CablesEIT 2001-56 · Chapter 5

Cable Sizing Calculator

Copper PVC / XLPE cables per the Thai Electrical Code EIT 2001-56 (วสท. 2556), installation groups 1–7: conduit, clipped direct, insulators, buried and cable tray.

Load & Cable

Design current and cable construction

Load

System

Design current Ib— (A)

Cable

Insulation

Cores

Installation

Method, ambient temperature and grouping (EIT Table 5-47)

Method

Installation group

Ambient air temperature— (°C)

Grouping

Circuits in same conduit

Table 5-8

Voltage Drop Check

Upsize automatically when the drop exceeds the limit

Check voltage drop for this run

Voltage— (V)

Line-line

Length— (m)

Power factor

Limit— (%)

EIT 3.6: 5 % total

Calculation Results

Cable size

mm²

Cu PVC

Corrected Iz

117.0

Loading Ib / Iz

Voltage drop

0.94

Governed by current-carrying capacity.

EIT 3.6 limits the total drop from the meter to the last outlet to 5 %; this check covers this run only.

Size the breaker for this cable →

Calculation BreakdownFactors, formula and table lookups

Ambient factor Ca: 1.00
Grouping factor Cg: 1.00
Required It = Ib / (Ca·Cg): 100.0 A
Tabulated It, Table 5-20: 117 A
Corrected Iz = It·Ca·Cg: 117.0 A
Size by ampacity alone: 50 mm²
Conductor resistance: 0.4630 Ω/km @ 70 °C
Voltage drop: 3.77 V

Code Reference

Standards this calculation is based on

EIT 2001-562556
Ampacity Table 5-20
EIT 2001-562556
Ambient Table 5-43; grouping Table 5-8
IEC 60364-5-52
Annex G voltage drop; IEC 60228 resistance

Always verify against the standard edition and utility requirements that apply to your project before issuing for construction.