacles in the food preparation area. But there is a concern that (a) some refrigerators have a tendency to cause GFCI trips (this should be less frequent with newer appliances designed in the GFCI era) and (b) an unnoticed GFCI trip on a circuit shared with the refrigerator can cause a serious food spoilage safety problem. A common solution to this is:

  • A separate single receptacle exclusively for the refrigerator. It might be on a separate circuit or it might be on another kitchen circuit but connected in a way that it does not have GFCI protection (e.g., split off the circuit prior to a GFCI/receptacle).
  • The receptacle is placed so that it is more than 6' away from all sinks.
  • The receptacle is not counted as part of required countertop receptacles.

Many jurisdictions and/or inspectors will allow this exception to a blanket "GFCI for everything in the kitchen" because of the concerns about food spoilage and being outside the letter of the law with respect to 6' from sinks and required countertop receptacles. Just keep in mind that some inspectors may insist on "everything in the kitchen must be GFCI" even though that is not strictly speaking the rule.

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  • 26
    Separate circuit has similar purpose: prevent accidental loss of power due to some other device tripping the breaker.
    – jpa
    Oct 29, 2023 at 12:07
  • 2
    When the motors start up, they may draw quite a bit of extra amperage for just a moment. If both start up at the same time, you could have a larger potential of tripping the breaker. Like others have mentioned, tripping the breaker leads to spoilage. Oct 29, 2023 at 21:34
  • 5
    Extension cord misuse is a known leading cause of fires in homes (see FEMA and NFPA websites), and given that appliances usually draw more current than other devices and people aren't generally aware of the wire size in their extension cords, it's clear that cord type is not just "plausible" but a well-known reason.
    – simpleuser
    Oct 30, 2023 at 4:29
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    A related issue: If/when you sell your house, if a major appliance is running on an extension cord, a house inspector may flag it for the potential buyer's attention (depending on local codes). If you're going to end up getting proper wiring put in for it, you might as well do it early and enjoy the benefits yourself.
    – LarsH
    Oct 30, 2023 at 12:45
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    The most important reason for not using an extension cord is that they are not UL approved for permanent use.
    – FreeMan
    Oct 30, 2023 at 14:48
6

The reason the instructions say to do those things is that most people do not have the understanding and do not apply the level of analysis that you have. If everybody freely uses extension cords and installs appliances on general circuits, there will be a lot more problems in the world, and the manufacturers will be blamed for most of them.

An undersized cord can cause a fire or, in a fridge/freezer, poor performance. A cord is an additional point of failure in an appliance that needs to be reliable even when unattended. A fridge/freezer on a shared circuit can fail if someone uses a vacuum, hair dryer, etc. None of these things would apply to you if the two devices share a circuit only with one another and any extension cord is properly sized and installed in a reliable manner. But the manufacturers cannot rely on all that, so that is why they use these labels.

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The extension cord prohibition is mostly for liability reasons. In your case, there's no reason for it beyond what manassehkatz said: tripping and unplugging. The refrigerator linked pulls 1.1 amps, which even the worst extension cord will support.

In most other cases, it's a case of not trusting the user to understand wiring.

I installed a point-of-use water heater that lists its draw at 14A. It wanted a 20A dedicated circuit (which I added) and no extension cords. That second one was impractical because of where I had to add the circuit (it was just too far for the cord to reach), so I added an extension cord (it's in the back of a cabinet so no tripping hazard) and it's been working fine ever since.

Extension cords generally come in three flavors:

Light Duty

These are generally your two-prong variety (there are some three-prong options here and there) that are 16 gauge and designed for use indoors only. Most will have three receptacles on the other end. These will run a lamp or just about anything that uses two prongs. The problem on 16 gauge is that the maximum rating for that is 13 amps. That covers a lot of things, but it doesn't cover anything that is using most of that 15A (things with heating elements like space heaters, hairdryers or irons)

Medium Duty

Now we're getting into your utility extension cords, such as those you would use outdoors. The big difference here is that those multiple-receptacle endings tend to go away. The catch here is most of these are still 16 gauge. That means you can only run 13A still. There are some variants that go to 14 and even 12 gauge, but they are much more expensive options than their 16 gauge cousins. You should assume any outdoor extension cord is 16 gauge unless you can directly verify it's got a higher gauge wire. Most people do not know to do this.

Heavy Duty

As mentioned, some outdoor extension cords are already sized appropriately. Now that you know what the gauges mean, you can shop smarter, looking for the higher gauge wire.

12 gauge extension cord

A minor note of caution here: a 12 gauge extension cord can handle 20A. Take care not to buy one with a 20A plug on it (one blade will be perpendicular to the other), or you will have to have a 20A receptacle to plug it into.

I didn't need an outdoor version, however, so I bought the indoor version. These are often marketed as an "appliance extension cord", or an "air conditioner extension cord". These are always 14 gauge or 12 gauge, and will handle a full 15A easily. I have one of these powering my 14A water heater

Appliance Extension Cord

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You don't want a fridge on an extension cord. The cord may be fine today. But it may be in the way, it gets moved now and then while scrubbing floors - maybe even stepped on. This wears it down, occasionally breaking a copper strand inside the insulation. 15 years later it overheats and starts a fire.

Extension cords are therefore not for permanent installations, especially not stuff that draws power while you sleep.

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  • Give you an up vote for making an answer of this. I just added it as a comment on the (currently) accepted answer.
    – FreeMan
    Oct 31, 2023 at 15:21
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If I use an extension chord for anything, I use short 2ft or 3ft extension chords with 12G OR 10G cable; electrical books that I have read says never use an extension chord longer than necessary, so I cut a 100ft 12g extension chord into various lengths so I use them according to the distance from the recept.It doesnt make sense using a 75ft or 100ft chord if the receptacle is only 5ft or 10ft away. I have seen workmen using a 100ft 14G chord with a circular saw for hours. I have some 2ft and 3ft 12G and 10G chords that I keep handy in case I need to plug something when the recept. is close by enough.

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It is a matter of amperage and wire gage. Low amperage and large wire gage ( # 14, or 12) = no problem. Portable equipment will often state a requirement such as 100ft max for #14. Small gage adds too much resistance for significant amperage. Tables are available.

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    The extra plugs often add much more resistance than the smaller wire. That's where most heat is generated.
    – isherwood
    Oct 30, 2023 at 19:32
  • @isherwood sure about that? Most of my extensions are 16/18awg. Not that I would use them for anything heavy, but folks don't know better. OTOH, youtube.com/watch?v=4cp28hIMP94 saw minor drops from hundreds of plugs in series.
    – dandavis
    Oct 31, 2023 at 4:36
  • Most grounded cords are 14 gauge, or at least 16. Everything I've learned is that it's the connections that add resistance, and my personal experience is that plugs get much hotter than the wire itself. Cable TV installers would tell you the same about their connectors. [Not my DV, BTW.]
    – isherwood
    Oct 31, 2023 at 14:45

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