Why DC breaking is harder
Alternating current reverses direction and passes through zero amps many times per second, which helps extinguish arcs inside a breaker’s interrupter. Direct current from PV modules is continuous in polarity during production; arcs can persist and damage contacts if the device is not designed and tested for DC voltage and current.
An AC MCB marked 230/400 V AC may fail to clear a DC fault at comparable voltage, leaving a sustained arc — fire risk in combiner boxes and rooftop arrays common across Lahore housing societies and factory rooftops. Solar designers therefore specify DC MCBs (or PV-rated fuse/disconnect solutions) on the DC side, and ordinary AC MCBs/MCCBs on the inverter AC output side.
GlobalPlus carries DC MCB options such as NC-100H and NTS-63 class products alongside standard AC MCBs like GY-63. Do not assume “63A is 63A” across AC and DC labels — voltage, poles, and polarity markings matter.
String design, polarity, and cable
Match the DC breaker to maximum system voltage and string current (including irradiance and temperature extremes your designer uses). Observe polarity markings on DC devices — incorrect wiring can defeat the interrupting design. Use appropriately rated solar or DC cable where specified; random PVC lighting wire on hot rooftop runs is a false economy.
Keep DC and AC segregation clear in the enclosure: separate trunking, labels, and gland plates reduce service mistakes when someone later “just adds a breaker.” Pair cable size with both the DC MCB rating and the module Isc/Imp calculations so neither copper nor breaker is the weak surprise.
For hybrid sites with generator changeovers on the AC side, remember the DC array still needs its own isolation. Mixing problems — wrong breaker family — show up months later as welded contacts or mysterious burns, not always on day one.
Sourcing AC and DC breakers in Lahore
Tell GlobalPlus whether you need AC final/distribution MCBs or DC PV string/combiner protection, with voltage and amp targets. Contractors installing multiple rooftop jobs should standardise SKUs to cut mis-picks in the van. Dealers can inquire wholesale carton quantities on WhatsApp.
Bring cable needs into the same chat (PVC insulated cable for AC boards; ask which DC/solar cable options are available for the job). Visits are appointment-only. Pricing is on inquiry — solar seasons move stock quickly, so confirm availability before promising a client a weekend install.
Never paint over or ignore DC warning labels for aesthetics; service electricians need them years later.
Frequently asked questions
- Can I use an AC MCB if my solar voltage is “only 100 V DC”?
- Do not assume so. Use a device rated and marked for the DC voltage/current. Ask your solar electrician and confirm the SKU with GlobalPlus before purchase.
- Do I still need AC MCBs after the inverter?
- Yes — the AC distribution side still needs correct AC overcurrent protection. DC devices protect the DC array side; they do not replace house/shop AC breakers.
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Share string voltage/current and board photo on WhatsApp — GlobalPlus can point to DC vs AC breaker families.
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