DC circuits need breakers that are made for DC. Unlike AC, the current doesn’t drop to zero — so the arc lasts longer and puts more stress on the contacts.
We build our DC MCBs to handle exactly that. Stronger arc chambers, better contact materials, and ratings that match real DC applications.
Tell us about your project, and we’ll help you find the right protection.
Here's a quick look at what our DC MCBs cover.
Share your project requirements with us, and we'll recommend the right solution.
Most MCBs you come across are designed for AC — that’s just how the market has traditionally worked.
But when you put an AC breaker in a DC circuit, the conditions change, especially when a fault happens and the breaker needs to interrupt the current.
AC and DC behave differently when a circuit breaker interrupts a fault.
AC current periodically passes through zero as its waveform changes direction.
When the breaker contacts open and an arc forms, this periodic zero crossing gives a natural chance for the arc to extinguish.
DC current flows continuously in one direction and never drops to zero.
So when the breaker opens, the arc doesn’t have that same natural break — it lasts longer and puts more stress on the contacts.
At first glance, it might seem fine to use an AC MCB in a DC circuit if the voltage and current ratings match. But a breaker’s ability to protect a circuit isn’t just about its normal operating ratings — it’s about what happens during a fault.
When a fault occurs, the breaker needs to open the circuit, control the arc, and complete the interruption safely. In AC, the zero-crossing helps with that. In DC, there’s no zero-crossing to assist. So an MCB that hasn’t been rated and verified for DC conditions isn’t safe to use in a DC circuit, even if the numbers on the label look right.
The arc may be more difficult to extinguish because the DC has no zero crossing point.
A longer arc creates more heat and electrical stress, wearing down the contacts.
In severe cases, the heat can damage the contacts or cause them to weld together.
If the arc isn't controlled, the breaker may not interrupt the fault reliably
DC MCBs are built specifically for DC interruption. The design has to handle the arc without relying on a zero-crossing.
That means the contact system, arc-extinguishing structure, voltage rating, breaking capacity, and polarity configuration all need to be designed for DC conditions.
These elements work together so the breaker can do its job reliably when a fault occurs, not just during normal operation.
DC MCBs are used in a range of systems where DC circuits need protection. The applications below are some of the most common — each with its own requirements for voltage, current, and fault protection.
Solar panels generate DC power, so the circuits between your PV array and inverter operate on the DC side.
A DC MCB protects these circuits against overcurrent and short circuits. Sizing depends on your system voltage, current, and fault level — we can help you match the right breaker to your array.
Battery systems store and deliver DC power, and they can continue feeding current during a fault — which makes proper protection essential.
A DC MCB protects the battery circuit and provides a disconnect point when you need to isolate the system for maintenance or safety.
In a DC distribution panel, one power source supplies multiple branch circuits. A DC MCB on each branch protects that circuit individually.
If a fault occurs on one branch, the breaker trips without taking down the rest of the panel — so other equipment keeps running.
EV charging stations contain DC circuits that need protection just like any other DC installation.
A DC MCB rated for the charger’s operating voltage, current, and fault capacity helps keep the equipment safe and reliable. It’s a simple addition that protects both the charger and the vehicle.
Telecom and communication equipment typically runs on DC power, with multiple branch circuits feeding different loads.
A DC MCB on each circuit provides overcurrent and short-circuit protection, and lets you isolate a faulty branch without shutting down the entire site.
You‘re not just looking for a box of MCBs. You’re looking for an expert who solves your problem, delivers on time, backs up their products, and actually picks up the phone when something comes up. Here‘s what we offer — and what it means for your day-to-day.
We offer technical customization — from rated current and trip settings to internal configurations. You get a breaker that matches your exact circuit design.
CB/CE/RoHS/SAA — fully certified across the board. That means global compliance, smoother customs, and one less thing to worry about when you ship worldwide.
Every MCB goes through full electrical and mechanical testing before it leaves our factory. You get consistent, reliable products, batch after batch, right out of the box.
OEM, ODM, or SKD/CKD — we adapt to your business model, not ask you to adapt to ours. You stay in full control of your brand and your entire supply chain.
We back our products with a 1-year warranty against defects or performance issues. If something isn't right, we make it right — quickly and without hassle.
Samples ship within 48 hours. A dedicated project manager gets back to you within 24 working hours — because waiting on a reply slows everyone down.
Start with a small trial order to test our quality and service before committing to larger volumes. We want you to be confident in our products before you scale up.
