The story of having a driveway gate opening unwanted with an exit sensor is not an unusual one. Exit wands are very popular devices for driveway gate openers (technically exit loops are what are popular but the installation and cost of a loop is prohibitive and thus people gravitate to exit sensors) but they are susceptible to many issues because of the nature of how they work. Some people even have properties that cannot utilize them because of soil or other issues.
Here is why they are problematic. To start, loops / loop detectors are what you find at stop lights and commercial exits. A loop is a twisted wire in the shape of a rectangle that is saw cut into the driveway that is energized by a loop detector. It uses induction to detect metal directly above it. This is a very reliable way to detect metal and typically does not pick up anything that is not directly above it since it is actually detecting metal. An exit sensor, since being buried in the ground next to the driveway for easy installation cannot work the same way. It instead needs to detect metal that moves into an area near it. Hence it is not a metal detector like a loop, it is a magnetometer. A magnetometer detects disruptions in the magnetic field. This means during times of not being triggered the magnetic field near the wand needs to be still and constant. Movement in the magnetic field are much like ripples in water and this is what the magnetometer detects. And this is where problems come in. If you imagine there are so many things that can cause ripples on water and the same goes for the magnetic field. You may ask yourself at this point why anyone sells these devices. The reason is although you will have some unintentional openings at times, for a majority of people saw cutting a driveway is out of the question and they, like you, have a very strong need for automatic exiting. This is the residential alternative to a loop to have this auto-exiting feature without the difficult installation. Typically there will always be random openings with a wand but they wont disrupt the gate opener’s functionality, it will simply open and then close during a storm or when a dump truck drive by too fast, etc, and the user hardly notices. But then there are cases where it is not random openings, it is constant openings and that is what needs to be figured out.
Here are the possibilities including defective product and test/solution for such.
Encasing the exit wand in conduit: Even better if you use some Styrofoam to center the wand in the casing so it is not touching the edges. Only the wand itself is what would be placed in conduit, the cost would be very minimal. The purpose of this is not to seal up the exit sensor, the exit sensor is already sealed. The point is to move it further from the soil and water. There are two issues this can help correct – ground water and iron ore. Ground water can carry an electrical charge that can cause interruptions in the magnetic field. Iron ore is found in soil in many areas of our country and can also play havoc on the magnetic field. However both of these are very light disturbances. One other thing of note on magnetometers is the larger the mass disturbing the magnetic field the further from the wand that the disturbance can be detected. Since these are both very slight disturbances encasing the wand in PVC (and centering it if possible) can sometimes move it far enough away from ground water and iron ore to solve the issue. Typically people that have an issue where the wand works above ground and then they bury it and it doesn’t work can be solved with this solution. So if you un-bury the wand and leave it above ground on the grass and it seems to be working better then this is probably a valid solution (not always a guarantee but still a good indicator because the grass and the soil the grass is in (typically not the same as the soil under the sod) is insulating the wand from the soil and ground water like the conduit would) One thing to be aware of with leaving it above ground, direct sunlight can produce a lot of heat and can cause the exit wand to trigger, so this would never be a permanent solution leaving it above ground.
Burying it deeper: This is only locating the wand itself deeper, not the wire, so you would only dig a hole that is at max 24 inches deep by about 3 inches wide and 36 inches long (length would be so you could loosen up on the incoming wire to allow some excess to be used to make the wand deeper than the wire itself (essentially the wand would be a few inches closer to the gate to acquire the extra wire to go deeper without digging up all the wire). This is in-case there is something near by that is causing problems. 120VAC line, sprinkler conduit (because of the water inside the line, not the pvc conduit itself), cell tower, fencing with metal, and other things can cause issue and by burying it deeper it will help insulate it from that disturbance. We can tell you exactly what would be correct for depth is is we don’t know the disturbance, the mass of the disturbance, location, etc there is no way to predict how far you have to move it away from the disturbance. 10-12 inches is the suggested depth for ideal conditions, but if the conditions are not ideal it comes down to trial and error.
Change the location of power supply to the wand: The wire itself is shielded to help defer electric disturbances. Most have the positive power lead of the exit sensor going to the gate opener control board accessory power terminal and have both the negative wire and the shield material of the wand going to the gate opener control board accessory ground terminal. The shield of the wire works when connected to a ground, which the board has a ground but not a great one (a good ground is not having resistance, the board has some resistance). So, one possibility is to take the power wires and shield and connect the directly to the battery instead. The ground of the battery is a much better ground than the board’s ground. Sometimes moving the wires to the battery directly along with the shield will help to ground the wand and solve issues. Lastly the best powering solution, if feasible, is to have the power leads going to the battery and the shield going to a grounding rod that is located at the gate. This provides the best possible ground for the wand.
Defective wand: This is always a possibility and has been seen before. But I would say interference is more common than this. The reason we don’t jump to this before suggesting the other stuff is this is actually the most labor intensive solution. The suggestions above your digging is only located at the wand itself. This is the one solution where you will indeed need to retrench the entire distance because you will need to bury the replacement wand and its wire the entire length. And it unfortunately has happened a few times where the wand is exchanged and either instantly or within a week or two the problem is back. By then the customer is usually over the idea of an exit wand or troubleshooting because of the labor involved in the exchange and is now digging the entire length a third time to take it up and return it for a different type of exit device. If you are exchanging consider swapping brands so if you bury a wand of a different brand and it is still malfunctioning you can be certain that the odds of two different manufacturers producing a wand and both of them being defective is non-existent and you have your answer about the possibility of being able to use an exit wand on your property.
Which brings me to what to do if your property is just not right for an exit sensor or after reading this you realize that an exit sensor may bring down the reliability of your system overall and you don’t want to have that question hanging over the gate of when the wand is going to randomly open the gate again (but again, typically exit wand usage when there is no constant interference just have random openings from things like storms or speeding dump trucks but then the gate automatically closes again so it is hardly noticed).
1. You could use a photo eye. It is not ideal as an exiting device because anything that blocks the path of the photoeye will trigger the gate to open, human, animal, build up of leaves, kid knocks the photo eye out of alignment by hitting it with a soccer ball, etc. The positive thing however about a photo eye is you can see what is happening, it is not invisible reactions to a magnetic field, it is a physical obstruction.
2. You could install a loop and loop detector. This is a commitment to doing the labor of installation but once installed the buried part is simply twisted wire set into a casing, nothing can happen to it really, if there was a problem it would be in the detector which is at the board. And since it detects metal rather than interference in the magnetic field it is much more reliable. (commercial applications like apt complexes, stop lights, office parks, etc only use loops, never wands)
3. Non-automatic device such as a push button on a post. If you mounted a simple push button anyone leaving could roll down their window and press the button if they didn’t have a remote.