400A Underhead Supply Upgrades
Who Needs a 400A Underground Supply?
400A underground installations are the solution for high-demand sites where capacity, reliability, and clean infrastructure all matter.
Contact US- Large commercial and industrial developments requiring high-capacity underground supply
- Cold storage and refrigeration-heavy industrial operations
- Sites transitioning from Temporary Builder's Supply to permanent 400A underground connection
- Strata complexes and mixed-use developments with significant common area demand
- Data centres and server farm facilities
- Prestige commercial developments requiring clean, aerial-free high-capacity supply
- EV fleet charging depots and transport hubs
- Large hospitality and entertainment venues
What a 400A Underground Supply Actually Is
A 400A underground supply delivers high-capacity power through service mains run in conduit from the network pit to your building or distribution pillar — completely below ground. Underground 400A installations eliminate aerial infrastructure entirely and are the preferred solution for large commercial and industrial developments where reliability and aesthetics matter.
At 400A, underground installations require correctly rated cable, correctly designed pit and conduit infrastructure, and careful coordination with the network distributor's civil specifications. This is complex work — civil, electrical, and network all running simultaneously.
What We Install — The Complete 400A Underground System
Every component of the installation, managed end to end by High Demand Electrical.
- Underground conduit and pit infrastructure: Trench excavation, conduit installed to network specification, reinstatement
- 400A underground service mains: Correctly rated cable pulled through conduit from network pit
- Parallel underground consumer mains runs (dual 200A) where required to achieve 400A total capacity
- Private pillar or pit supplied and installed where required at the property boundary
- 400A earthing system: Earth stake, water pipe bonding, MEN link
- CT metering upgrade: Coordinated with network and energy retailer
- Private pit supply and installation (where required)
- Network pit connection: Terminated and made off to distributor standard
- 400A consumer mains from supply point to main switchboard or distribution pillar
- 400A main switchboard or distribution pillar: Commercial-grade, correctly rated for the load
- NOSW lodgement and CCEW issued on completion
Our Energy Providers
Authorised by Sydney's major networks
All Three Networks — Ausgrid, Endeavour Energy & Essential Energy
Accredited with every network distributor operating across Greater Sydney and NSW. One company handles the entire network process regardless of your location.
Ausgrid, Endeavour Energy, Essential Energy — accredited with all three
Maximum demand calculation prepared in-house
Network application submitted on your behalf
Network capacity assessment and civil works specification coordinated
Level 3 design managed where network construction is required
Level 1 ASP construction coordinated where required
The Process — From Application to Energisation
From maximum demand calculation through to energisation — here’s exactly how High Demand Electrical manages a 200A underground upgrade end to end.
- Maximum Demand Calculation
We prepare a certified maximum demand assessment for your site. At 400A underground, this calculation drives the cable sizing, conduit specification, and pit design — it's the technical foundation of the entire project. - Network Application
We prepare and submit your supply upgrade application to your distributor on your behalf — including maximum demand calculation, site details, civil works specification, and proposed 400A underground supply configuration. - Network Assessment
The distributor assesses network capacity and reviews the underground connection design. 400A applications almost always trigger a full network assessment — and many will require network construction. - Level 1 / Level 3 Coordination (If Required)
Where additional network capacity is needed, we coordinate Level 3 design and Level 1 ASP construction through our managed supply chain. Where civil works in the street or public domain are required, we manage that too. You deal with one company throughout. - Level 2 Installation
Our Level 2 ASP team completes the full 400A underground installation — civil works, conduit, cable, pit connections, consumer mains, earthing, switchboard or distribution pillar, and CT metering. NOSW lodged on completion. - Energisation
Your 400A underground supply is energised, tested, commissioned, and signed off. All compliance documentation issued.
Why Choose High Demand Electrical?
Experience, accreditation and a fixed-price approach that removes uncertainty from complex Level 2 underground projects.
Complementary Level 2 ASP Services
200A Overhead Supply Upgrades
Underground Service Mains Installation
Switchboard Upgrades
Single to Three Phase Upgrades
Smart Meter Upgrades
Private Pillar and Pole Installation
Get Your 400A Underground Upgrade Quote Today
High Demand Electrical - 200A Underground Upgrades
FAQs
Answers to the questions we hear most from Sydney homeowners, builders, and site managers.
A 400A underground upgrade involves excavating trenches from the network pit to your building, installing correctly rated conduit and cable (often parallel dual 200A runs), connecting at the network pit to distributor standard, and terminating at your switchboard or distribution pillar. Civil reinstatement is included.
Yes. Where a single 400A rated cable is not specified by the network, 400A is commonly achieved via dual parallel 200A underground consumer mains runs — each correctly rated and terminated. We design the installation to match the network's approval.
Frequently, yes. At 400A, the existing network often needs augmentation before the connection can proceed. We manage this through our Level 3 design and Level 1 construction partners — you deal with one company throughout.
Yes. We coordinate and manage all civil works — trenching, conduit, pit installation, and reinstatement — as part of the project scope. One quote covers civil and electrical.
It depends on the civil scope, network approval timeline, and whether network construction is required. We'll give you a realistic project timeline at the quoting stage.
Testimonials
"Chris was the professional, punctual and his services are exceptional. Chris re-wired the entire property, chased the electrical work in the bathroom and kitchen areas, left a clean and tidy environment and his open communication and dialogue was a welcomed experience.
When he quoted an arrival time, he was there. He talked me through what he was doing, and provided feedback/suggestions on how to tackle any issues. I felt part of the process, as opposed to being another Customer.
A pleasure to deal with, and I recommend his services. I'll be definitely calling him again with any electrical work I need done."
"Chris and his team are a professional outfit who were friendly and very helpful with any questions I had about the work they were doing. They completed their work promptly and to a high standard of quality. Would definitely use them again for any future electrical works!"
"HDE did a great job at our place, Chris was highly responsive, professional and a master of his craft; there was no challenge too great. I would highly recommend High Demand Electrical."
"Chris and his team did a great job. Excellent customer service all round. Great communication, very thorough and professional. Took the time to get the job done right and cleaned up afterwards Would hire again and definitely recommend. A+ job."
"Great electricians- very professional and efficient with doing the electricals for our kitchen renovations & new lighting in our apartment. Gave good suggestions as well for kitchen cupboard lighting. Highly recommend them."
Our Partners
Powering Your Needs with Expertise
If you’re looking for a reliable, experienced, and prompt electrician, look no further than High Demand Electrical. We cater to all your electrical needs, from routine maintenance to emergency repairs and complete system installations. Our skilled team is committed to providing professional service that ensures your electrical systems run smoothly. Whether it's a small task or a large project, give us a call today. Let us meet all your electrical demands with the quality and reliability you deserve.
