Gate motors

[Derlyn]

Does a low voltage gate motor need an isolator?

[Thys LOW Elektries]

As far as I know is the purpose of the isolator at a gate motor firstly to disable the power when you need to work on the motor and secondly to disable power in the cable when there is no motor present so that you don't have open and live wires.
I have seen plenty gate motors with no Iso present, not legal but they are there.
I'm not sure what your setup is like though.
Maybe install a waterproof plug for the motor? You can unplug it to work on it or when you have to remove it. Just a suggestion

Greetings

[Derlyn]

There's 14.7V supply to gate motor.

[Derlyn]

it's an extra low voltage unit fed by a plug in transformer in the garage. Transformer is 14,7 V. Must there still be an isolator at the motor.

i know there MUST be an isolator for a 230v gate motor. Just not sure if it is mandatory if the supply is 14,7v. That's actually my query.

[Thys LOW Elektries]

I believe that if the transformer is running through a plug, it is sufficient. Plugs and Iso's work on 230V. So getting something that can handle 15V may be expensive and difficult.

I won't bother with an Iso

Greetings

[Tradie]

Common sense would tell me to fit some form of isolator at the gate, in case you need to remove it. Make sure the volt is within specs, to prevent challenges with the charger.

The voltage is too low to worry about SANS.

The motors we work with have a removable plug on the motor.

It is very common for a gate people to fit the transformer in the garage or house, which allows them to install the cables together in the same conduit as the comms cable.

If you run a 230 VAC supply to the gate, then you cant install the cables in the same conduit if the comms cable insulation is not rated for the mains power.

[Derlyn]

" the voltage is too low to worry about SANS"

Tht's what I needed to know. Doing a COC inspection and wasn't sure whether I should include fitting an isolator.

I'll give it a miss.
Thanks.

[Tradie]

Make sure the gate transformer is plugged into the socket outlet and not wired into the electrical installations.

[GCE]

The voltage is too low to worry about SANS.

r.

Don't agree with that statement

SANS10142-1
Introduction
In this edition an attempt has been made to move towards the IEC codes:
extra low voltage (below 50 V) and d.c. applications (up to 1,5 kV) have been
introduced as new requirements owing to the extensive usage of, and
increased fire risk that result from, high load currents. This part of
SANS 10142 does not intend to cover the LV control circuits of machinery or
system components that are external circuits between separately installed
parts of the machinery or system components.

[GCE]

Does a low voltage gate motor need an isolator?

Don't think it is str forward - saw the question , was having a think on it - went and read a bit and now more confused as to what is right or wrong

There are various sections that deal with low voltage and DC and there is not voltage specified under motor .

I look at your problem and ask , what happens if the motor stops working 3 days after signing the COC and they come back to me because the twin flex under the ground is damaged or volt drop is to much and not charging the battery sufficiently - How to I justify leaving it off the COC and ignoring that fact that it does not feel right by ignoring.

I would put a socket outlet at the gate and plug the transformer in - Let the present owner pay for that now rather then I pay for it later with the new owner .


[B]5.8 Extra low voltage systems (SELV and PELV)[/B]
5.8.1 Shock hazard protection by extra low voltage
5.8.1.1 Protection by extra low voltage is a protective measure that consists
of the following two different extra low voltage systems:
a) SELV (safety extra low voltage), an unearthed system; and
b) PELV (protected extra low voltage), an earthed system.

6.16.5 Motors
NOTE Motors include the motors in automatic doors and gates, garbage disposal
units, pumps (pool, fountain, spa, etc.), and the like (see also 6.16.1)

6.16.5.1.4 Each motor shall be supplied by a manually operated disconnector
or any other manually operated disconnecting arrangement such as a
withdrawable circuit-breaker, a removable link, a fuse or by the removal of a
plug from a socket-outlet, which provides at least the same isolating distance,
for the sake of safety, as a disconnector that is
a) readily accessible and mounted on or next to the motor, or
b) visible from the motor, or
c) lockable in the open position, or
d) housed in a lockable enclosure other than a distribution board.

7.15.1 Selection of equipment and circuits
7.15.1.1 All equipment and protection devices in d.c. installations shall be
specified to operate on the specific d.c. voltages and shall be suitably rated.

[Derlyn]

Thanks for that GCE. Noted.

Decided to also do some reading and found this.

1.3 Where this part of SANS 10142 is NOT applicable.

h) extra low voltage control circuits between different parts of machinery or system components, forming a unit, that are separately installed and derived from an
independent source or an isolating transformer ( excluding EL V lighting circuits. )

Don't know if I'm interpreting this correctly, but from the above it seems to me that ELV circuitry supplied from an isolating transformer is not applicable to this part of SANS 10142. That would include my gate motor that is supplied from an ELV transformer.

It specifically excludes ELV lighting only, so down light circuits are included in SANS 10142.

Any comment ?

[Tradie]

All the motors we work with have removeable plugs on the PCB for the PCB power and motor. The 230/12 or 24 transformer is built in to the gate housing, so we install a sub DB on the wall next to the gate motor with a combo breaker for the motor and a combo breaker for any lights in close proximity and the sub DB is fed from an ELU.

From my understanding you dont have 230 VAC at the gate, you have a 12 V power supply which is fed from another location, and my money would be that you also have a comms cable in the same conduit, fed from a plug in transformer in the garage.

To complicate it even more, if you need a isolator, then you would have to fit one for the intercom, which could also be fed from a 230/12 transformer.

If it was a twin flex with 230V fed from the garage, as I have seen on many sites, then you have a problem, my only concern on your site, would be the volt drop.

[Tradie]

the reason low voltage lighting became such a big problem, which resulted in changes to the code, back in the day, was because people were installing 350 watt transformers, feeding 50 watt downlights with 0.5mm twin flex wire.

The regulations are created and adjusted according to challenges we encounter on a daily basis, just like all the generator regs, we identified challenges, back in 2007/8 when load shedding started, the technical people from the ECA were called in and so the regs were adjusted.

The question I am going to ask you, do you feel the the gate should have an isolator for the 12 V supply feeding the gate, because it is dangerous to work on the gate or could cause a fire, why would would you need an isolator and are you going to install an isolator for the intercom which clould also be 12V ?

[Tradie]

I see you mentioned 14.7V, this could be so high to make sure the voltage is at least 13 V at the gate for trickle charging the battery, is that at the transformer or at the gate, what is the volt drop at the gate ?

Does the motors run off the battery or the transformer? If it charges the battery.

To complicate things, are there lights at the gate, and do you have a power cable (230V) in the same conduit for the lights, that is what I would be concerned about.

[GCE]

To complicate it even more, if you need a isolator, then you would have to fit one for the intercom, which could also be fed from a 230/12 transformer.

Good point