Electrical cable advice

[shaneo]

Hi it's Shaneo here, I'm an electrical contractor on the South Coast and would appreciate some advice on what size electrical cable to use from the Eskom box to a single phase 63A DB board for a domestic installation (4 bedroom house). The distance from the box to the house is 160m and the cable will be buried. I've been looking at the voltage drop tables but not 100% sure if I'm understanding it correctly. Not sure whether to go with 16mm ECC or 25mm ECC, Thanks.

[GCE]

Hi

I am assuming that the Eskom CB is 63 Amp feeding the installation and that it is not a 80 Amp supply feeding a 63 Amp isolator in the DB.

I have found that it is best to use SANS 10142 tables to determine the cable distances vs Amps needed especially on single phase .I have attached the page for reference.

I would go with 25 sqmm

[shaneo]

Great thank you for the advice GCE, I think I will go with the 25 sqmm.

[shaneo]

Hi

I am assuming that the Eskom CB is 63 Amp feeding the installation and that it is not a 80 Amp supply feeding a 63 Amp isolator in the DB.

I have found that it is best to use SANS 10142 tables to determine the cable distances vs Amps needed especially on single phase .I have attached the page for reference.

I would go with 25 sqmm

Thank you for your advice GCE, I think I will go with the 25 sqmm cable.

I have another quoestion related to the same property.....
As I mentioned, the Eskom box is 160m from the house, but only 10m from the gate and I need to get power to the gate for the electric gate motor. Can I run 2 cables from the Eskom box, one up to the house (160m) to feed the house DB board and one to a weather-proof DB at the gate (10m)? Or do I have to run another 160m of cable back to the gate from the house DB board?
If I can run a 10m straight from the Eskom box to the gate DB, how would I label the DB's, are they both labelled as main DB's fed from the Eskom box?

[ians]

Thank you for your advice GCE, I think I will go with the 25 sqmm cable.

I have another quoestion related to the same property.....
As I mentioned, the Eskom box is 160m from the house, but only 10m from the gate and I need to get power to the gate for the electric gate motor. Can I run 2 cables from the Eskom box, one up to the house (160m) to feed the house DB board and one to a weather-proof DB at the gate (10m)? Or do I have to run another 160m of cable back to the gate from the house DB board?
If I can run a 10m straight from the Eskom box to the gate DB, how would I label the DB's, are they both labelled as main DB's fed from the Eskom box?

Not sure about Eskom ...but i dont believe you can fit additional breakers in the meter box...Run the main cable from the eskom meter box to a weather proof "main DB" inside the property at the gate...fit a breaker for the house and others as required ...earth leakage if you plan to fit a plug etc...then run the cable from the "main DB" to a "Sub DB" inside the house...just a note it might pay you to fit a galv steel steel pipe for the cable... pour a bit of concrete over the steel pipe after installing it and compact the ground as best you can...other wise there is a good chance the cable will be removed shortly after you install it...or make sure the power is ready when you install the first section to the gate...then once the main DB is installed and you can power...dig and lay the rest of the cable...unless of course you live in a secure neighborhood.


down the road from my house ...the guys installed about about 500 metres of cable half a metre deep and compacted the ground ...next morning...half the cable had been removed and the balance the following night ..they hooked it to a vehicle and pulled it out the ground.

[GCE]

I would take a cable from the Eskom kiosk to my own kiosk and label it as main D/Board.
From the main DB I could then run a circuit to the gate motor and a 2nd circuit to , what would now be , a Sub DB in the dwelling.

You would need to look at the cost of the kiosk, isolator and 2 CB's vs running surfix to the gate motor from inside the dwelling.

Even at 160m the cost may be close to each other and then take in the risk of damage/ theft of the kiosk.

[Derlyn]

Where is the meter ? Prepaid in the house or credit meter in Eskom Stubby. If there is a prepaid meter in the house then you will have to run a cable from the house for metering purposes. Doubt very much whether Eskom or your Local Municipal Supplier will give permission to feed the gate from the stubby.

Cheapest way to wire the gate motor from the house is to make sure the motor unit has a low voltage control board. That way, you could use 0.75mm twin flex in conduit underground for the gate supply from a plugin 18V transformer. As long as there are no lights involved at the gate.

Derek

[ians]

Where is the meter ? Prepaid in the house or credit meter in Eskom Stubby. If there is a prepaid meter in the house then you will have to run a cable from the house for metering purposes. Doubt very much whether Eskom or your Local Municipal Supplier will give permission to feed the gate from the stubby.

Cheapest way to wire the gate motor from the house is to make sure the motor unit has a low voltage control board. That way, you could use 0.75mm twin flex in conduit underground for the gate supply from a plugin 18V transformer. As long as there are no lights involved at the gate.

