Powering a 5-bedroom duplex is one of the most demanding residential electrical jobs you will encounter in Nigeria. Done right, the installation will handle the load demands of a modern family, survive years of power voltage fluctuations, and comply with the Nigerian Electricity Regulatory Commission (NERC) standards. Done wrong, you are looking at nuisance tripping, damaged appliances, fire hazards, and a very unhappy client.
This guide breaks down every major electrical product category you need, from the incoming supply point to the final accessories, with sizing guidance, product types to specify, and Nigerian market context throughout.
Incoming Supply & Metering
The starting point of any residential installation is the incoming supply. For a 5-bedroom duplex, a single-phase 100A supply is the absolute minimum, but a 3-phase supply (3 x 63A or 3 x 80A) is strongly recommended. A 3-phase arrangement allows you to balance heavy loads, air conditioners, pumping machines, and inverter chargers across phases, reducing harmonic distortion and neutral current.
- Service entrance cable: Specify a minimum of 35mm² armored cable (SWA) from the DISCO pole or transformer to the meter position. In flood-prone areas or where the cable runs underground over long distances, use 50 mm² for headroom.
- Energy meter: Most DISCOs will install the prepaid meter, but as the contractor, you must prepare the meter box — a lockable GRP or galvanized steel enclosure mounted at 1.5m above finished floor level at the boundary wall. Ensure the meter box has adequate knockouts for the incoming SWA and outgoing tails.
Main Distribution Board (MDB)
The main distribution board serves as the nerve center of the installation when powering a 5-bedroom duplex. For this setup, specify either a surface-mounted or flush-mounted enclosure made from steel or GRP, with a minimum capacity of 24 ways. The busbar should be rated at no less than 125A to handle the load efficiently. If the property uses a 3-phase supply, ensure the busbar is configured as a 3-phase, 4-wire system to support balanced and reliable distribution.
Main Isolator / Incomer
Mount a 4-pole 100A MCCB (Molded Case Circuit Breaker) as the main isolator at the incomer position. This provides a means of isolating the entire installation for maintenance without the need to interfere with the DISCO supply. Specify a breaking capacity of at least 10kA; this is non-negotiable in a Nigerian grid environment where fault levels can be significant.
Surge Protection Device (SPD)
Install a Type 2 SPD (Class II) immediately after the main isolator. Nigerian grid supply is notorious for voltage transients, and an SPD protects all downstream equipment from impulse overvoltage. Specify a device with a discharge current (Imax) of at least 40kA per phase. Mount it in the incomer section of the MDB with short connecting leads.
RCDs (Residual Current Devices)
Nigerian electrical practice does not always enforce RCDs, but best practice and the IET Wiring Regulations (BS 7671), which forms the basis of most professional installations, requires RCD protection for socket outlet circuits and circuits serving bathrooms, outdoor areas, and kitchens. Install at a minimum a 63A/30mA RCD on each of these circuit groups within the MDB.
Circuit Breakers (MCBs & MCCBs)
Selecting the right circuit breaker type and rating for each circuit is where many contractors cut corners and where most electrical faults originate. Use the following guide for a 5-bedroom duplex.
MCB (Miniature Circuit Breaker) — final circuits
MCBs protect individual circuits within the distribution board. Always specify Type B or Type C MCBs depending on the load type:
- Type B MCBs (trip at 3–5x rated current): ideal for lighting circuits, socket outlets, and general-purpose circuits where no high inrush current is expected.
- Type C MCBs (trip at 5–10x rated current): specify for circuits feeding air conditioners, pumping machines, and motors where inrush current on startup would nuisance-trip a Type B.
Minimum MCB ratings for a 5-bedroom duplex:
| Circuit | MCB Type | Rating | Cable Size |
| Lighting (per floor) | Type B | 6A or 10A | 1.5mm² |
| General socket outlets | Type B | 20A | 2.5mm² |
| Kitchen sockets | Type C | 32A | 4mm² |
| Air conditioner (1.5HP) | Type C | 20A | 2.5mm² |
| Air conditioner (2.5HP) | Type C | 32A | 4mm² |
| Pumping machine | Type C | 20A | 2.5mm² |
| Electric shower (if specified) | Type C | 40A | 6mm² |
| Cooker/range | Type C | 32-45A | 6mm² |
MCCB (Moulded Case Circuit Breaker) — sub-mains & feeders
MCCBs are specified for the main incomer and for sub-main feeders between the MDB and any sub-distribution boards on upper floors. They offer adjustable trip settings and higher breaking capacities than MCBs. For a duplex, specify a 63A or 80A MCCB for the sub-main to each floor sub-board, depending on the calculated load.
