Equipment clearances and safe working space

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All electrical components must follow proper requirements for clearances (space between one component and another object) given by manufacturers and by electrical codes. Requirements for clearances fall into two categories: clearances for ventilation and clearances to create a safe working environment. Often times the clearance requirements that a manufacturer makes in a product manual will be more stringent than the requirements outlined in an electrical code - the larger of the two requirements should be followed. In any case, it is important to use proper judgement when performing an installation. Equipment should be placed in a location that easy to access, provides proper ventilation, is clear of other objects (not used for storage), provides sufficient space in which to work, and is easy to exit in the case of emergency. Equipment should be installed in a height and location that is appropriate for the space and users.

Clearances for ventilation

All components used in off-grid PV systems generate heat when operating because they are not 100% efficient. The rated output or performanec for a given component will always be measured at a specific temperature and temperatures in excess of that value will lead to reduced performance (lead acid batteries will temporarily have improved performance, but their cycle life will be shortened in compensation). This means that cooling, especially in warm climates, is very important and must be carefully considered to ensure that a system performs properly. If a particular component has clearance requirements they will be outlined in the manual or installation guide. Inverters and charge controllers will have specific required clearances, PV modules often do not give guidance, but there are guidelines available in the mounting systems page.

  • Example of manufacturer specified clearances on all sides.

Safe working space

It is necessary to provide adequate space between any equipment that must be accessed for service or that have operable parts and other objects (including other system components and parts of a building like a wall) to enable anyone working on the system to do so safely and to permit access/exit in case of an emergency. Clearances for a safe working environment will be outlined in a country's electrical code. In any case, it is important to use judgement during an installation. Equipment should not be installed in spaces that are used for storage or that do not permit easy access/exit. Below are some example minimum clearances from the US National Electrical Code, which sensibly designed to take into account the space that a person would need to safely work taking into account shoulder width, reach etc.

  • Recommended minimum clearance for space in front of a component and a wall.

  • Recommended side to side clearance. The 762mm can include the width of the component.

  • If two components are located above and below one another. One should not extend more than 152mm beyond the other.

  • Any component with a door must be located such that its door can open at least 90°.

  • Any component The maximum height for any serviceable equipment or operable equipment (like a breaker or disconnect) is 2m.

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