I know it's wrong, but why?

[sepefrio]

I know you can't use an extension cord with a garage door opener. By my question is why is that the rule? The only thing I could guess, Johnny takes the extension cord for a minute to operate his bench light to work on the car. The car catches fire, Johnny starts pounding on the garage door remote but (since no power) it won't open. Poor Johnny.

Is it that simple? Or is there another reason?

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[Bill Kibbel]

1. NEC sez so.

2. Most (maybe all) manufacturer's instructions specifically state not to use an extension cord.

3. I'm guessing it's at least partly due to the possibility of excess cord, not fastened properly, falling loose and becoming damaged by the working parts of the opener.

[John Dirks Jr]

I'll take a stab at it.

Extension cords are considered flexible because they are made with stranded wire. The stranded wires are not able to carry as much load as solid wires of the same size. Many cords may look heavy enough but in fact are not.

The danger is that a home owner will use an extension cord that is not capable of carrying the load. Components of the door opener can over heat and burn if a capable load is not delivered to it during its attempted work cycle.

The manufacturers of the openers know that most solid household wiring is capable of delivering the load. They won't place that bet on all the extension cords on the market.

[Richard Moore]

John C.

I think you only have to look at your photo and realize that what should be used as a temporary extension for a portable appliance has now become "permanent" wiring for a fixed appliance. Even if the extension cord is sized correctly (and that is probably OK), would you allow that permanent "wiring method" anywhere else in the home?

Would it be OK to substitute the extension cord with romex wrapped around the track support with a receptacle in a J-box on the end, dangling from the ceiling? Of course not. How many wraps around a track support are allowed for an extension cord? How would you regulate the way a "permanent" extension cord is routed, supported, protected, etc, etc. If it's OK in the garage then can I use one for my fridge, washing machine, etc, etc.

Will the one in your photo ever cause a problem? Maybe, maybe not. But there is no doubt that it is less safe than a properly located receptacle, connected with an approved wiring method, allowing a direct plug-in. So why fight it?

[sepefrio]

Rich,

Not fighting it, was actually looking for an answer to the home owner when he said "Why is that wrong?"

Like Bill said above I told him it was against NEC and then he said "why?". Then the sellers agent said it should be grandfathered. I replied it wasn't grandfathered and again it's against NEC.

So I do know it's wrong, not fighting it, I'm just looking for more of the answers to the questions that come up. Although correct, I think that by replying with simply "It's against NEC" I'm not really answering his question as he (A Navy Chief) probably is wondering what the Navy Enlisted Classification has to do with it. [:-slaphap

[Richard Moore]

"Then the sellers agent said it should be grandfathered..."

LOL...that opener looks very new, say 10 years old at most. Any "grandfathering" (cough...BS) ended when they installed it.

[Chad Fabry]

The stranded wires are not able to carry as much load as solid wires of the same size.

That's a good guess but it's not accurate.

[Jerry Simon]

Think grounding...

[Brandon Chew]

The short answer to John's question is that there is an increased risk of fire or electrocution when an extension cord is used where the code requires permanent wiring.

We can't build houses or electrical systems that are risk free. We can reduce risk but it comes at a cost. At some point there is a balance between cost and acceptable levels of risk. That balance point shifts over time due to changes in technology, costs, and social perceptions of acceptable risk. In this case, a nationwide panel of subject matter experts determined a long time ago that temporary wiring methods carried higher risks; risks that could be lowered at a reasonable expense by using a permanent wiring method. In other words, it won't cost a lot to do it right -- extend a branch circuit and install a j-box and receptacle -- and doing it right will lower risk.

The hazard with using an extension cord, a temporary wiring method, lies in its very nature. It's temporary. That means it is easily moved or removed. So while the cord that is there today might be sized OK, routed OK, supported OK, and be in good condition, those conditions could be easily changed in the future.

Joe Homeowner decides some day that he needs that nice heavy duty cord for something else. He replaces it with a low quality, low ampacity, two conductor, indoor cord. Or he borrows that cord, and when he puts it back, he wraps it a little too tightly around the sharp angled steel door track or motor support. Or he gets tired of the cord getting in the way of him taking that big box down from the shelf, so he decides to staple it to the ceiling, and in the process he pinches the conductors or damages the insulation on the extension cord. Maybe some day the loose end of that cord (outside the photo), for whatever reason, lands against the hot muffler of the lawn tractor parked in the garage ....

Originally posted by inspecthistoric

1. NEC sez so.

2. Most (maybe all) manufacturer's instructions specifically state not to use an extension cord.

3. I'm guessing it's at least partly due to the possibility of excess cord, not fastened properly, falling loose and becoming damaged by the working parts of the opener.

I'm guessing that #2 is because of #1 and the fact that there are many installations that are like John's photo. They've identified a common installation error and are trying to say in plain English: "Don't do it."

[Billy_Bob]

The NEC exists because of accidents which have happened in the past causing loss to life and property.

Say you have one of those nightclub fires caused by an electrical problem and many people die. Or a house burns down and children die.. Well there is a big public outcry to "do something" about this to prevent these things from happening in the future.

They learn what caused the problem and change the electrical code to hopefully prevent these accidents from happening in the future.

With that said, many fires have been caused by extention cords! You have homeowners who know nothing about electricity installing these extention cords, whereas you have trained electricians installing outlets and home wiring.

Well modern electrical design attempts to design things so that the use of extention cords will not be necessary. Outlets everywhere needed. That is the basic idea. Keep 'em from using any extention cords as much as possible and this will save lives.

