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DC Distribution Box Manufacturer

PV, ESS, EV charging, telecom & industrial DC distribution up to 1500 VDC

A DC distribution box—also called a DC combiner box, DC junction box, or DC distribution panel—collects multiple DC inputs, protects each circuit, and delivers a single, organized output to inverters, battery racks, DC chargers, telecom rectifiers, or DC drives. A well-engineered box integrates over-current protection (fuses or breakers), isolation, surge protection, busbars, and monitoring in an IP-rated enclosure for reliable service in solar PV, energy storage (ESS), EV charging, telecom (−48 V), and industrial DC systems.

Protection and switchgear inside the box often include:

DC circuit breakers for branch or feeder protection — see /dc-circuit-breaker-manufacturer/
DC fuses (10×38, 14×51, 22×58, NH gPV, aR/gR) — see /dc-fuse-manufacturer/
DC SPDs (Type 1/2/1+2 for PV/ESS) — see /dc-spd-manufacturer/
DC isolator switches / switch-disconnectors — see /dc-isolator-switch-manufacturer/

Product Portfolio (what we build)

PV DC combiner boxes (string/array level): 600 / 1000 / 1500 VDC, 4–48 strings, fuse-protected inputs, Type 2 or Type 1+2 SPDs, main DC isolator or MCCB, optional string monitoring.
PV array junction boxes (rooftop micro-combiner, IP65/IP66): MC4 or gland entries, touch-safe fuse holders, rotary lockable handle.
ESS DC distribution panels: high-current busbars, feeder MCCBs, battery rack disconnects, Type 1+2 SPDs, shunts, and auxiliary contacts for BMS/EMS.
Telecom −48 V DC distribution units (PDU): MCB rows, low-voltage SPDs with low Up, shunts/meters, alarm relays.
EV charger DC distribution cabinets: cabinet-level disconnect, feeder protection, SPDs, maintenance isolators.
Custom/OEM: special layouts, pre-terminated harnesses, heater/anti-condensation kits, viewing windows, custom labels & QR traceability.

Architecture & Components (inside a modern DC box)

Inputs: cable glands or MC4 bulkheads, strain relief, ferrules, touch-safe terminals.
Branch protection: gPV fuse holders (10×38/14×51/22×58, NH) or DC MCB/MCCB per string/feeder.
Main protection & isolation: door-interlocked switch-disconnector or MCCB with padlockable handle.
Surge protection: Type 1/2/1+2 DC SPDs (MOV or MOV+GDT hybrids) in +/−→PE and +→− modes for PV/ESS.
Busbars & links: tin-plated copper bars, finger-safe shrouds, adequate clearances/creepage for 1000–1500 VDC.
Monitoring & alarms: string current sensors (Hall-effect), shunts, DC metering, temperature/humidity sensing, dry-contact alarms (NO/NC) tied to SCADA/EMS.
Enclosure: powder-coated steel or UV-stable polycarbonate; IP65/IP66 outdoor options; gland plate, labeling kit, torque chart inside the lid.

Selection Guide (long-tail, practical)

System voltage (VDC): choose boxes and components rated for 1000 VDC or 1500 VDC as required; observe any series-pole instructions for higher voltages.
Strings/feeders & current: number of inputs, max string Isc, combiner output current, and busbar ampacity with thermal margin.
Protection method: gPV fuses vs DC MCBs for strings; MCCB for feeders; ensure selective coordination upstream.
SPD strategy: Type 1 at LPZ boundaries; Type 2 near inverters/ESS; consider Type 1+2 at exposed sites.
Isolation & LOTO: door-interlocked isolator or MCCB with red/yellow handle, padlockable OFF, visible isolation.
Environment: IP66 for rooftop PV; gasketed lids, drain/vent options; UV-stable plastics or painted steel; ambient & derating.
Wiring & entries: gland sizes, MC4/bulkhead count, cable cross-sections, torque specs, short, straight internal routing.
Monitoring: string-level current/voltage, bus current via shunt, contact outputs to PLC/EMS; consider remote status for fuses/SPDs.
Labels & documentation: string IDs, polarity arrows, wiring diagram, torque table, QR for BOM/traceability, maintenance log.

Typical Configurations

1500 V PV string combiner: 16–24 fused inputs (10×38 gPV), Type 2 or Type 1+2 SPD, door-interlocked DC isolator, tin-plated busbars, shunt + analog meter, gland plate, IP66.
ESS DC feeder panel: main MCCB, multiple feeder MCCBs to battery racks/inverter DC bus, Type 1+2 SPD, shunt trip & aux contacts, thermal sensor kit, IP54/55.
Telecom −48 V PDU: dual-source inputs with changeover, rows of DC MCBs, low-Up SPDs, shunts, common alarm relay, front-accessible fuses.

Installation Best Practices

Mount close to the equipment (inverter DC input, battery racks) to minimize cable length and surge let-through.
Keep internal conductors short and straight; avoid loops; observe minimum bend radius; torque to spec.
Separate power and signal wiring; bond PE to local earth bar; maintain clearances & creepage for 1000–1500 VDC.
Verify polarity and line/load orientation; apply supplied labels; record string IDs/torques in the log sheet.
Commissioning checklist: insulation/IR, polarity, torque, SPD status, isolator operation, alarm contact test, functional current checks.

