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Cable Length in Meters

Circuit Type

DC Amps

10% Voltage Drop (Non-Critical)

3% Voltage Drop (Critical)

















0-6 m

0-2 m

6-9 m

2-3 m

9-15 m

3-4.5 m

15-19 m

4.5-6 m

19-24 m

6-7.5 m

24-30 m

7.5-9 m

30-40 m

9-12 m

40-51 m

12-15 m

51-61 m

15-18 m

18-21 m

21-24 m

24-27 m

27-30 m

30-33 m

33-37 m

37-40 m

The above cable sizing table is used by running across the top row until the column with the relevant amperage is found, and then moving down the left-hand column until the row with the relevant distance is reached. The colour coding in the body of the table at the intersection of this row and column is the wire size. Compare this with the Cable Conversion Table to see what size cable to use.Wire sizes are denoted by colour coding. 


A common way for referencing a cable size is its “gauge.” The AWG ( American Wire Gauge (AWG) is used as a standard method of denoting wire diameter, measuring the diameter of the conductor (- measured as only the bare wire ) with the insulation removed. AWG is sometimes also known as Brown and Sharpe (B&S) Wire Gauge.

Also listed Below is a conversion chart from AWG/B&S to mm². This table gives the closest equivalent size cross references between metric and American wire sizes. In Europe and Australia, wire sizes are expressed in cross sectional area in mm².

















Diameter (mm)














Cross Section (mm2mm2)














Colour Code


While is possible to use the same cables , (as far the diameter will be the appropriate one) for AC and DC circuits, it is advisable to use different coloured cables between the two types of currents, both to increase handling safety but also to make installation and repair work much faster. In If existing appliances or installations have colours, logistics managers may consider replacing or standardising them by re-colour coding the wires with an external paint or marking in a method that makes sense.

A general colour cod for AC looks like:

  • Neutral: blue Blue.
  • Phase: brown Brown or black.
  • Ground: green Green/yellow.

The neutral and the phase are the two connections for the electricity, the ground is for safety.


+ = red or blue
- = black or brown

However, many Many differing international standards apply however. Please reference the below table for colour coding of different countries and regions around the world 

Standard Wire Colours for Flexible Cable

(e.g. Extension Cords, power cords and lamp cords)

Region or Country



Protective Earth/Ground

European Union (EU), Argentina, Australia, South Africa

Australia, New Zealand




United States, Canada




(green) or


Standard Wire Colours for Fixed Cables

(e.g. In/On/Behind the wall wiring cables)

Region or Country



Protective Earth/Ground



European Union and UK


UK Prior to March 2004


Australia, New Zealand

Any colours other than:


Recommended for single-phase:


Recommended for multi-phase:


 (since 1980)

 (since 1980)

bare conductor, sleeved at terminations (formerly)


South Africa


bare conductor, sleeved at terminations

India, Pakistan

United States


(120/208/240V) (brass),






bare conductor

(ground or isolated ground)




(single-phase isolated systems)


(three phase isolated systems)




bare conductor

(isolated ground)

Important points to bear in mind note when wiring. :

  • All circuits should be removed from the floor and be as be high as possible with no connections in or near water or damp areas.
  • All cable lug connections should be securely crimped to the wire termination with a band, and not soldered in place.
  • Tinned cable – copper wire that has been coated with a thin layer of tin to prevent corrosion - It is preferable to use where possible in a marine environment or near salt water.
  • Never tap into or splice existing circuits when installing new equipment; run a properly sized new duplex cable (positive and negative cable in a common sheath) from the distribution panel (or a source of power) to the appliance.
  • It is recommended to label all cables at both ends, and to an updated wiring plan to aid in future troubleshooting. Copies of the wiring plans can be even be stored in locations such as the fuse box or distribution box so that future users can reference them.
  • Each circuit should have an independent ground cable, and all the ground cables should eventually be tied back to a common ground point/bus bar which is grounded to the battery negative; if devastating stray current is to be avoided, this is the only point at which the grounds should be interconnectedbusbar.
  • Unless in a conduit, cables should be physically supported at least every 450mm.
  • Although black is often used for DC negative, it is also used for the live wire in AC circuits in the USA. That means there is potential for dangerous confusion. DC and AC wiring should be kept separate; if they have to be run in the same bundle, one or the other should be in a sheath to maintain separation and ensure safety.


