High Current Power Distribution Box Rated to 800A
Current rating is where a distribution box is won or lost. An 800A box has to carry 800A continuously without exceeding its temperature limits, and it has to survive the fault current the upstream supply can deliver until the protection clears it. Those two figures - rated current and short-circuit withstand - decide the busbar, the breaker and the enclosure size.
We build high current boxes from 250A up to 800A on the same design logic: a main MCCB sized to the supply, a copper busbar sized to the full current, and outgoing ways split so no single circuit carries more than its own protection allows.
Busbar, Breaking Capacity and Heat
At 800A, details that are irrelevant on a 63A board become the whole design: busbar cross-section, joint preparation, cable lug size, ventilation and the space around the breaker.
- Copper busbar sized for 800A continuous, with defined torque values
- Main MCCB with breaking capacity matched to the prospective fault current
- 400A camlock or powerlock ways, 16A to 63A outlets
- Temperature rise verified against IEC 61439-1 limits
- Forced or natural ventilation sized for the actual dissipated power
Current Rating Selection Guide
| Rated Current | Typical Use | Typical Outgoing |
|---|---|---|
| 250A | Small venue, single hall, medium site | 16A / 32A CEE, 6 to 8 ways |
| 400A | Concert stage, mid-size event, plant hire | Socapex 19-pin, 32A CEE |
| 630A | Large festival, film set, temporary site | 400A camlock, socapex, 63A CEE |
| 800A | Stadium show, large outdoor event, shipyard | 400A camlock / powerlock, 63A to 125A |
800A Unit Specifications
| Parameter | Options |
|---|---|
| Rated Current | 630A / 800A, or 250A to 800A to order |
| Incoming | 400A / 630A camlock, powerlock, or busbar |
| Main Protection | MCCB with adjustable trip, breaking capacity to fault level |
| Busbar | High-conductivity copper, sized for continuous 800A |
| Outgoing | 400A camlock ways, 16A / 32A / 63A CEE |
| Enclosure | HDPE, stainless or steel, IP54 to IP67 |
| Metering | Per-phase V/A, optional kWh and power quality |
| Ventilation | Natural or fan assisted, sized to dissipated power |
| Documentation | Single-line diagram, busbar schedule, test record |
| Standards | IEC 61439-1 / -2, IEC 60309, IEC 60529 |
How the Current Rating Is Verified
Frequently Asked Questions
How do I know whether I need 630A or 800A?
Add the continuous load of everything that may run together, then allow for the duty cycle and a margin. If the calculated current sits above roughly 80 percent of a 630A rating, or the supply is 800A and must be distributed in full, specify 800A. The upstream supply and its protection must be confirmed at the same time.
What cable suits an 800A feed?
Single-core cables in parallel are common at this level, sized for the installation method and ambient temperature, with the protective conductor sized to the same fault level. The final size should be confirmed against the site conditions and the local wiring regulations.
Does a higher rating always mean a bigger enclosure?
It needs more copper and more heat dissipation, so usually yes. Ventilation and busbar support spacing are designed together, which is why an 800A box is not simply a 400A box with a bigger breaker inside.
Send Your Load Schedule
Share the incoming supply, prospective fault current and the list of outgoing ways. We will confirm the busbar, breaker selection and a factory price, and return a drawing for approval before production.
- Busbar cross-section and joint design are checked against the continuous current, with torque values recorded at assembly.
- The assembly is designed to IEC 61439-1 and IEC 61439-2, including temperature-rise verification and short-circuit coordination with the selected MCCB.
- Breaking capacity is selected against the prospective fault current at the connection point, not against the box rating alone.
- Routine tests on every unit: protective earth continuity, insulation resistance, RCD trip time, phase rotation and a functional check of each way.
- A busbar schedule, single-line diagram and test record are supplied with the unit, so the installation can be verified by the site engineer.
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