China Emergency Light Discussion: Suitable for lighting complex facility control requirements, such as theaters, all lighting can be from normal powered lighting panels and controlled as a system during normal building operations. To meet the code requirements, the branch circuit must be automatically switched to the normal power of the emergency power supply during the loss. The emergency transfer device listed in UL 1008 is installed on the circuit to designate a normal/emergency situation to properly switch power between power supplies. This transfer function, which involves switching hot and neutral conductors, is complicated. The transfer switch must be designed to withstand the available fault currents and provide specific switching delays to prevent normal and emergency power interconnections. This type of transfer device is expensive to use on the branch circuit. Another option in some places is to install separate normal and emergency lighting circuits with parallel control. However, in the case of an emergency, control must be lost if it is automatically bypassed to ensure that this emergency lighting comes as required. This can usually be done using UL's 924 listed automatic load control relay (ALCR) shunt controller around the power supply when the power fails. Unlike the UL 1008 transmission options discussed earlier, ALCR does not have the power to switch between normal and emergency - a key difference. The UL 924ALCR monitors the normal power and switches the thermal conductors of the emergency line as needed around the control unit. In the case of dimmers it is usually the best solution because ALCR is much less expensive than a transfer switch. There are several disadvantages to using an application that is not dimming control, and the poor choice of installing controls from the beginning is on the emergency circuit. This method

　　
Not only does it require the installation of a shunt (or bypass) device, it is also a separate set of controls, which adds cost and project complexity. A better solution when using the toggle control is to install only the normal lighting circuitry of the control and use the UL924-listed automatic load control relay which causes the emergency lighting to follow normal lighting conditions except in the event of a power outage. Many people have the ability to receive switching signal control devices from the line in addition to the new generation UL 924 ALCR.

　　
The normal power cord before the device is suitable for this application.

　　
In this case, when the normal power occurs, switching the emergency light on the control unit ALCR feeds or shuts down the device in parallel with the controller. However, when the power supply is normal, the control device loses the ALCR for any reason to force the emergency light to turn on regardless of the on/off status of the control. This allows building owners and designers to use their normal utility control devices, such as time control

　　
Relays and occupancy sensors, while complying with code requirements for emergency lighting circuits. By perception

　　
This is a normal power solution at the branch circuit level that also ensures that emergency lighting fails in response to all power supplies, either locally or throughout the city.

　　
Energy saving

　　
In the past, power consumption for always-on emergency lighting was considered negligible. This attitude is

　　
It changes with the change of emergency lighting. The percentage of building lighting is higher loaded. Most current codes allow lighting office buildings to consume 1.2 watts per square foot. Newer code will reduce this by allowing 0.9 watts per square foot. Furthermore, it is explained and changed that emergency lighting specifications require a minimum (non-average) level of illumination meaning that emergency lighting may require more watts per square foot.

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