Protective devices for electrical circuits ensure that under fault conditions a high current cannot flow under faulty conditions, protecting the installation and equipment , and preventing injury and harm to persons nearby handling or handling the circuit or in the near vicinity of equipment. Protection Overcurrent protection is assured through physically detaching the power supply in a circuit through overcurrent protection, which removes fire hazards and risk of electrocution.

Protective devices might include:

  • Fuses.
  • Miniature Circuit Breakers (MCBs).
  • Residual Current Devices (RCDs).
  • Residual Current Breakers with Overcurrent (RCBOs).

All of the aforementioned devices protect users and equipment from fault faulty conditions in an electrical circuit by isolating the electrical supply. Fuses and MCBs only isolate the live feed; with while RCDs and RCBOs isolate both the live and neutral feeds. It is essential that the appropriate circuit protection is installed to ensure an electrical installation is safe.


A fuse is a very basic protection device used to protect the circuit from overcurrent. It consists of a metal strip that liquefies when the flow of current through it surpasses a pre-defined limit. Fuses are essential electrical devices, and there are different types of fuses available in the market today based on specific voltage and current ratings, application, response time, and breaking capacity.

The characteristics of fuses like time and current are selected to give sufficient protection without unnecessary disruption.

Miniature Circuit Breaker (MCB)

An MCB is a modern alternative to fuses, and are maybe usually centrally located in buildings – usually called a “fuse box” or “breaker box”, or attached to specific equipment. They are just like switches, turning off when an overload is detected in the circuit. The basic function of a circuit breaker is to stop the flow of current once a fault has occurred. The advantage of MCBs over fuses is that if they trip, they can be reset without having to replace the whole MCB. MCBs can also be calibrated more precisely than fuses, tripping at exact loads. Circuit breakers are available in different sizes from small devices to large switch gears which are used to protect low current circuits as well as high voltage circuits.

Residual Current Device (RCD)

Residual Current Devices (or RCDs) are designed to detect and disconnect supply in the event of a small current imbalance between the Live live and Neutral neutral wires at a pre-defined value - typically 30mA. RCDs can detect when a live conductor touches an earthed equipment case, or when a live conductor is cut through; this type of fault is potentially dangerous and can result in electric shocks and fires.

An RCD does not give safety against a short circuit or overload in the circuit. It cannot detect – for example - a human being accidentally touching both conductors at the same time. An RCD cannot replace a fuse in function.

RCDs can be wired to protect a single or a number of multiple circuits - the advantage of protecting individual circuits is that if one circuit trips, it will not shut down the whole building or distribution system, just the protected circuit.

Residual Current Breaker with Overcurrent (RCBO)

An RCBO combines the functions of a MCB and an RCD in one unit. CRBOs are a safety device which detects a problem in the power supply and is capable of shutting off in 10-15 milliseconds.

They are used to protect a particular circuit, instead of having a single RCD for the whole building.

These devices are testable as well as resettable apparatusare able to be reset. A test button securely forms a tiny leakage condition; along with a reset button again connects the conductors after an error state has been cleared.


Uncontrolled electricity can injure or even kill humans or animals. One A common and effective way to control electricity is through grounding. Grounding is a physical connection to the earth that draws electric charge safely to the ground allowing a large space for electrons to dissipate away from humans or equipment. A grounding system is gives excess positive charge in electrical lines an attractive place to go – the access to a negatively charged ground wire – wires, eliminating the dangers of fire and electrocution.


The term "ground" refers to a conductive body, usually the earth. "Grounding" a tool or electrical system means intentionally creating a low-resistance path to the earth’s surface. When properly done, current from a circuit follows this path , thus preventing the buildup build-up of voltages voltage that would otherwise result in electrical shock, injury and even death. Grounding is used to dissipate the damaging effects of an electrical short, but also used to prevent damage from lightening as well.