Testing & Compliance (what you’ll see on the nameplate)

IEC 61439-1 & IEC 61439-2 — general rules and specific requirements for low-voltage switchgear and controlgear assemblies; applicability up to 1 500 V DC for assemblies like DC distribution/combiner boxes. IEC Webstore+1 ANSI 网店
IEC 61643-31 — DC/PV surge protective devices up to 1 500 V DC (selection and test methods for Type 1/2/1+2). IEC Webstore
IEC 60947-3 — switches, disconnectors, switch-disconnectors, and fuse-combination units up to 1 500 V DC (for the box’s main isolator). IEC Webstore+1 标准机构
IEC 62208 — empty enclosures for low-voltage switchgear assemblies (enclosure tests and ratings). IEC Webstore VDE Verlag
UL 1741 (PV combiner/DER equipment) and/or UL 508A (industrial control panels) for North America, depending on the application. UL Standards Online+1

Authoritative external links (DoFollow)

IEC 61439-1 (general rules): https://webstore.iec.ch/en/publication/32338
IEC 61439-2 (assemblies to 1500 V DC): https://webstore.iec.ch/en/publication/30043
IEC 61643-31 (DC/PV SPDs): https://webstore.iec.ch/en/publication/26931
IEC 60947-3 (switch-disconnectors): https://webstore.iec.ch/en/publication/59785
IEC 62208 (empty enclosures): https://webstore.iec.ch/en/publication/67906
UL 1741: https://www.shopulstandards.com/ProductDetail.aspx?productId=UL1741_3_S_20210928
UL 508A: https://www.shopulstandards.com/ProductDetail.aspx?productId=UL508A_3_S_20180424

Why work with a custom DC distribution box manufacturer

Tailored string/feeder counts, busbar ampacity, 1000/1500 VDC insulation distances, device brands, and layouts to your EPC standards.
Choice of gPV fuses vs DC breakers, Type 1/2/1+2 SPDs, door-interlocked isolators, shunts/meters, and alarm relays.
Outdoor-rated IP66 combiner boxes with UV-stable enclosures and heater/vent options; indoor ESS cabinets with maintenance space.
Complete documentation package: BOM, wiring diagram, torque table, test sheet, QR traceability; support for IEC/UL file submissions.
Fast lead time, OEM branding, serial labeling, spare-parts programs.

Request a custom quote

Send your VDC, number of strings/feeders, max Isc and output current, SPD type (1/2/1+2), preferred protection (fuse/MCB/MCCB), isolator requirement, enclosure rating (IP65/IP66), wiring/entry details, and monitoring/alarm needs.

FAQ

Q1: What’s the difference between a DC distribution box, combiner box, and junction box?

All are DC enclosures for collection and protection. A combiner box focuses on string aggregation (PV), a junction box is simpler with terminaling/splicing, while a distribution box/panel adds feeders, isolation, SPDs, and monitoring.

Q2: How do I size a 1500 V PV DC combiner box?

Count strings (e.g., 24), choose gPV fuses per string based on Isc and temperature, select Type 2 or Type 1+2 SPD, size the output busbar and main isolator/MCCB for combined current, and confirm clearances/creepage for 1500 VDC.

Q3: When should I use fuses vs DC breakers on strings?

gPV fuses are compact and fast for strings; DC MCBs allow reset and visual pole isolation. Choose based on maintenance philosophy and coordination with the main device.

Q4: Do I need both common-mode (±→PE) and differential (＋→−) SPDs?

Often yes in PV/ESS. ±→PE addresses lightning coupling to earth; ＋→− protects electronics. Many boxes implement both modes.

Q5: What enclosure rating do I need for rooftop PV?

Typically IP66 with UV-stable materials, drain/vent options, and sealed glands. Indoor ESS or inverter rooms may use IP54–IP55 metal cabinets.

Q6: Which standards apply to DC distribution/combiner boxes?

Assemblies are commonly built to IEC 61439-1/-2, with IEC 62208 for enclosures, IEC 61643-31 for DC SPDs, and IEC 60947-3 for the isolator. In North America, look for UL 1741 (PV) and/or UL 508A (industrial panels).

Q7: How is string monitoring implemented?

Hall-effect sensors or shunts measure string/bus current; a controller aggregates data and drives dry-contact alarms to SCADA/EMS.

Q8: How do I minimize surge let-through (effective Up) at the inverter?

Place the SPD close to the inverter input, short and straight leads, bonded PE bar, and decoupling distance from upstream SPDs where required.

Q9: Can you integrate a door-interlocked main isolator?

Yes. We offer switch-disconnectors or MCCBs with red/yellow padlockable handles, meeting LOTO practices.

Q10: What documentation is supplied with each box?

BOM, wiring diagram, torque table, verification tests (IR, dielectric, functional), labels/IDs, and QR traceability. OEM file packs are available for IEC/UL submissions.

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