Home Engineering Tools Panel Space & Fill Calculator

Panel Space & Fill Calculators

Sizing tools for panel builders and switchboard assembly engineers: DIN rail module count (TH35), metric cable gland selection, cable tray fill capacity, and copper busbar ampacity.

IEC 60715, IEC 62444 & IEC 61439 Free, no sign-up Practical Switchboard Sizing
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Dimensions & Load
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Sizing Result
Select What You Need to Size

Choose one of four panel assembly calculators.

Enter Dimensions & Quantities

Fill in the physical sizes or ratings for your installation.

Assembly & Installation Conditions

Specific physical options impacting the final arrangement.

Calculation Result & Specification

Below is your detailed sizing result, recommended components, and standards verification.

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Indicative result — verify before you buy

This calculator provides technical guidance for switchboard layout, gland selection, and tray fill. Final panel design must comply with manufacturer temperature-rise limits (IEC 61439) and short-circuit withstand requirements. Mega Standard accepts no liability for decisions made on these figures alone.

Standards & method
IEC 60715 Dimensions of low-voltage switchgear and controlgear — Standardized mounting on rails (TH35 top hat rail).
IEC 62444 / EN 50262 Cable glands for electrical installations — Metric thread specifications M12 to M63.
IEC 61439-1 Low-voltage switchgear and controlgear assemblies — Busbar current-carrying capacity and temperature rise limits.

Calculations assume standard industrial TH35/7.5 DIN rail, brass or polyamide metric glands, and E-Cu copper busbars at 30 K temperature rise.

How Panel Builders Size DIN Rails, Glands, and Trays

Switchboard layout requires balancing physical component space, thermal dissipation, and cable bend radiuses. Under-sizing cable trays or busbars causes thermal hotspots and short-circuit failures.

DIN Rail Module Standard (1 TE = 18 mm)

IEC 60715 defines the standard 35 mm top-hat rail (TH35). Electrical components (MCBs, RCCBs, timers) are measured in TE (Teilungsheinheit) or module widths, where 1 TE = 18 mm.

Metric Cable Gland Selection Chart

Standard M-thread clamping ranges per IEC 62444:

M12 × 1.5  ──►  Cable OD  3.0 –  6.5 mm
M16 × 1.5  ──►  Cable OD  4.0 –  8.0 mm
M20 × 1.5  ──►  Cable OD  6.0 – 12.0 mm
M25 × 1.5  ──►  Cable OD 10.0 – 14.0 mm
M32 × 1.5  ──►  Cable OD 13.0 – 18.0 mm
M40 × 1.5  ──►  Cable OD 18.0 – 25.0 mm
M50 × 1.5  ──►  Cable OD 25.0 – 32.0 mm
M63 × 1.5  ──►  Cable OD 34.0 – 44.0 mm

Always verify whether armored cable (SWA) requires a two-part BW/CW gland for earth continuity of the steel wire armor.

Common Panel Assembly Errors

  • Filling cable trays beyond 40%. Overcrowded trays prevent air circulation, causing cables to overheat and trip breakers prematurely.
  • Ignoring end-stop clearance on DIN rails. Terminal blocks require end stops and end covers; failing to account for them leaves insufficient rail length.
  • Sizing copper busbars without derating for ambient heat. In an Iraqi summer (50 °C ambient), busbars must be derated to maintain safe operating temperatures.

Frequently Asked Questions

What is 1 TE or 1 Module on a DIN rail?

1 TE (Teilungsheinheit) or 1 Module equals exactly 18 mm in width. A standard 1-pole MCB is 1 TE wide, a 3-pole MCB is 3 TE (54 mm), and a 4-pole RCCB is 4 TE (72 mm).

What is the maximum cable tray fill limit?

Under IEC 60364 and NEC 392, the maximum recommended fill for power cables is 40% of the tray cross-sectional area, and 50% for control/signal cables.

Which gland IP rating is needed for outdoor panels?

Use IP66 or IP68 metric brass glands with neoprene O-rings to match outdoor IP65/IP66 enclosure ratings.

Does Mega Standard supply terminal blocks and glands in Iraq?

Yes! We stock Phoenix Contact, Legrand, and Schneider terminal blocks, cable glands, wiring duct, and copper busbar supports in Kirkuk.

Need Legrand, Schneider or Phoenix Contact panel accessories?

We supply genuine terminal blocks, DIN rails, metric cable glands, wiring duct, and busbar supports across Iraq from our Kirkuk inventory.

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In Stock in KirkukPhoenix Contact, Legrand & Schneider terminal blocks ready to ship.
Technical SupportComplete panel assembly support for panel builders across Iraq.
Supported locallyKirkuk-based since 2012, with spare parts and service across Iraq.
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