Electrical Calculator — No. 07
Cable Size
Calculator
Load power aur cable length daalo — IEC 60364 ke hisaab se recommended cable size. Copper aur Aluminium dono. Voltage drop bhi.
Calculator
Phase Type
Motor ya load ki rated power
Valid power > 0 chahiye
Valid voltage chahiye
0.80-0.95 typical
0.1 to 1.0 chahiye
Source se load tak – one-way
Valid length > 0 chahiye
Gulf mein 35-40C common – derating zaroori
Result — Recommended Size
—mm2
Design Current
—A
Full load Ib
Cable Ampacity
—A
Derated Iz
Voltage Drop
—%
IEC max 5%
Next Size Up
—
Future load
ke liye
ke liye
Theory + Site Knowledge
Cable Size Kaise Choose Karte Hain?
Bhai, Gulf ki har site pe yeh sawaal aata hai. Qatar University, Sidra Hospital, Al Daayen — har jagah cable selection mera daily kaam tha. Ek galat size — ya toh overheating, ya voltage drop, ya MCB trip. Teeno costly hain.
Cable size choose karte waqt 4 cheezein dekho: design current (Ib), installation derating (Cf), temperature derating (Ct), aur voltage drop check.
IEC 60364 Method
3-Phase: Ib = P / (1.732 x V x PF)
1-Phase: Ib = P / (V x PF)
Iz_required = Ib / (Cf x Ct)
Table se select: Iz >= Iz_required
Voltage Drop <= 5%
1-Phase: Ib = P / (V x PF)
Iz_required = Ib / (Cf x Ct)
Table se select: Iz >= Iz_required
Voltage Drop <= 5%
Derating — Gulf Mein Critical
| Condition | Factor | Effect |
|---|---|---|
| 30C standard | 1.00 | No derating |
| 35C Gulf indoor | 0.94 | 6% loss |
| 40C Gulf outdoor | 0.87 | 13% loss |
| Cable tray open | 1.00 | Best |
| In conduit | 0.80 | 20% loss |
| Bunched cables | 0.70 | 30% loss |
Sidra Hospital — Real Example
Load: 15kW, 415V 3-ph, PF 0.85, 60m, conduit, 40C
Ib = 24.5A → DR=0.696 → Iz_req=35.2A → 10mm2 Cu selected
50m+ run hai to voltage drop zaroor check karo. Voltage Drop Calculator
Frequently Asked Questions
MCB rating cable ki ampacity (Iz after derating) se zyada nahi honi chahiye. Rule: MCB <= Iz.
IEC tables 30C pe hain. Gulf mein 40-50C ho jaata hai. Cable capacity kam hoti hai — derating ignore karo to fire risk.
Conduit mein heat trapped hoti hai — cable freely dissipate nahi kar paati. Open cable tray best hai.
Future load growth margin aur lambi runs mein voltage drop comfort ke liye next size up safe rehta hai.
VoltGuru.in — Electrical Knowledge for Gulf Professionals / IEC 60364-5-52