A two-, three- or four-pole breaker is not automatically approved for an improvised series connection. Buyers need the exact catalog number, approved wiring diagram and ratings for the actual DC system. Pole count alone is not voltage or interrupting evidence.
Define the source, maximum voltage, grounding, current direction, prospective fault current and isolation function before requesting a breaker. This guide structures that evidence review. It does not provide installation instructions, reproduce paid standard tests or create a universal formula for adding voltage ratings across poles.
Define the DC system before choosing a pole count
State whether the source is photovoltaic, battery, charger, motor drive or another DC bus. Record the maximum voltage using the applicable worst case, not only a nominal label. For a PV circuit that can include cold-weather open-circuit voltage; use the PV cold-weather voltage guide to organize those inputs. For a battery circuit, identify the maximum charging or regenerative condition required by the system designer.
Provide a single-line diagram showing whether the circuit is grounded, ungrounded or midpoint-grounded. Identify normal and reverse current and state which conductors need protection or must open for isolation. These questions can produce different wiring decisions.
Include the prospective fault current at the breaker's location and the basis used to establish it. Voltage suitability does not prove adequate interruption. The DC breaker trip-curve and interrupting-rating guide covers that separate selection evidence.
Identify the product standard and application category
IEC 60947-2:2024 is the current sixth edition for industrial circuit breakers. Its public scope covers devices intended for operation by instructed or skilled persons with main circuits up to 1,000 V AC or 1,500 V DC. Those are scope ceilings, not a rating for every breaker, and the public page supplies no universal series-pole arrangement. IEC 60947-2:2024 public scope.
IEC 60898-2:2016 has a narrower public scope for single- and two-pole breakers used in household and similar installations. It states limits of 220 V DC for single-pole and 440 V DC for two-pole devices, 125 A rated current and 10 kA DC short-circuit capacity. An RFQ should therefore name the applicable product standard rather than treating all DC breakers as interchangeable. IEC 60898-2:2016 public scope.
For a North American project, distinguish the general molded-case category from application-specific evidence. UL 489 Edition 14 is active and has public scope ceilings of 1,500 V DC and 6,000 A; neither is an individual catalog rating. UL 489 Edition 14 public scope.
UL 489B is active for specified photovoltaic molded-case equipment up to 1,500 V DC, and its public scope expressly excludes circuit breakers and switches intended for battery circuits. A PV marking therefore cannot be transferred to a battery application without separate applicable evidence. UL 489B public scope.
Require the exact approved connection diagram
Ask for the complete breaker part number and an approved diagram showing terminal numbers, series links, line/load orientation and polarity. Identify whether links are factory installed, a named kit or field-made under published instructions. Request the specified conductor range, link size, torque and accessories.
UL Solutions' current molded-case breaker marking guide states that a multi-pole PV breaker is intended for individual circuits on each pole unless it is specifically marked with a diagram or wording that details the correct electrical connections. The same public guide describes connection-diagram and application markings for battery-power-supply breakers. This directly supports holding a quote that shows only a pole count and overall voltage claim. UL Solutions Molded Case Circuit Breaker Marking and Application Guide.
Do not assume every pole has the same protective release or that a common handle proves the required protection. Require the manufacturer or qualified designer to identify how the topology provides protection and simultaneous operation, and retain the diagram revision.
Do not multiply a per-pole voltage by arithmetic
A common shortcut is to multiply a perceived per-pole voltage by the number of poles. That does not establish a tested rating, permitted grounding arrangement or breaking capacity. Require a rating table or instruction for the complete device in the exact connection.
For its ComPacT NSX DC PV application, Schneider says the minimum series-pole count depends on system voltage and device voltage rating per pole. A commissioning page gives a product-specific 1,000 V DC PV example using four series poles, two per polarity, and discusses temperature rise. This named example is not a generic four-pole rule. Schneider Electric ground-fault guidance and ComPacT NSX DC commissioning guidance.
Eaton's May 2025 Power Defense catalog provides a different named example: its identified DC breakers use three poles in series on the ungrounded leg for 600 V grounded systems, with 500 V stated for Power Defense frame 1. The example reinforces why a buyer must obtain the diagram for the exact manufacturer, frame and grounding system rather than copy another product's topology. Eaton 2025 molded-case circuit-breaker catalog, page V4-T2-111.
