Reasons for gate failure

    Reasons for gate failure

Do you have an automated gate that is not working?

Lets run down a few common causes and remedies before you call the gate doctor!

Author  ;   Huw Jones

First aid

I have been helping folk fix their gates for 30 years. Most old gate installations are fairly simple. There were fewer parts to go wrong, but the standards of installation were not what they are today. Old hardware was well made, durable, if not a bit basic.

Installations simce 2010 are more safety orientated, which makes them more sensitive to environmental changes. Some failures may be avoided by some simple maintenance like lubricating, garden control, pest control, waterproofing.

Look after your gate system and it will look after you. Your gate engineer is an expensive gardener.

Know your gate

It can be helpful if you know what you have. What brand, what model, and most pertinent, what control panel has been installed. Do you know what the purpose of each of the parts is.

Not all installations are the same. You should keep a file of gate information. Any gate installed in the last 15 years should have a data pack. Insist on that file when you buy a property with any automation system.

A few photos can be very useful for techncal support. We are blind without you. Have the photos ready, don't wait to be asked.

A bit of history

When was the last time the gate worked?

1. It has never worked, i am installing it for the first time
2. I got it working recently, but now it has stopped
3. It has been working for years. It stopped a day or so ago.
4. I moved in recently. I have never seen it working.
5. It is intermittant. Works some times, not always. 
6. It worked until we had a power cut.
7. It worked fine until ... we planted a tree / there was a lightning storm

1. Check the obvious

If the gate system has ever worked, the reason for it not working will be a small failure. You have to hope that a small failure did not lead to a more expensive breakdown.

Here are some obvious things to check first

• A blown fuse resulting in loss of power
• Water ingress has caused intermittant fail
• The gate or motor has been hit
• Overgrown foliage interfering with a sensor
• Broken surface wiring

Is the control panel warm? Does the photobeam click when blocked? Are the lights still on?

How many ways are there to open the gate? Is there an intercom, or keypad? is there sensor under the drive?Have you lost a remote recently? Is there a secret switch to open the gate?

1.  Visual inspection

A simple inspection will show if any thing has changed since the failure.

Look for a sagging gate, damaged or exposed wiring, loose hinge, flooding, road breakup, garden over-growth, leaf and debris build up, physical damage to motors or safety devices, scratch marks on a gate or ground  scraping.

Beneath the covers, there maybe an infestation of insects, mice, or slugs.

Extremes and changes in weather often prompt a failure (and recovery). Keep a note of rainfall, high winds, extreme cold, leaf 

2.  Substitution

Try a different remote. If only one remote works, 90% of the system is OK. Obvious, but shows the principle.  

Double leaf gates have a great advantage. If one leave is misbehaving, swap the motor wires around. If the problem stays on the same side, it is likely to be a controller issue, and if it switches sides, it is the motor or wiring.  

Keep spares. An old motor could be used to check the system function. 

3.  Elimination

If you cannot substitute, eliminate. Simplify the system by disconnecting may find the source of the problem Examples are;

Activation devices can cause gates to stay open, or act erratically. Devices like a keypad, intercom, exit button or loop can be dis-connected one by one until the fault stops. 

Safety devices often stop a gate functioning for safety. Disconnecting is not as simple; the safety contact needs to be bridged out.

Powered devices, locks, lights, or auxilliary power supplies maybe disconnected. 

It is tempting to call your gate guy to come and fix the gate, but it may be something simple. He will get to the problem quicker if you can help him out with some simple investigation. If he comes out and has to make a return trip witha replacement part, you will pay for both call outs.

1.

The gate won't open by remote.

There are many reasons for a gate not opening, and often more than one way to request an operation. Is there a LED lit on the remote (battery)? Do you have another remote you could try? Has the antenna been broken? Try the remote up close to the control panel. 

2.

One of the wired inputs doesn't work

The gate won't open by keypad or intercom or exit button or loop.

If the remote doesn't work, try to operate the gate on a wired input. These are devices like an intercom, or keypad, or a button, or vehicle detector. If one of these doesn't work but another does, it is likely to be a fault in one devices. 

If 2 or 3 wired devices don't work, there maybe a fault in the on of the devices that is jamming the wired input preventing the other from working.

3.

The gate won't open by remote (1) or by wired input (2).

If the remotes don't work, and nor do any of the wired devices, there maybe a device disabling the operation. Do you have a photobeam on the inside of the property? Are there any safety edges that would stop the gate opening for safety reasons? Check the photobeams by blocking them ( an LED normally changes in one part). Check any edges that prevent opening.

4.

The gate won't open.

Could the power have failed? Check for LED's on an intercom that are normally lit. Check the photobeams by blocking them ( an LED normally changes in one part or you hear a click). If there are no LED's visibly ON, feel the top of the control panel, which should be warm.

