Using Indoor Extension Cords outdoors

[Macrosill]

This topic seems to come up often, to say the least. I thought I would tackle this for everyone to read.

Let me start off by saying this, most extension cords are rated for "temporary use, less than 30 days" regardless if they are indoor or outdoor cords. The indoor cords we usually refer to are the spt, 2 conductor, molded plug type in white or brown. These cords are rated indoors for a few reasons. The first is because the female socket molded on the end of the cord in a triple tap configuration is not "rain tight", usually plastic. Another reason is the cable construction itself. These 2 conductor cords are made in the SPT style. This means there are 2 conductors with each only having its single layer of insulation, and lay side by side. This single layer of insulation makes the conductors much more suseptable to physical damage. Now an "outdoor" cord consists of 3 conductors, hot, neutral and ground. It also has its 3 conductors inside a cable jacket, the outer insulation that is usually orange. Now this cord is raintight in and of itself as they have rubber molded ends with only a single female socket.

The following is for informational purposes only. Do not use indoor rated cords outdoors. If you do it is at your own risk and the auther can not be held responsible.

I use the indoor cords outside for the Christmas season each and every year. As a matter of fact I have over 200 of these cords. I do not tape the connections either. I usually just leave the connections open to the weather, although I do elevate them off the ground to prevent them from sitting in puddles. I do not tape or bag the connections because water will inevitable find it way in either by rain or condensation. If you wanted to you could place a ziplock bag over the connection and secure it with a rubberband, leaving it open at the bottom to allow air circulation.

[ErnieHorning]

I don’t think I would agree that any extension cord is rain tight. Though the outdoor type usually has a silicone type molded outlet, it isn’t fused to the cord. If you hold the outlet and pull on the cord, you’ll see that it separates easily. Some cords are better than others, but the orange ones that most people are using will separate easily. This only helps protect the wires inside anyway but doesn’t protect the outlet side. Pour a bit of lightly salted water on a connection protected by a GFI if you don’t agree. Usually silicone repels water when new, which helps initially but it eventually doesn’t.

I don’t know if I would agree that a ground wire makes it outdoor either. The ground is there to protect people in case a metal case or cabinet gets shorted to the hot side of power. I don’t know of any Christmas decorations that take advantage of this ground.

I don’t cover any of my cord connections but I do elevate those on the ground. I don’t find that rain water is very conductive but water on the ground will pick up iron, salt and various other minerals and is very conductive.

I do cover my SSR’s because I don’t want water puddling inside the outlet box. I forgot about two SSR boxes last year and they filled with water. All it did was supply gate current to the TRIAC’s and they just stayed on. I dried them out and they worked fine. Although Hot and Neutral were standing in water, the GFI didn’t trip (because it was just rain water).

[jderba]

Thanks guys, this is good information. I've been meaning to do some research on the SPT-2 wire to see how well it would work outside, but haven't found the time yet.

Thanks again for starting this thread Brian, I think it will answer questions for a lot of people.

Jack

[Macrosill]

snip

I do cover my SSR’s because I don’t want water puddling inside the outlet box. I forgot about two SSR boxes last year and they filled with water. All it did was supply gate current to the TRIAC’s and they just stayed on. I dried them out and they worked fine. Although Hot and Neutral were standing in water, the GFI didn’t trip (because it was just rain water).

Ernie,
I see we disagree on a few points here. Thats ok, everyone has their opinion whether right or wrong. Everyone must choose what it is they feel comfortable with.

Before I start I would like to let everyone know the extent of my electrical knowledge. I started my electrical career back in 1989, while in High School. I had received 2 years of electrical instruction. After graduation I had gone to work for a private contractor doing electrical construction. After that I joined IBEW Local Union #25, located in Happauge, NY. There I rose the ranks so to speak until I reached the level of "A" Mechanic, the highest level there is. I had performed the role of Job Site Supervisor on a housing development consisting of 137 private single family homes with an average living space of 4,000 feet. I was responsible for the electric, cable and phone systems from the street curb up to and throughout the unit. One of the larger services I have installed was 400 amps and it consisted of 6 circuit breaker panels. That was supplied by 500mcm cable. That is a single cable that is as thick as your lower arm. I have left the union back in 1999 for a better career but I still am active in the electrical trade. I have continued my education in local colleges by attending advanced shools about electrical construction. I meet the requirements to hold a Master Electricians License in any county in NY State. I hold a Limited Electricians License in Suffolk County, NY and a NYS Security Technicians License for installation and maintenance of fire alarms, burglary alarms, cctv systems and access control systems. I am currently employed in a technical services unit of the PD that deals with wired and wireless surveilance. I just want who ever reads this to understand the extens of my electrical background and knowledge.

I would like to discuss this last point of your post, I quoted it above. I would ask what material your ssr enclosure was made of. If it was metal was it in contact with a circuit ground or the ground? If it was plastic was there any conductive material that was in contact with a circuit ground or the ground? The reason I ask is because you stated the GFCI did not trip because it was wet with rainwater. The way a GFCI works is it monitors the amount of current being utilized in the hot side and how much is coming back on the neutral side. If the ssr puddle was isolated from a circuit ground or the ground then the GFCI would not trip even if it was well water or any other kind of water. This condition would be know as a short not a ground fault. If the short was not sufficient to allow enough current to be conducted through the minerals in the water, then the breaker would not trip, overcurrent protection. For a GFCI to trip you would need current to go out on the hot and not return through the neutral, as in a ground fault.

