Congo-Brazzaville CBD High-Rise Office Building, Republic of the Congo

In early 2023, we received an inquiry from China Construction Group Central & West Africa Company. They were building a 35-story CBD office tower in Brazzaville, capital of the Republic of the Congo, with 45,000 square meters total floor area and 8,500kVA installed capacity. The project electrical consultant, French firm Egis Group, required full IEC certification for all cables. The client had approached multiple suppliers in Europe and Africa, but none could offer complete certification, acceptable delivery schedules, and full product range from small wiring to high-voltage power cables.
The client's pain point was clear: they needed a single supplier who could handle all cable requirements, hold complete IEC certification, and deliver within six months. They had been burned on a previous West African hotel project where cable delivery delays pushed mechanical and electrical installation back three months, resulting in heavy penalties. This time, they were taking no chances.
Site Investigation and Key Findings
At the end of February, our engineer flew to Brazzaville for site investigation. Three critical issues emerged that directly affected cable selection.
First, the riser space constraint. The core wall electrical riser measured only 1.2 meters by 0.8 meters clear, yet had to accommodate electrical, data, fire protection and other services. The original design using armored cables simply wouldn't fit—the bending radius was too large and the space too tight. We recommended switching to non-armored YJV cable for levels six and above, using 4×240mm² and 4×300mm² specifications. The smaller bending radius and lighter weight allowed optimized routing, while armored types were retained for basement and podium levels where mechanical protection was essential. This adjustment passed design review without issue.
Second, oil resistance in the basement. Level B3 housed diesel storage tanks and generator rooms where standard PVC sheathed cables would degrade within two years. We upgraded the H05VV-F flexible cables in this zone to oil-resistant grade, particularly the 3×16mm² large-section specification used for generator to emergency distribution connections, ensuring long-term stability in oily environments.
Third, climate adaptation. Brazzaville sees 40°C temperatures in dry season and 85% humidity in wet season. We modified the YJV insulation compound to water-tree-resistant XLPE and specified cold-shrink silicone rubber outdoor terminations instead of heat-shrink types, preventing cracking under extreme heat.
Supply and Execution
The supply contract was signed on March 12, 2023, for approximately USD 1.27 million, with delivery in four batches timed to construction progress.
First batch arrived in April, covering urgent distribution board installation needs: H07V-U rigid single-core and H05V-K control cables from 1.5mm² to 25mm², totaling over 200,000 meters. The basement structure had just completed, perfect timing for electrical room construction.
Second batch arrived in May, focusing on H05VV-F flexible cables including 2,400 meters of 3×16mm² large-section specification for floor distribution connections. This cable uses 126 strands of fine copper wire, 18.5mm outer diameter, bending easily in tight distribution board spaces. The installation team reported it pulled through more smoothly than other brands they had used. This batch arrived as levels 1-10 structural work completed, matching the fit-out schedule.
Third batch arrived in July, the riser backbone YJV cables: 3,600 meters of 4×240mm² for levels 6-20, and 2,800 meters of 4×300mm² for levels 21-30 and high-load floors. The riser shafts had just been capped, ready for vertical installation.
Fourth batch arrived in September, the heaviest SWA steel wire armored cables: 850 meters of 4×400mm² for municipal main incoming lines, and 620 meters of 4×500mm² for diesel generator emergency circuits. Single drum weights approached nine tonnes. We booked heavy lift equipment at Pointe-Noire port two weeks in advance to ensure smooth unloading. The main transformers and generators were positioned and ready for termination and commissioning.
Only one disruption occurred. The July shipment hit rainy season road damage, delaying port-to-site transport by five days. We immediately activated alternative routing through DRC territory, avoiding critical path impact. The client's project manager later emailed specifically to say this was the most reliable cable supplier they had worked with.
Technical Support
From July to September, we stationed two engineers on site. They addressed three main issues: first, YJV large cable installation in risers—calculating sidewall pressure and pulling tension, recommending top-down installation with fixing clamps every 1.5 meters, successfully completing the 35-level riser in one operation; second, SWA cable termination fabrication—training six local electricians on large-section 500mm² terminations, focusing on steel armor earthing treatment; third, emergency supply—when a level 23 distribution board relocated and needed 300 additional meters of H05VV-F 3×16mm², we mobilized from local backup stock within 48 hours without stopping floor construction.
Acceptance and Operation
Electrical commissioning completed in March 2024, with all testing passed by Société Nationale d'Électricité (SNE) and Bureau Veritas. Infrared thermography showed YJV terminations running 42-48°C and SWA terminations 38-45°C, all within normal range. Insulation resistance exceeded 1000 MΩ throughout, documentation complete.
The building formally commissioned in December 2024. Our January 2025 follow-up with facility manager Bolloré Logistics produced straightforward feedback: three months zero cable faults; H05VV-F flexible cables withstanding repeated bending during office reconfigurations with three zone adjustments completed without sheath cracking; YJV backbone cables running below 45°C sheath temperature at full load, under design limits.
Their only suggestion: for future similar projects, increase H05VV-F 3×16mm² backup stock to 15%, as this large-section flexible cable finds wide use in high-rise distribution and field changes are common.

Our Strengths
This project succeeded not on lowest price, but three concrete advantages.
Complete certification. From 1.5mm² fine wires to 500mm² high-voltage cables, full IEC 60227, IEC 60502, EN 50525 test reports and CE marking. The client used our documentation for international financing application—approved first submission, no delays.
High-rise experience. Multiple African high-rise projects taught us practical realities: tight riser spaces, difficult local logistics, limited electrician skill levels. This experience translated to advance contingency planning, not after-the-fact fixes.
Rapid response. Own production lines for both flexible and high-voltage cables, no supplier coordination needed. Eight-week average delivery, twice as fast as local competitors. On-site problems resolved within 48 hours, not passed around.
Contact Us
For similar high-rise building or large commercial projects requiring IEC-certified comprehensive cable solutions, please contact:
Dongguan GERITEL Electrical Co., Ltd.
Tel/WhatsApp/WeChat: +86 135 1078 4550 / +86 136 6257 9592
Email: manager01@greaterwire.com