If there are none of the usual lights, and the control panel is cold, there may have been fuse failure in the control panel or the house supply has tripped.

5.

The gate opens but won't close automatically

Will it close if the remote is pressed again? This could be a freeze function, where the normal auto-closeis disabled when the remote button is pressed a second time.

Is the auto-close function enabled. If it worked before, but not now, it is unlikely to be a setting problem. Old analogue ZA3 controllers suffered from damp cables that causes a partial short on the OPEN input, thus stopping auto-close.

6.

The gate opens but won't close, even when given  automatically

Are the wired opening devices working? Check keypad or intercom LED's for abnormally lit. Check the wired button is not jammed in. A wired opening device may have failed locking the gate open.

Have you lost a remote? Could it be under a book so it is sending a constant signal? 

It could be a safety problem. Check the photobeams mounted the gate posts. Block the beam; an LED normally changes in one part, or you hear a click. Is there a safety edge that would prevent closing? Is there a hold open switch in the system,  on the intercom, or keypad, or radio receiver?

7.

The gate won't open or close, but makes a small jolt every time the remote is pressed.

One gate opens a foot then stops.

Control panels with encoders use the encoder pulse as feedback that the gate is running. If the encoder is damaged, or the encoder wire is damaged, the controller does not get the stream of pulses it is expecting, so it stops the run.

If one gate leaf opens a foot, it will be an encoder fault on the leaf that didn't move.

8.

The gate closes all the way, then re-opens. It tries again this time stays closed.

The gate closes all the way, then re-opens. It does this 3 times, then stays open.

This is likely to be a the obstacle detection kicking it. If a controller senses an obstacle, it will try 3 times, then give up. It may suceed, it which case it stays closed.

Get the gate serviced and check for resistance at the end of travel, as this is where the obstacle detection is most sensitive.

9.

The gate is running normally, then one gate stops.

The gate opens and closes randomly, then eventually, one gate  stops.

If one gate leaf is running and the other not, it is likely to be overheating. The 230Vac motors have a thermal trip inside. When a motor overheats, it shuts down to cool down. The fault may be a capacitor, or the gate needs servicing. 

If you turn up the torque to push harder, it will only overheat quicker. Better to lubricate, then reduce torque, or reduce over-run time. 

If the gate swings freely, but a motor always stops in the same place, there may be a gearbox failure that will need inspection. If the motor is changed, the encoders will need re-calibrating.

10.

The gate starts, then stops after a few seconds. The house's RCD trip has tripped out.

First, check that there are no other items wired into the RCD apart from the gate control box. It is tempting to blame the gate system, but often there are other mains lights or pumps on the circuit. 

When the total trip current reaches the limit, it is the last straw that exceeded the limit. RCD faults are covered in another article.  

11.

A ram gets part open, then sometimes stops. If it is manually moved past that point it still won't run.

This maybe a fault that has developed in the flexible cable running into the operator. It twists back and forward by 100 degrees, which can cause the wrong sort of cable to fracture inside.

Change the cable. It should be a flexible natural rubber cable. It helps to have the cable hang down loosely. Short cables twisting over a short distance fail quicker.

10 top reasons for failure

Electronics is pretty reliable, so why do gates have such a poor record of reliability?

It is probably the due to the environmental protection offered by the site. Experience will go a long way to preventing dome common faults. So will using low voltage openers. Read why.

The list below is in no particular order.

• Wiring faults
• Ingress
• physical damage
• product failure
• vibration & stress

1.

Sensor damage

Photobeams are easily damaged. Edges are soft and easily torn. Fortunately both faults are easily identified. They need to be functional for the gate to run.

2.

Power failure

Your gate installation should be protected by an RCD (residual current device) in the fuse box. 'Outdoors' is one of the three areas that are regulated by 'Part P' of the building regulations, essentially where power and water may cause risk of electric shocks. Openers with 230V motors may ingress moisture which could sum to a point when the RCD trip will disconnect. 

Low voltage motor sets are unlikely to trip if the 230V protected supply never leaves the control panel.

3.

Manual release

Manual releases may never be used until necessitated by an emergency.  But they need to be checked if they are to be relied on. They are close to the ground where road grit and road salt can seive up mechanisms with key release.  

4.

Cable failure

Cables fail for many reasons, but the solution is largely the same; the right cable for the job! Duct cables need to be duct grade, which is waterproof and high tension. Cables down ducts may also need to be rodent resistant. Surface cables should be ducted. Ram cables and cables crossing a hinge can be formed into pig tails that bend over the length of the spiral, not twist over a few inches. Cables not secured are at risk of catching in .  

5.

Setting stops & limits

Limit switches and slow down points need to be set properly. Correctly set, the gate will not slam or shake. Sliding gate stops will become loose allowing the gate to slam, which has  a knock on effect for reliability. Using lock nuts or thread lock will increase reliability. Soft rubber buffers absorb energy while closing the gap fully.