Our engineers are available to help with selection, integration, and troubleshooting. You get real answers from real experts — not just a sales rep reading off a spec sheet.
Here's a real-world engineering scenario showing how reviewing PV string conditions helped refine DC MCB selection on a commercial rooftop solar installation.
A commercial warehouse in Queensland was installing a new rooftop PV system to reduce daytime electricity consumption from the grid. The project totaled about 420 kW of PV capacity, distributed across several roof sections.
The system used multiple PV strings connected to string inverters. Each string was a series-connected group of modules, grouped within DC combiner arrangements before connecting to the inverter inputs.
The original design was based on the expected module characteristics and the inverter manufacturer’s input requirements. DC protection devices were initially selected around the anticipated string current and system voltage. At the design stage, the arrangement looked straightforward.
During construction, however, the contractor made several practical adjustments to the string layout. They had to work around roof obstructions, equipment access paths, and the actual location of the inverter cabinets.
Some strings became longer than originally planned. The number of parallel strings connected to several inputs was also adjusted.
None of these changes significantly affected the overall PV capacity. But they did change the electrical conditions that the DC protection devices were expected to operate under.
Before final commissioning, the electrical contractor decided to review the DC protection configuration against the installed system — rather than relying solely on the original design calculations.
The first step was to verify the actual electrical characteristics of the installed PV strings.
The PV modules had a nominal maximum power current of approximately 13 A, with an open-circuit voltage of around 50 V per module under standard test conditions. With 10 modules in series, a typical string operated at roughly 400–450 V DC, and the open-circuit voltage increased further under low temperatures.
The operating current itself wasn’t particularly high. The more important question was whether the protection devices were correctly matched to the actual DC voltage and fault conditions.
The engineering team identified three areas that required closer review.
The system was generally referred to as a “400 V DC PV system” throughout the project. However, the actual open-circuit voltage of a string could approach 500 V DC under certain conditions. This meant the MCB’s DC voltage rating couldn’t be selected simply from the nominal operating voltage — the maximum possible PV string voltage had to be considered.
A single PV string has limited short-circuit current. But when multiple strings are connected in parallel, current from healthy strings can contribute to a fault on another string. A group of four parallel strings, for example, could potentially deliver substantially more fault current to a faulted branch than a single string could provide by itself. The team therefore reviewed the number of parallel strings connected to each protection point, rather than evaluating each string in isolation.
The original protection selection had focused heavily on the string current rating. The commissioning review highlighted that the MCB also needed an appropriate DC interruption capability.
This was particularly important because DC current doesn’t naturally pass through zero the way AC current does. Once a DC arc is established, interrupting it requires the protection device to be specifically designed for the DC circuit conditions. The team reviewed the MCBs against the actual PV voltage, expected current, available fault current, and the manufacturer’s specified DC breaking capability.
Rather than changing the PV modules or inverter configuration, the contractor revised the DC protection selection for the affected string circuits.
The replacement devices were selected specifically for photovoltaic DC applications and verified against the maximum expected system voltage. Their DC breaking capacity and pole configuration were also checked against the installation requirements.
The string current remained within the original design range, so there was no need to increase the protection rating simply because the strings were longer. This was an important part of the review — increasing the MCB rating wouldn’t have solved the underlying protection-selection issue.
Instead, the contractor kept the protection rating appropriate for the PV string and conductor while ensuring the device itself was suitable for the DC voltage and fault-interruption requirements.
The revised selection process looked at the complete chain:
PV module characteristics → string voltage → string current → number of parallel strings → cable length → available fault current → MCB voltage rating → DC breaking capacity
The contractor also checked the polarity and connection arrangement of the DC MCBs before installation. This was particularly important because the manufacturer specified different connection requirements depending on the pole configuration and DC application.
After installing the new protection devices, the contractor carried out the normal commissioning checks for the PV DC circuits — polarity verification, insulation resistance testing, string voltage measurements, continuity checks, and verification of the protective-device configuration.
The measured string voltages were consistent with the expected design values, and the DC protection devices were confirmed to be suitable for the installed operating conditions.
The revised protection arrangement didn’t require any major changes to the PV system. The modules, string configuration, cable sizes, combiner arrangements, and inverters remained essentially unchanged. The main improvement came from matching the DC MCB specification more closely to the actual electrical conditions of the installed system.
The project also highlighted an important lesson for PV system design. A DC MCB cannot be selected simply by looking at the PV string’s operating current. For photovoltaic applications, the protection device needs to be considered against several conditions at the same time:
The MCB’s DC voltage rating needs to accommodate the maximum possible string voltage, including the effect of low temperatures on PV open-circuit voltage.
