• A dedicated battery room;
• A battery enclosure; and
  
• An area accessible only to authorised personnel

Note: Battery accommodation should be able to be securely fastened (locked) when not in use by authorised personnel.

Battery Room Requirements
The battery room shall be located so that access to a battery is not obstructed by the structure of the building or by the fixtures within the building.

• Be located outside the battery room; or
• Have no exposed live parts.

The most common practice in battery rooms is to use battery stands or racks. Some typical battery stands with vertically mounted cells are represented in Figure 1.

Figure 1: Typical battery stands with vertically mounted cells

Battery cubicle requirements
The battery cubicle shall be located so that access to a battery is not obstructed by the structure of the building or by the fixtures within the building.

If a battery cubicle is designed to house a battery and charger or other equipment (power supplies), a separate compartment must be supplied for the battery. If more than one battery is installed in a cubicle, each battery shall be installed in a separate compartment.

Note: A battery with two or more strings in parallel is considered one battery if it is supplying only one load.

Battery compartment circuits

Only circuits associated with a battery, (ie take-off cables or battery monitoring cables) shall be installed within the battery compartment of a cubicle. AC Input or Load Distribution cables are not permitted within a battery compartment.

Ventilation

Under conditions of overcharge or electrical abuse, significant amounts of hydrogen gas can be generated and emitted from VRLA batteries. It is therefore necessary to ensure there is adequate ventilation provided in battery room/cubicles. The minimum ventilation rate necessary to maintain hydrogen concentration to an acceptable level can be calculated using the following equation:

qv = 0.006nI where

qv = the minimum exhaust ventilation rate, in litres per second
n = the number of battery cells
I = the charging rate, in amperes (see below)

If there is more than one battery in a battery room then the total exhaust ventilation rate is the sum of the rates of all the batteries.

Charging Rate
Determined for two conditions as follows:

Condition 1 - If the charger does not have an overvoltage cut-out facility, the charging current is the maximum output rating of the charger or the rating of the output fuse or circuit breaker of the charger.

Condition 2 - If the charger has an overvoltage cut-out facility set to the appropriate level the charging rate is 0.5A for 100Ah at the 3 hour rate of discharge of battery capacity.

Ventilation Method

Where possible natural ventilation should be used for battery rooms and cubicles because of the fault potential of mechanical ventilation.

If natural ventilation is used, the minimum size of the inlet and outlet apertures is determined from the following equation:

A = 100 qv where

A = the minimum area of the apertures, in square centimetres
qv = the minimum exhaust ventilation rate, in litres per second

Arrangement of Ventilation
Exhaust air shall not pass over other equipment.

Ventilation inlets should be at a low level in the battery accommodation. Inlets should be positioned no higher than the tops of the battery cells.

Ventilation outlets should be at the highest level in the battery accommodation.

To ensure that airflow does not bypass the battery, inlet and outlet ventilation should be located on opposite sides of the room or cubicle.

Clearances

Battery Stand/Rack Requirements

Aisle width - The minimum aisle width on sides requiring access for maintenance shall be 900mm.

Single/double row, Single tier - In addition to the minimum aisle width, there shall be a minimum of 25mm clearance between a cell and any wall or structure on a side not requiring access for maintenance.

Tiered Batteries - If the battery has its cells mounted vertically, the minimum vertical clearance between any part of a cell and any part of the tier above shall be half the distance to the rearmost terminal or 75mm, whichever is the greater. The vertical clearance need not exceed 200mm.
If the battery has its cells mounted horizontally, there shall be a clearance between any part of a cell and any part of the tier above. This clearance should be in accordance with battery manufacturer's specifications or, if unspecified, shall be 50mm.

Figure 2: Examples of tiered battery stands.

Battery Cubicle Requirements

Conductor Size and Connections

Conductor size
When selecting suitable conductor size for a battery installation, three things must be considered,

Usually, selecting a cable capable of supporting the prospective short circuit current of the installation for at least one second allows ample current carrying capacity for the load.

Fault current rated cable must be maintained throughout the battery installation (including inter-cell connections), until the battery protective device. Ensure the cable size on the equipment side of the battery protection is of suitable size to support the load and rating of the protective device (fault current can now be disregarded).

Connections

Types of Switchgears