[mthomas1]

For starters, anything that potentially compromises the grounding of a garage opener is a Bad Idea: if there is a fault at the opener you can energize the tracks... and the door.

For an example of the bizarre stuff that can actually happen, consider this example of a

when a series of wiring mistakes not only eliminated the EGC, but actually energized it!

A defective cord, or one without a ground, or a cord with the grounding prong removed or broken off like these two (which both happen be sitting... in a garage) would compromise the ground and could result in an energized the door assembly which failed to trip a breaker if there was a wiring or equipment fault at the opener/light.

[Richard Saunders]

Originally posted by mthomas1

For an example of the bizarre stuff that can actually happen, consider this example of a

when a series of wiring mistakes not only eliminated the EGC, but actually energized it!

A defective cord, or one without a ground, or a cord with the grounding prong removed or broken off like these two (which both happen be sitting... in a garage) would compromise the ground and could result in an energized the door assembly which failed to trip a breaker if there was a wiring or equipment fault at the opener/light.

I don't think there was an extension cord involved in this incident which completely blows your theory of why permanent wiring is better. At least with an extension cord wou can see if the ground prong is missing. Why not just ban extension cords period if they are so hazardous?

You will have a hard time convincing me that a grounded extension cord plugged into a GFCI protected outlet is unsafe.

[Jerry Simon]

Originally posted by Richard Saunders

Originally posted by mthomas1

For an example of the bizarre stuff that can actually happen, consider this example of a

when a series of wiring mistakes not only eliminated the EGC, but actually energized it!

A defective cord, or one without a ground, or a cord with the grounding prong removed or broken off like these two (which both happen be sitting... in a garage) would compromise the ground and could result in an energized the door assembly which failed to trip a breaker if there was a wiring or equipment fault at the opener/light.

I don't think there was an extension cord involved in this incident which completely blows your theory of why permanent wiring is better. At least with an extension cord wou can see if the ground prong is missing. Why not just ban extension cords period if they are so hazardous?

You will have a hard time convincing me that a grounded extension cord plugged into a GFCI protected outlet is unsafe.

Richard,

I've seen hundreds of garage door openers plugged into two-wire extension cords that are themselves plugged-into non-GFCI receptacles, and the risk of shock is thereby increased. This is certainly one reason, of a few, why extension cords are not permitted to be used for such application.

Joe The Homeowner does all sorts of stupid stuff - we all know that - and one such is doing the above.

[Richard Saunders]

"I've seen hundreds of garage door openers plugged into two-wire extension cords that are themselves plugged-into non-GFCI receptacles"

I agree, that would be wrong, and I also would call out the installation in the picture. But suppose the cord was a 2 foot heavy duty appliance cord because the receptacle was a bit out of reach?

I like the "against the NEC" - "Trip and Fall" - "get tangled in the mechanism" theories better than the possible lack of grounding. Any appliance can be potentially ungrounded whether on an extension cord or not. It's kind of suprising that garage door openers are even allowed to be plugged in. Doesn't that violate the unattended appliance rule?

[Billy_Bob]

Originally posted by mthomas1

...For an example of the bizarre stuff that can actually happen, consider this example of a

when a series of wiring mistakes not only eliminated the EGC, but actually energized it! ...

Wow! I was thinking "homeowner wiring" of something like a garage door opener would be pretty harmless. But now that I think about those metal doors, I will look at this differently from now on.

Anyway that is what codes are for. There is always some tragic reason behind each rule.

[msteger]

Whenever I see extension cords, I note to the client (and in the report) that extension cords are meant as temporary wiring and can present a fire hazard. I also recommend to the client that a licensed electrician be consulted to install additional grounded receptacle(s) where needed to minimize the need for extension cords.

BTW.. one of the funniest things I've ever seen was a seller who had a Belkin surge protector sitting on top of a front yard bush so she could plug in her Christmas lights. I had to just laugh at that one..

[SonOfSwamp]

A little Googling of "extension cord safety" spit out this:

http://ulstandardsinfonet.ul.com/stp/ad ... %80%A6.pdf

WJ

[Sodapop]

I don't think there was an extension cord involved in this incident which completely blows your theory of why permanent wiring is better. At least with an extension cord wou can see if the ground prong is missing. Why not just ban extension cords period if they are so hazardous?

You will have a hard time convincing me that a grounded extension cord plugged into a GFCI protected outlet is unsafe.

Try using a 16AWG extension cord, which is rated for 10 amps with a Skillsaw 13-15 amps.

Fact is: Drawing more current on a wire that can't carry that current is UNSAFE

Anyway: Extension cords are for Temporary Use and are not listed and labeled for use to supply garage door openers.

[Richard Saunders]

Originally posted by Sodapop

Fact is: Drawing more current on a wire that can't carry that current is UNSAFE

Very true! I wonder how many amps a garage door opener draws?

Anyway: Extension cords are for Temporary Use and are not listed and labeled for use to supply garage door openers.

I've never seen a listing or label on any extension cord, except the wire gauge. I guess you can only use them for things that are on the label? That would narrow the list!

[mthomas1]

From SoS's link:

"Children are generally less knowledgeable about electrical products and their associated hazards than adults."

From this afternoon's inspection:

From Albert Einstein:

"The difference between stupidity and genius is that genius has its limits."

[Sodapop]

I've never seen a listing or label on any extension cord, except the wire gauge. I guess you can only use them for things that are on the label? That would narrow the list!

If it has UL, or another approved testing facility, on the label it is LISTED and LABELED.