Article 690 NEC covers installation and safety requirements for PVs (PV). It defines components such as matrices, stereotypes, marshes, and separation issues, and puts how the circles should be protected, protect, registered and their subject. The article applies to both independent and interactive systems, with or without energy storage. It does not apply to widely covered power power plants under other NEC provisions, such as Article 705.
Unlike other electrical systems, Article 690 addresses unique conditions for photovoltaic systems, such as high voltage in cold weather, continuous background of sunlight, and rapid closure.
Below is a summary of the main points in Article 690: NEC:
Domain and applications
It applies to photovoltaic solar systems, including matrices, transformers, charging and energy storage units.
It covers both independent systems and interactive systems of facilities.
Facilities factories are widely excluded and controlled under Article 705.
Circle requirements
Voltage accounts
NEC requires that PV voltage depends on the lowest surrounding temperature because the solar units produce their highest effort in cold weather, and the equipment must be classified for this worst condition. The cold weather increases the open voltage of the circuits (VOC).
NEC Table 690.7 gives correction factors for crystal silicone units because they generate a high voltage in the same conditions. Example: If the lowest expected temperature is -10 ° C, hit VOC by 1.14 to determine the maximum circle voltage.
This corrected effort is used for the size of cables and other equipment so that the equipment classifications are not exceeded in winter conditions.
Current accounts
NEC requires the photovoltaic currents to be based on the short circuit current of the unit (ISC) x 125 %.
After that, the connectors should be 125 % of this current again (because the photovoltaic circuits are ongoing loads).
The result is 156 % double:
Excess current and protection
The photovoltaic, output and reflector source circles require excessive protection at 125 % of the maximum current.
Arch protection-beans Required for photovoltaic circuits that operate at 80 volts or higher.
The protection of the infected circle grounds should be isolated and provide an indicator.
Separation of the means and the rapid closure
The photovoltaic systems must have an easily accessible separation near the entry point.
The system cannot have more than six plots.
Rapid closure on buildings: Controlled conductors must decrease to 30 volts or less within 10 seconds for firefighters safety.
Introduction and interconnection
PV systems can be based or not available, but the equipment foundations are mandatory in all cases.
Mineral unit tires, shelves and attachments should be linked to maintaining continuity and electrical safety.
Signs and put signs
The photovoltaic units must be marked VOC, ISC, Max System Voltage, and Max Power Ratses.
Race covers, intersection boxes, and clouds boxes should be placed: “Warning: PV power source.”
Buildings with photovoltaic systems must include evidence that shows all separation sites Rapid closure Poles.
Wires Roads (690.31)
All wire methods can be used in the race race and the NEC wires in the PV sects if it is specially inserted for photo use.
Since PV units often reach 70-90 ° C or higher in direct sunlight, conductors must be inserted to wet sites and have a temperature classification of at least 90 ° C, although 105 ° C and 150 ° C are also common.
NEC requires sufficient length of the cable to allow a safe replacement of the integrated packaging devices.
Types of permitted wires
NEC allows PV WIRE, USE-2 Cable, MC (MC-Clad), Cable and RaceWays For photovoltaic and directing source circuits.
When to use each:
PV wires It is used in the open air for stereotypes and the wires of the cliff.
Cable use 2 It is a common option for direct burial and outdoor running in portable systems on the ground. It is ultraviolet resistant and moisture, but it is less elastic than photovoltaic wires.
Tc-ac cable (The stairs cable-it can be used outdoors in the outdoor air in the photovoltaic output circuits of the separatist feedback, provided that the installation is in non-accessible locations and the cable is secured at intervals that do not exceed 6 feet.
MC cable It is usually used inside buildings or ceiling breakthroughs, as NEC requires metal protection for photovoltaic connectors at home.
Racing race (channel) It is used for the longest operation inside the buildings or between the equipment. He presents The highest mechanical protection and compliance with the requirements of NEC to contain minerals inside. Racing wages are required when photovoltaic conductors enter into a building or accessible locations where material protection is necessary. However, it is not required for outdoor wires if the PV or US-2 clock is used and properly supported.
Outdoor sects
A mono -connected PV wire is allowed for communications between stereotypes in the wand.
PV wires are allowed to use -2 and PV in the open external sites of PV source circles.
Cable trays can be used if the PV wire is supported at no more than 12 inches and secured at intervals not exceeding 4.5 feet.
This wire should be resistant to sunlight, moisture resistance, and classifying it for at least 90 ° C.
It may be installed in cable trays or open races, but must be supported and secured at required time periods.
Inside the buildings
Once the photovoltaic source circles penetrate or out the building, the NEC requires that it be in the metal racing fare, MC cable, or packages until the first accessible semester.
If a flexible metal channel (FMC <¾ in) or the small MC cable (<1 in) is used via the tributaries, it should be protected by guard strips.
The compact conductors in the roofing materials should be placed for continuous exposure to sunlight and weather.
Flexible ropes
It is only allowed to track the photovoltaic lines that move to follow the sun.
These ropes should be a solid service, an unfair use, and resistant to sunlight and water.
Small conductor cables
Signs
All racing devices, cable trays, link boxes, clouds boxes, and attachments that contain photovoltaic connectors:
“Warning: PV power source.”
The stickers should be reflective, permanent, a red background with a white text, 10 feet diverge.
Storage batteries
Article 480 applies first: All batteries must meet the general NEC requirements for installation, ventilation, excessive protection and access to maintenance.
690 additional provisions:
In housing, battery systems should work at 50 volts or less, unless they are guarded.
Record means of chains are needed for more than 24 cells (48 volts nominal) to allow safe service.
The current specific devices (such as valves) should be installed near the batteries to protect against short circle errors.
Battery containers and shelves should be prevented from accidental contact and are made of unspecified or guarded materials properly.
In NNC, you can shop for PV wiresand USE-2and MC cableand Tc-aer, The conductors, and Battery cables That meets Nec 690 requirements for safe solar compositions compatible with the symbol.