4. Solar Inverter System
Reliable grid supply remains a major challenge across Nigeria, and most clients powering a 5-bedroom duplex will expect a solar inverter backup system as part of the installation. Understanding the electrical products involved ensures you can specify, install, and commission the system correctly.
Sizing the inverter
For a 5-bedroom duplex with essential loads (lighting, fans, TV, refrigerator, modest socket usage, and 2-3 air conditioners on backup), a 5kVA to 10kVA hybrid inverter is the typical range. The key specifications to check are:
- Continuous output power (VA and Watts) — ensure the inverter can handle simultaneous loads
- Surge capacity — must handle motor startup inrush, typically 2-3x continuous rating
- Battery type compatibility — specify a lithium (LiFePO4) compatible inverter if the client is investing in lithium batteries
- Solar input (MPPT rating) — check the maximum PV array voltage and current the MPPT controller can handle
- Grid/generator passthrough — essential for seamless changeover in a Nigerian installation
Switches, Sockets & Accessories
The finishing accessories are what the client sees every day, so quality and consistency matter. For a 5-bedroom duplex, specify one accessory range throughout and stick to it, mixing brands and finishes looks unprofessional and causes problems when replacements are needed.
Socket outlets
Specify Schneider switched socket outlets throughout. For kitchen and utility areas, use double-pole switched sockets with neon indicator. Specify shaver sockets in all en-suite bathrooms. For outdoor areas and the generator/plant room, use IP65-rated weatherproof socket outlets. A rough count for a 5-bedroom duplex:
| Area | Qty (Double Sockets) | Notes |
| Master bedroom | 4-6 | Include dedicated AC isolator switch |
| Other bedrooms (x4) | 3-4 each | Include AC isolator switch per room |
| Living/dining | 6-8 | Include TV and equipment points |
| Kitchen | 6-8 | Specify switched double-pole for high-power appliances |
| Study/home office | 4-6 | Consider USB charging sockets |
| Garage/utility | 4 | IP44 minimum; IP65 preferred |
| External | 2-4 | IP65 weatherproof mandatory |
Light switches
For a duplex, two-way switching is essential on staircases and in master bedrooms (to control the same light from two locations). Specify intermediate switches where three switching points are needed on the same circuit. Dimmer switches may be specified for living areas and the master bedroom to ensure the LED light fittings specified are compatible with the dimmer module selected.
Isolator switches
Each air conditioning unit must have a local isolator switch (double-pole, 20A or 32A as appropriate) mounted adjacent to the indoor unit for safe maintenance. The same applies to the water heater (if electric) and any built-in kitchen appliances. These are not optional — they are required for safe isolation in line with IET Wiring Regulations.
Quick Reference — Product Checklist
Use this as a pre-order checklist before starting a 5-bedroom duplex installation:
| Product Category | Key Specification | Priority |
| Service entrance cable | 35-50mm² SWA | Critical |
| Main distribution board | 24-way, 125A rated | Critical |
| Main incomer MCCB | 100A, 4-pole, 10kA | Critical |
| Surge protection device (SPD) | Type 2, 40kA per phase | Critical |
| RCDs | 63A/30mA, per circuit group | Critical |
| MCBs | Type B & C, see table | Critical |
| Solar inverter | 5-10kVA hybrid | High |
| Battery bank | 48V 200Ah LiFePO4 or tubular | High |
| Solar panels | 3.5-5kWp, mono-PERC | High |
| PVC conduit | 20mm, 25mm, 32mm | Critical |
| Wiring cables | PVC/PVC + SWA, certified | Critical |
| Socket outlets | 13A switched, IP65 for external | High |
| AC isolator switches | 20A or 32A DP per unit | Critical |
| Earth rods | Copper-bonded, 1.2m+ | Critical |
| Bonding conductors | 10mm² green/yellow | Critical |
Conclusion
Powering a 5-bedroom duplex is not a small undertaking, but getting the product selection right at the planning stage saves time, money, and reputation on site. This guide covers the core electrical products every contractor should be comfortable specifying and sourcing.
Flux Energy stocks the full range of products covered in this guide – genuine Schneider distribution boards, MCBs, MCCBs, SPDs, RCDs, solar inverters, switches, and sockets.
Call or text 0802 240 0634 or visit www.fluxenergy.ng
