hi guys.. just wanted to ask some expert here.. what is the maximum amp that a 4mm cable with radial looping can take ? I read somewhere that a 2.5mm cable can take 20amp for radial circuit and 30amp for ring circuit... hope to get some help from some sifus here..

This is not actually straight answer. Ability of wire to transfer current is different when transmitting over free air, inside concrete wall, how close two wire together, in trunking, etc. It also depends in ambient temperature.

In general, it is about 20A for 2.5mm cable. The ring circuit can carry more just because the current can be supplied in both direction from the Main Distributor Box. You can refer from this for Malaysia Guideline from Suruhanjaya Tenaga (ST)

http://www.st.gov.my/index.php/en/download...ntial-buildings

The 4mm can carry 26A under 30C ambient temperature. I'm no sifu

I'm no sifus but was also interested to know... My understanding is that the length of cable also play a part. By the way, what you want to use it to power for? Home appliance rarely take more than 20A

copper or aluminium ?
made in malaysia or PRC ?
mega kabel or other brands ?
in the wall or outside ?

better put a decent margin

Refer to the link I provided. I think it is easy to understand. Very good guide by ST

NICE

thanks a lot guys its actually conceal in concrete wall with pvc conduit....not using mega cable but made in malaysia cable with SIRIM

with JKR and ST chop is better quality

Conceal cables will carry less load. 2.5mm in paper specification can go more than 20amps, but in real life use is better to be limit to 15amps. We cannot guarantee copper purity, bending issues that reduce the copper conductivity etc..

Here can give you some rought guide, always go lower than recommendation, don't go test threshold when life is at stake.

http://www.cable-ratings.co.uk/

I would go with the Suruhanjaya Tenaga guidelines and progressively updated..

Hi, i would like to ask is it safe for live wire for light and ceiling fan to be running at the floor?
And also is it safe for 2x1.5mm and 1x 1.5mm cable to supply 2 rooms and 1 bathroom, with heater, total of 7 sockets and 5lamps, 1 exhaust fan?

I assume you are running it on first floor for ground floor light if that is ok? You have to know where the wires are if not in future it you drill the floor will hit the wires. putting under the ground floor will be bad as moisture and underground termites may damage the cables.


1.5mm are way too thin, you need minimal 2.5mm, and each room minimal need one mcb, bath room seperate mcb.

It's in the ground floor living room, the wiring supplies fan and light, have 5 wires running in the ground but exposed like this..



This post has been edited by tangenttheta: Apr 28 2017, 11:08 AM


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This is really a lousy wiring man job. Furthermore without conduit. Good luck.

All standard wiring have to come from top to bottom, not bottom up, water is bottom up.

Unless you have steel wall

I see.. so this is not the standard doing ya? Thanks thanks man..

where do u get to hear about ring and radial circuit?
Are you asking for your house renovation work? or Office, etc.?

House... wanted to loop further points... hence wanted to know the limitations...

keep in mind the standards are referring to genuine copper cable.
many fakes out there ya

Ring circuit and looping are two different things.

usually people do radial only.
Ring is more to office.. Where there is redundancy if wiring been cut off. U can imagine?
Just wondering where u heard all these term.

Yeah i am aware that house all using radial circuit... im just stating what i read from some guidelines that if you have ring circuit your cable can take more amps... though not much people using ring.. even in offices =D

The primary reason for using a ring circuit is to support more switch socket outlets over a wider area on a single breaker..

A ring circuit covers 100m2, using 2.5mm2 PVC copper conductor on a single 30 or 32A circuit breaker..

If covering a smaller area just run radial circuit,

- 2.5mm2 for 20m2 on a 20A circuit breaker or

- 4mm2 for 50m2 with a 32A breaker..

I have not really come across people talking about ring circuit so there will be cost saving when this ring circuit is able to loop up more power point. (Maybe i have not seen that much)
We usually talk about ring circuit is the redundancy when some wiring somehow breaks and the power point still can work, as the way they are wired is different.

can refer to page 17 in pdf below
Guidelines For Electrical Wiring In Residential - Suruhanjaya Tenaga
(search and download from google)

Not exactly sure what is your application / reason to do so (just want to save money as looping is cheaper? My thinking is costing can be subjective from contractor to contractor anyway. ). But u just have to understand wiring is designed to carry certain Amps, while MCB (circuit breaker) to ensure Amps flowing thru it will not exceed certain Amps.
Wiring can be oversized but MCB rating shall never be bigger than wiring.
Wiring burnt when carrying higher Amps than it is specified and MCB will not trip if it is not selected properly.

And if you compare the schematic from ST, radial circuit vs ring circuit.. isnt that ring circuit will just an additional looping / return wiring to the MCB.. so shouldnt it be costing more?
Well, up to ur contractor to advise.

This post has been edited by heyamazingpeople: May 5 2017, 12:27 AM

The "Malaysian" wireman will define looping as radial.

While actual looping technically can handle more load because the current are return back to mcb via 2 path. Ring will give redundant and more current. But will also give the danger of over load the wires if one of the path break and load are running high.

Hi Guys,

Can anyone explain to me whether my understanding is correct or not? For no 1-3, is that correct?

And what is no 4? it looks like RCD as well but i do not understand why there are so many RCD in this setup.

Thanks a bunch.

No 3 come from no 4 in the left am i right?

#4 Delixi CDB6VR is a electromagnetic RCCB.

Do note that "RCD" is a very broad term. Many different types of Residual Current Devices (RCD) exist.

For comparison sake:

RCCB. (Residual Current Operated Circuit Breaker without Integral Overcurrent Protection)
RCBO. (Residual Current Operated Circuit Breaker with Integral Overcurrent Protection)


RCCB is only an earth leakage protection device.
RCBO is Short circuit current protection device as well as earth leakage protection device.


The RCCB only measures the out of balance in current in the active and neutral wires. This is the current leaking to ground. It protects you against shock.
The RCBO does what the RCCB does, plus it has overload protection.