Derek

150 m of 0.75mm twin flex in a conduit fed from an 18 volt transfomer? eeeeish...i do realise... generally the gate is driven by the battery and not the supply (only use to charge the battery) but that is a long run for 18 v.

Something else to consider...i would "assume" (and not knowing what the customer requires) that there is a good chance a light could be fitted on the gate posts (LEDs...small power)...the fence could get electrified...security lights or just general light near the gate...CCTV for security near or close to the gate...so a power supply to a nano and switch to wireless link to house...and with homes going the smart route ...you could open and close the gate...switch on the lights etc etc etc.

As GCE mentioned a floor mounted kiosk on the inside or weather proof DB built into the wall on the inside would be the best route.

A few things i have learnt about fibre glass weather boxes and DB's ...always paint them other wise they look terrible after a few years and the clear glass door cracks and look like crap...fit a dark tint on the clear section...otherwise they crack...i wouldn't recommend a steel or even S/S because being close to the beach.

[Derlyn]

As I said, as long as there are no lights involved at the gate.

I always recommend low voltage for gates. The furthest I've done was 130 meters and the voltage at the gate was 15,8 V ( enough for charging the battery )
Another advantage is that no weatherproof isolator at the gate motor is needed, whereas with 240 Volt it is a requirement.

There are many variables, but the main question is .... where is the meter going to be located ? In the house or in the Eskom stubby ?

If the meter is in the house then the main DB will have to be in the house with a cable from the house to the gate motor.

If the meter is going to be in the house, then a kiosk close to the gate is not an option.

Derek

[shaneo]

Thanks to everyone for the advice, will be running a 25 sqmm up to the house and then a surfix back down to the gate as lighting will be required at the gate, and because of gate location, theft or damage to a kiosk or DB is a possibility. Does a 4 sqmm sufix supplied from a 5A circuit breaker sound right? And can I run them in the same trench?

[ians]

Thanks to everyone for the advice, will be running a 25 sqmm up to the house and then a surfix back down to the gate as lighting will be required at the gate, and because of gate location, theft or damage to a kiosk or DB is a possibility. Does a 4 sqmm sufix supplied from a 5A circuit breaker sound right? And can I run them in the same trench?

It sounds ok ...however i would still check the tables and make sure...running the 2 in the same trench shouldnt be a problem so long as you dig the trench deep enough for the surfix unless you use mechanical protection...a 25 mm ecc cable already has mechanical protection.

just a note with regards to theft ...mounting cameras visible to the criminals and mountin them high up on the side of a building is not smartest thing to do...if you have a crime issue...use facial recognition cameras which are hidden low enough that they can see the face and not cover by a hood or cap...the new systems will alert you if a person is trying to hide their face and send you a notification...cctv is becoming a more reliable form of crime detection...back in the day when 480 line cameras where used ...they were more for movement than anything else...new technology has made them a much better crime prevention tool if installed and setup correctly in the right locations.

something else while of the crime subject...cctv ...wireless nano units etc etc ...for neighborhood watch is becoming a very useful tool...if you are smart you will have a fibre cable installed to a point get the max speed available and not suckered by companies trying to screw you with FUP clauses...then fit cameras around the hood...with wireless nano stations which will serve 2 purposes.

one give all the patrollers access to free wifi making it easy to link to cameras setup around the hood to view if required which would mean you can stream in HD...and saving you tons of cash having to pay to transmit via cellphone networks...you dont need to send the data to a XVR and them try download later blah blah...something to think about...just make sure the network is secure.

[Tang]

Hi guys.
I'm under the impression that no other cable is allowed in the same trench as main supply to house. I do not have the book to confirm but I'm sure I read it somewhere.

[GCE]

Hi Tang

No other cable is allowed to run in the suppliers trench.
In this case you will be running the cables in a trench after the point of supply and so it will not be the suppliers cable or trench.

6.4 Positioning and fixing of cables
6.4.1 Positioning
A cable shall not be run
a) in the same trench or wireway as a supplier's cable, except with the
supplier's permission,

[Tang]

Ring circuits for elv

Hi guys.
Are there anything restricting me making a ring circuit on a 12m long
24V led tapelight?
Would appreciate your input.

[GCE]

I would get the suppliers consent in writing to prevent a come back. Trust me the comeback happens fast with some of the LED tape.Make sure it is mounted onto alu strips as a heatshink
Majority do not want you to use tails longer than 5m , so I would think you may have a problem.


I am on a contract at the moment and have left the consultant and preferred supplier to fight out the tail length - They have got to 10m , whereas the design calls for 30m on the longest run