Make grounding and fault paths explicit
Grounding affects which poles can be exposed during a fault. In an ungrounded PV system, a first insulation fault can change the conditions faced by a later fault. Schneider's product guidance warns that a double ground fault can involve fewer than the normally required series poles and calls for detecting and clearing the first insulation breakdown without delay. Treat this as a system-design issue governed by the relevant installation requirements and the selected equipment, not as a field-testing instruction.
Ask the system designer to approve the one-line and fault assumptions. Require the breaker supplier to state which published connection applies. A diagram for an ungrounded system should not be silently reused for a grounded or midpoint-grounded circuit.
Review polarity and current direction separately
A documented series topology does not by itself prove bidirectional interruption. Preserve every +, −, line and load marking and state the normal and possible reverse-current directions. Ask for an explicit directional or bidirectional statement for the exact catalog number and operating condition.
Use the DC breaker polarity and line/load guide for that review. Do not rotate a diagram, reverse terminals or infer suitability from an AC drawing without manufacturer evidence.
Compare quotations with one evidence worksheet
The buyer should issue the same system inputs and requested documents to every bidder.
On small screens, swipe or scroll sideways to read every column. Keyboard users can focus the table and use the arrow keys.
| RFQ input | Why it changes the decision | Evidence required from the bidder |
|---|---|---|
| Source and application | PV, battery and other DC categories can have different approvals and behavior | Exact application marking, standard and certification entry |
| Maximum DC voltage | The documented topology must cover the applicable worst case | Rating table for the exact part and connection |
| Grounding topology | Fault paths and involved poles can change | Buyer one-line plus manufacturer-approved breaker diagram |
| Current direction and polarity | Some DC devices have terminal or direction restrictions | Nameplate markings and directional statement |
| Prospective fault current | Voltage rating does not establish interruption | Applicable breaking-capacity evidence at the specified voltage |
| Protection and isolation goal | Protected poles and opened conductors are separate design questions | Documented release arrangement and isolation statement |
| Series links and accessories | Field links and terminals are part of the configuration | Named link kit, instructions, conductor range and torque |
| Ambient and enclosure | Series connections and enclosure heat can affect loading | Product-specific temperature and derating documentation |
Do not accept a certificate that omits the quoted catalog number or configuration. Confirm that required certification evidence covers the offered application, voltage, current, poles and accessories.
Review an invented bidder comparison
The following offers are fictional and are not real supplier claims, test results or SINAWATTS recommendations. Bidder A offers a four-pole device and states that four contacts “add up” to the project voltage. It supplies an AC data sheet but no DC connection diagram, grounding limitation or fault rating at the specified voltage. Hold the offer.
Bidder B returns the exact DC catalog number, application marking, one approved diagram matching the buyer's grounding system, the required link kit, polarity and line/load information, and breaking-capacity and ambient data for that configuration. Review it against the project criteria. Complete evidence makes the offer assessable; it does not replace the responsible designer's approval.
Close the RFQ with controlled documents
Request a nameplate or marking image, current data sheet, certification reference where required, manufacturer connection diagram, link/accessory part numbers and installation document. Link them to the one-line, system voltage, grounding, fault-current study and isolation requirement. Define who approves a substitution or wiring revision.
Send the source type, maximum voltage, grounding diagram, current direction, prospective fault current, isolation function, ambient conditions and candidate breaker part with the enquiry. Require the bidder to return the exact marked connection and applicable rating evidence.
Send a DC breaker configuration RFQ
Buyer FAQ
Can any multi-pole AC breaker be wired in series for DC?
No. Use a device with a documented DC rating and the manufacturer's approved connection diagram for the exact catalog number, application and grounding system. Pole count or mechanical ganging does not create that evidence.
Can I multiply the per-pole voltage by the number of poles?
Do not use that arithmetic as a product rating. Require a marked or published system-voltage and breaking-capacity rating for the complete breaker in the exact series connection.
Must both DC polarities pass through breaker poles?
That depends on grounding, protection, isolation and the manufacturer-approved topology. State those inputs in the RFQ and have the qualified system designer approve the resulting one-line and breaker diagram.
Can a UL 489B PV breaker be used in a battery circuit?
UL 489B's public scope expressly excludes breakers intended for battery circuits. Request application evidence and markings that cover the battery system and exact device rather than relying on a PV rating.