6.

Slugs

A slug will seek a safe space. They are exposed in open space. They will squeeze through narrow spaces like control panel ventilation grilles, then hide under the PCB, safe until you power up the motors .........            Slugs are the cause of countless PCB failures, and some fires, but they are easily deterred. 

7.

Drainage

An underground motor is usually IP67. That is not immersion proof. The motor casements need effective soakaways. If the motor runs submersed regularly water seeps in through the top bearing seal. It will eventually get into the motor, where 230V versions will start to trip the RCD.

8.

Light physical damage

Any collision needs to be checked over. The problem is what you don't see. A bent hinge or damaged wheel bearing may have knock on effects later. They can cause additional drag and vibration. Swing gate damage may also have caused damage to the drive chain or loosened protective coverings that will allow rain ingress. 

9.

Earthing & power surges

Any metal housing around mains power must be earthed. So why is it important to earth a low voltage motor or a metal gate? The motor cable is a direct line of conductivity to the control panel. If the gate, posts, exit loop, or ground around the gate catches a lightning strike it could get back to the controller and destroy it. Earthing supplies the shortest route. This destructive charge can also enter via the incoming supply. A steel wire armoured cable will help, but it must be properly earth bonded. 

10.

Vibration and shock

Mechanical stress comes from decelerating forces. Gates that are allowed to slam shake fixings in the opener, hinge fixings and wheel bearings. Over time, this can also loosen electrical connections and fracture single strand cable. Modern Low voltage control panels have greater adjustability of slow down at the beginning and end of travel. Better control reduces stress.

Automation safety standards limit pressure applied

What is an RCD or ELCB?

Residual Current Devices (RCD), or Earth Leakage Circuit Breakers (ELCB), are found in a fuse box. They look like a resettable fuse, but have a button marked 'test'. Their purpose is to protect mains circuits in vulnerable areas where insulation damage could render metalwork live. 

A 30mA RCD (0.03 amps) will protect a human from death by electricution. A  300mA RCD (0.3 amps) may be used for heavy equipment and fire protection. 

Some properties are covered by a single RCD trip. We advise the gate be on a separate parallel 30mA RCD so that any outdoor faults do not trip out the whole house.

How does it work?

In simple terms, all the power that flows out of the 'Live' terminal should flow back through the 'Neutral' terminal.  If there is an imbalance, some current is being lost somewhere else. Think of it like a water circulating around a pipe. A leak in the pipe will result in less water coming out of the pipe than went in. The RCD measures the difference between currrent through live and neutral. For more info, see ...

https://www.electricalsafetyfirst.org.uk/guidance/safety-around-the-home/rcds-explained/ 

RCD's on an electric gate

Your gate system should use a dedicated 30mA RCD. You first need to know what else is connected to the gate RCD. Too many times, the RCD also supplies outdoor lighting, pool pumps, electric vehicle chargers, CCTV and intercoms. Worst case, it trips out the whole house! Press the test button to kill the power, then check what else has been cut off. 

The RCD only trips on mains powered loads. Gate system controllers for 230Vac motors generally isolate the motor Live and Neutral feeds until the motor is required to run. If there is a current leakage fault in the motor or mains flashing light or courtesy lights, the breaker will not trip until the motor tries to run.  The control panel and intercom supplies are connected all the time. There may also be timed lighting. 

The RCD can be positioned in gate control panel, or in a nearby waterprrof enclosure. The supply cable up to the RCD should be suitably protected if not under RCD protection, and the supply must be fused.

Isolating the problem

It is easier if your gate system is protected by a dedicated 30mA RCD. The RCD trips on a total leakage of 30mA contributed by all the items on that circuit. Too many times, the RCD also supplies outdoor lighting, pool pumps, electric vehicle chargers, CCTV and intercoms. Worst case, it trips out the whole house! 

You first need to know what else is connected to the gate RCD.  Press the test button to kill the power, then check what else has been cut off. Isolate all but the gate, then see if the RCD trips when the gate motors are run. If not, the gate system failure is not a single fault, but an accumulation of leakage.

If a double leaf gate trips the RCD at the point of run, disconnect each motor in turn at the control panel. If each motor runs on its own, the fault is an accumulation of leakages. Remember, all the wiring up to the motor is included in the test.

One motor might be directly connected, but the far side motor will have a junction box in between the motor and the control panel. Locate the connection, disconnect the motor, and try the test again. If you can't find the junction, it maybe underground, and there lies your problem.

Sloppy installers sometimes leave the junction box in the underground motor casement that often causes problems. There are gel filled connector box products that make promises to the gullible. The installer forgets that the IP rating needs to allow for changes in air pressure. The air in the motor heats and cools causing pressure changes that can suck water in over time.