Basic Electrical Installation Work

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After testing, the emergency system must carefully restored its normal operative state.5V. Figure 14. Negative connecting bar Positive connecting bar All plates deeply ribbed Negative plate Separator Positive plate FIGURE 14. The batteries contained within these units should replaced about every years, recommended the manufacturer. Self-contained units are suitable for small installations about 12 units. Secondary cells A secondary cell has the advantage being rechargeable.61 The construction lead-acid battery. When the cell connected load, the chemical energy converted electrical energy.Basic Electrical Installation Work 342 The British Standard recommends that the full load should carried by the emergency supply for least every months. Thus, supply can be provided connecting four cells series. . Definition A primary cell cannot recharged. may necessary produce the record evidence satisfactory compliance with statutory legislation to duly authorized person. Mercury primary cells have emf 1. Each cell delivers about 2V, and when six cells are connected series 12V battery formed the type used on motor vehicles. Once the active chemicals are exhausted, the cell must discarded. the cell is connected suitable electrical supply, electrical energy stored the plates the cell chemical energy. the cell con- nected suitable electrical sup- ply, electrical energy stored the plates the cell chemical energy. A lead-acid cell secondary cell.35V, and can have very large capacity small physical size. Once the active chemicals are exhausted, the cell must discarded. They have long shelf life and leakproof construction, and are used watches and hearing aids. Primary cells, the form Leclanche cells, are used extensively por- table power sources for radios and torches and have emf 1. Primary cells A primary cell cannot recharged. Larger voltages are achieved connecting cells series. A record should kept each item equipment and the date each test qualified responsible person. Definition A secondary cell has the advantage of being rechargeable.61 shows the construction lead-acid battery