[stempile]

*Duplicate Post* See

http://www.christmasinshirley.com/forum/viewtopic.php?t=297&highlight=

---

This is what I do. Works great and is cheap due to the buy in bulk price.

http://computerchristmas.com/index.php?link=how_to&HowToId=94

Good Luck.

[ErnieHorning]

I would like to discuss this last point of your post...
Not that this matters; I started my electrical career in 1977 when I received my first certificate, though the majority of my background is more on the low voltage electronic side, I’ve had to deal with the high voltage side occasionally also. The laws still apply in either case.

The box that I was using was plastic and even though it was lying on the ground, it had no direct contact with earth. Two quad boxes were nearly full of rain water, so the water was in direct contact with Hot, Neutral and circuit common. My controller was still isolated by a transformer and so was the notebook PC that it was connected to. Though the conducted current was low, the voltage probably would have still been high enough to kill one or both if not for the isolation. The GFCI was the same one that is connected to all of my outside power. It does work because I’ve had it trip when the outside light fixtures collect enough bugs that will conduct enough current.

Are you disagreeing that rain water is not very conductive? Though it’s not as pure as distilled water, it’s created similarly and the majority of the impurities are collected when it falls. Even so, its conductive properties are still close to distilled water until it comes in contact with something on the ground.

[Macrosill]

Ernie,
I am not arguing the point of rainwater conductivity. Water in and of itself does not conduct electricity, it is the minerals in the water that are conductive. I am bringing attention to your statement that the gfci did not trip because the ssr box was filled with rainwater. As I outlined in my previous post a ground fault condition would need to occur for the GFCI to trip. In the scenario you outlined there was no ground fault condition. What you outlined is know as a short. A direct path for electricity to move between the hot and neutral.

We should be bringing safety to these discussions and thus the true way these safety devices work should be brought out. A misconception as to how a GFCI device works could allow it to be used in an unintended situation thus providing no protection at all.

[ErnieHorning]

OK Brian, now I see the confusion. I do understand how GFCI’s work and I guess that I was typing fewer words than I was thinking. Yes a plastic box with even salt water in it with a hot and neutral wire inside would not cause a ground fault because there is no path from either wire to earth ground. I was thinking of when it was still raining. The box was full of water and was flowing over the edge. The water, had it been conductive would have still occasionally provided a path for current and the GFCI would have tripped.

I guess that I was thinking of some previous discussions where some people would believe that if a connection got wet that it would cause the CFCI to trip, which is not necessarily so.

Now that you mentioned it though, I think GFCI operation would be a good topic to add to the Wiki.

[buck]

A gfci does not need a grounding conductor to function correctly, the grounding conductor is for equipment ground only.
A gfci utilizes a differential transformer to determine if the hot and the return path ( neutral, grounded conductor ) are equal. If not that constitutes a ground fault. Therefore any current that is not returned through the neutral is a ground fault.
Be it Rainwater ,distilled water, or holy water, if it surpasses the current threshold of the differential transformer the gfci will trip.
There is no gfci response between the hot in neutral, until the circuit breaker trip point, when a breaker trips, otherwise A gfci would trip at any minor load.
A gfci will trip if there is a fault between the grounding conductor( equipment ground) in the neutral (grounded conductor)

[Rocket]

I live in Australia and our power distribution is a little different to what you are using.

If i understand correctly Ernie you say you are useing an isolation transformer so for your GFCI (or what we call an RCD) to trip the fault would have to be on the primary side of the isolation transforer. You should be able to ground either side of your isolation transformer without tripping the GFCI.

Of course or safety reasons neither side of the isolation transformer should be grounded else it defeats the purpose.

Rod

[Dan Ross]

How does a GFCI outlet work?


That outlet is called a ground-fault circuit interrupter (GFCI). It's there to protect people from electrical shock, so it is completely different from a fuse.

The question on appliance plugs talks about fuses. The idea behind a fuse is to protect a house from an electrical fire. If the hot wire were to accidentally touch the neutral wire for some reason (say, because a mouse chews through the insulation, or someone drives a nail through the wire while hanging a picture, or the vacuum cleaner sucks up an outlet cord and cuts it), an incredible amount of current will flow through the circuit and start heating it up like one of the coils in a toaster. The fuse heats up faster than the wire and burns out before the wire can start a fire.

A GFCI is much more subtle. When you look at a normal 120-volt outlet in the United States, there are two vertical slots and then a round hole centered below them. The left slot is slightly larger than the right. The left slot is called "neutral," the right slot is called "hot" and the hole below them is called "ground." If an appliance is working properly, all electricity that the appliance uses will flow from hot to neutral. A GFCI monitors the amount of current flowing from hot to neutral. If there is any imbalance, it trips the circuit. It is able to sense a mismatch as small as 4 or 5 milliamps, and it can react as quickly as one-thirtieth of a second.

So let's say you are outside with your power drill and it is raining. You are standing on the ground, and since the drill is wet there is a path from the hot wire inside the drill through you to ground (see How Power Distribution Grids Work for details on grounding). If electricity flows from hot to ground through you, it could be fatal. The GFCI can sense the current flowing through you because not all of the current is flowing from hot to neutral as it expects -- some of it is flowing through you to ground. As soon as the GFCI senses that, it trips the circuit and cuts off the electricity.


http://home.howstuffworks.com/question117.htm