Distribution Board Ways: 12, 18 or 24?

"Is 12 ways enough or should I take 18 or 24? Surface or flush?" Anyone fitting out a flat or shop asks this. In this guide from Tawredaat (توريدات), an electrical and finishing materials supplier in Cairo and Giza (see also our FAQ), we explain what is inside a board, a simple way to count the ways, surface vs flush and the most common mistakes. Numbers are sourced; anything without a public source is written as general guidance.

What is inside a distribution board?

A distribution board (consumer unit) is the box that splits the supply into the flat's circuits, each with its own breaker. IEC 61439-3 covers distribution boards operated by ordinary persons (household use), with outgoing devices per IEC 60898-1, IEC 61008, IEC 61009 or IEC 60269-3 (IECEE summary). Inside you usually find:

• ✔ Main switch/breaker: isolates the whole flat at once.
• ✔ Circuit breakers (MCBs): one per circuit, protecting against overload and short circuit. Breaker amps are covered in our apartment breaker guide.
• ✔ RCCB (residual current breaker): the title of IEC 61008-1 describes it as a residual current breaker without integral overcurrent protection, so it complements the MCBs and does not replace them. Schneider's guide says 30 mA high-sensitivity RCDs are used as additional protection, and that IEC 60364-4-41 requires them for general-use socket-outlets up to 32 A.
• ✔ Neutral and earth bars and wiring space.

How many ways do I need: 12, 18, 24 or 36?

The number of ways is the number of outgoing circuits the board can take (Electrical4Less). So the real question is how many circuits you have and will add. A simple method:

• ✔ 1) Count circuits: lighting (often more than one), sockets, one breaker per air conditioner, water heater, kitchen, washing machine and any heavy appliance.
• ✔ 2) Add spare ways: University of Missouri's design guideline asks for 20% spare capacity for future loads, and Electrical4Less says choosing a unit with spare capacity avoids replacing or extending the board later. 20% is an institutional example, not an Egyptian rule.
• ✔ 3) Pick the nearest available size from the table.
• ⚠ 4) Check the product sheet: manufacturers may count ways differently (the Hager 18 description says "18-module capacity"), so confirm whether the count includes the main switch and RCCB space.

Worked example (illustrative, not a fixed rule)

A flat with 2 lighting circuits, 2 socket circuits, 2 ACs (one each), a water heater, a kitchen and a washing machine has 9 circuits. Adding 20% gives about 11, so the nearest size is 12 ways. If you later add two ACs and a kitchen socket circuit you reach 12 circuits, about 14 with the margin, so 18 ways fits better.

The table figures are arithmetic from the example (circuits ÷ 1.2), not an official or Egyptian requirement. The final count is set by a qualified electrician or engineer after load and cable-route review.

Surface or flush?

The difference is how it is installed: a flush board sits in a recess inside the wall with only the front visible, so it must be planned before plastering and finishing. A surface board is fixed on the wall and protrudes, which suits finished walls where you do not want to break plaster. This is a general explanation; neither type is better.

Accuracy note: the 12-, 24- and 36-way boards and the standard Hager 18-way do not state surface or flush in their titles, so check the product page before buying and do not assume. For flush boards the incoming conduits must be planned too; see our conduit size guide.

Common mistakes when choosing and fitting a distribution board

• ⚠ No spare ways. The first new AC or heater forces you to replace the board or add another (Electrical4Less).
• ⚠ Too many circuits on one breaker. One breaker for the whole flat, or two ACs together, means any fault trips everything. Give each heavy appliance its own breaker; see our apartment breaker guide.
• ⚠ One RCCB for every circuit. Per Electrical4Less, with one shared RCD any fault disconnects all its circuits, while an RCBO per circuit isolates more precisely. Schneider notes selectivity is achieved by subdividing circuits or by time delay.
• ⚠ Mixing neutral and earth or wiring them wrongly. Each has its own bar and place; wrong connections can make the RCCB trip or stop protecting. This is a general principle; the wiring itself is for a qualified electrician.
• ⚠ Loose terminals. A loose connection heats up; tighten to the torque the manufacturer specifies.
• ⚠ Installing it yourself. Final design and wiring belong to a qualified electrician or engineer.

Distribution boards available on Tawredaat

Currently available (checked today):

• ✔ Beta 12-Way (BE.12M.VS.LN): 12 ways.
• ✔ Hager 18-Way Flush Mounted and Beta 18-Way Flush Mount (BE.18M.VS.LN): 18 ways, flush (per product title).
• ✔ Hager 18-Way Metal Distribution Board: 18 ways (mounting type not stated in the title).
• ✔ Hager 24-Way Metal Consumer Unit and Beta 24-Way (BE.24M.VS.LN): 24 ways.
• ✔ Hager 36-Way Metal Distribution Board: 36 ways.
• ✔ Sega M 6-Way (SRH06) Surface Mounted: 6 ways, surface, for a small sub-board.

See more in the electrical panels collection and circuit breakers and panels.

Frequently asked questions

Is a 12-way board enough for a flat?
It can be for a small flat if the circuit count plus a sensible spare margin fits in 12. Count the circuits first and have a qualified electrician or engineer confirm.

How many ways should I leave spare?
We found no fixed Egyptian figure. Some institutions design for 20% spare capacity (University of Missouri) as an example; the principle is to leave room for a new AC or heater.

Surface vs flush board?
Flush goes inside the wall and is planned before finishing; surface is fixed on the wall. Check the type on the product page.

Do I need an RCCB?
A 30 mA RCD is additional protection, and per Schneider IEC 60364-4-41 requires it for general-use socket-outlets up to 32 A. How it applies in your flat is for a qualified electrician or engineer.

Can one RCCB serve the whole flat?
It can, but any fault trips all its circuits. Splitting circuits over several RCCBs or using an RCBO per circuit isolates faults better (Electrical4Less, Schneider).

Can I install the board myself?
No. Design, wiring and final testing belong to a qualified electrician or engineer.

About Tawredaat: Tawredaat (توريدات) is an Egyptian supplier of electrical and finishing materials, serving homeowners, companies and contractors in Cairo and Giza. Questions? See our FAQ.

ملخص بالعربي: اعدّ دواير الشقة (إضاءة، بريز، قاطع لكل تكييف، سخان، مطبخ، غسالة) وزوّد أماكن فاضية للتوسعة (مؤسسات بتصمم بـ 20% احتياطي كمثال مش قاعدة مصرية)، واختار أقرب مقاس: 12 أو 18 أو 24 أو 36 خط. الغاطس جوه الحيطة قبل التشطيب والظاهر على سطح الحيطة. العدد النهائي لفني أو مهندس كهربا مؤهل. المتاح: لوحات Hager وBeta وSega M.