The protection arrangement needs to consider not only the current from an individual string, but also the potential contribution from parallel strings under fault conditions.
The device needs to be capable of interrupting the expected DC fault current at the applicable system voltage.
Pole arrangement, polarity, wiring method, and manufacturer-specific connection requirements all need to be checked as part of the installation.
The final commissioning review shifted the team’s approach from:
“The string current is 13 A, so a suitable MCB should simply be around that rating.”
to:
“The MCB needs to be suitable for the complete PV circuit — including maximum DC voltage, fault current, breaking capacity, and installation configuration.”
PV systems operate under conditions that are different from conventional AC distribution. DC voltage can remain present whenever the PV modules are illuminated, and multiple parallel strings can contribute to fault conditions.
For this reason, selecting a DC MCB for photovoltaic applications should involve more than matching the breaker rating to the normal string current. A proper review should consider:
Voc × temperature correction → operating current → parallel strings → cable characteristics → prospective fault current → DC voltage rating → DC breaking capacity
The right protection device isn’t simply the one with the correct ampere rating. It’s the one whose electrical characteristics match the actual PV circuit it’s protecting.
The final protection selection was not driven by the nominal string current alone. We had to look at the maximum DC voltage, parallel-string fault contribution, and the breaker's actual DC interruption capability before confirming the final configuration.
— David Chen
Electrical Project Engineer
Quick answers to the most common questions we get about DC MCBs.
In a DC circuit, the current never drops to zero, so the arc lasts longer and puts more wear on the contacts. That means the same breaker will typically have a shorter electrical life when used in DC than in AC.
The exact difference varies by design, so it’s always a good idea to check the datasheet for the rated electrical life under DC conditions. If your application involves frequent switching, look for a breaker with a higher mechanical and electrical operation rating.
Some people assume that putting two 250V DC breakers in series gives you a 500V rating. That’s not how it works, and it’s not a safe practice.
The voltage rating of a DC MCB comes from its internal arc chamber design — the number of arc plates, the magnetic blow-out coil, and the venting structure. These are engineered for a specific voltage.
When you put two breakers in series, there’s no guarantee that the voltage will split evenly. One breaker may end up handling most of the voltage, which pushes it beyond its limits.
If your system needs a higher voltage rating, the right solution is to use a breaker that’s actually rated for it.
The DC MCB goes on the DC input side of the inverter — between the PV array and the inverter. There are a few reasons for this.
First, the DC cables from the panels to the inverter need protection, and the inverter can’t protect that section of the circuit.
Second, the MCB provides a safe way to isolate the inverter for maintenance or if an internal fault develops.
Third, in systems with multiple parallel strings, a DC MCB on each string prevents current from healthy strings from flowing back into a failed one.
Visually, breakers from the same series often look nearly identical. You can’t reliably tell them apart by size, color, or shape.
The only reliable way is to read the markings on the breaker body. Look for the voltage rating — a DC MCB will say something like “250V DC” or “500V DC,” while an AC MCB will show “230V AC” or “400V AC.”
Also check the standard reference: DC MCBs typically comply with IEC 60898-2 or IEC 60947-2, while standard AC MCBs follow IEC 60898-1. Some breakers also use the ⎓ symbol for DC and the ~ symbol for AC.
When in doubt, always check the nameplate.
No. A 2-pole DC MCB has a mechanically linked operating mechanism — both poles are controlled by one handle and open and close together. It’s designed to disconnect both the positive and negative conductors of a single circuit at the same time.
If you try to use it for two independent circuits, a fault on one circuit will trip both poles and shut down the other circuit as well, even if it’s operating normally. That could mean unexpected downtime for critical equipment.
The correct use is one 2-pole MCB for one circuit — positive on one pole, negative on the other.
The higher cost comes down to the internal design and materials. In AC circuits, the current crosses zero naturally 50 or 60 times per second, which helps extinguish the arc. DC has no zero-crossing, so the breaker has to handle the arc on its own.
That requires a stronger magnetic blow-out coil to drive the arc into the chamber, more arc plates to split and cool it, more erosion-resistant contact materials, and more precisely engineered arc chambers and venting paths.
These extra materials and tighter tolerances all add to the production cost. You’re paying for a breaker that’s actually designed for DC — not one that’s adapted from AC.
Every DC system has different protection requirements. Share your project details with us to find the right DC MCB for your system.
