Hybird breakers generate heat under load. Panel builders and installers must account for this when sizing enclosures and planning ventilation. This article provides guidance on heat dissipation calculations.
Why heat matters
Every breaker dissipates power (in watts) as heat when carrying current. The total heat dissipation of all devices in a panel determines the enclosure's internal temperature rise. Exceeding the enclosure's thermal capacity can cause breakers to trip prematurely, accelerate component ageing, and in extreme cases pose a safety risk.
Heat dissipation per breaker
Heat dissipation increases with load current. Refer to the RCBO and MCB specification articles for the detailed heat dissipation tables, which show watts dissipated at each current rating and load level.
As a general guide, a fully loaded breaker at its rated current dissipates between 2-8 watts depending on the type and rating. Multiply by the number of breakers to estimate total panel heat dissipation.
Calculation example
For a panel with 20 Hybird RCBO breakers, each rated at 16A and expected to operate at approximately 75% load:
Look up the heat dissipation at 12A (75% of 16A) in the RCBO spec table.
Multiply by 20 breakers.
Add the controller, PSU, and UPS power dissipation.
The result is the total heat that the enclosure must dissipate.
Enclosure sizing
Enclosure manufacturers specify a maximum internal heat dissipation (in watts) for each enclosure size, based on the enclosure material, surface area, and whether ventilation is provided. Select an enclosure where the total calculated heat dissipation is comfortably within the manufacturer's rating.
If the calculated heat dissipation exceeds the enclosure's natural convection capacity, consider:
A larger enclosure.
Adding ventilation openings (with appropriate IP-rated filters).
Adding forced ventilation (fans).
Reducing the number of breakers per enclosure by splitting across multiple panels.
Temperature derating
Breakers are rated for operation at a reference ambient temperature (typically 30°C). If the ambient temperature where the panel is installed is higher, or if the internal panel temperature rises above the reference, breakers may need to be derated (i.e., their effective maximum current rating is reduced). Consult the breaker specifications for derating factors.
Best practices
Do not assume all breakers will run at full rated current - use realistic load estimates for your calculation.
Leave some thermal margin (20-30%) above your calculated heat dissipation when selecting an enclosure.
For outdoor installations, account for solar heating of the enclosure in addition to internal heat dissipation.
Monitor breaker temperatures in Hybird OS after commissioning to verify actual temperatures are within acceptable range.
Need help?
Technical support: [email protected]
Billing and invoicing: [email protected]
Sales and partnerships: [email protected]
Phone: +45 3020 4900