Frequently Asked Questions

Why use electronic ballasts?  

Electronic ballasts, when used with fluorescent lamps save significant amounts of energy, up to 30% in some instances.  Also electronic ballasts will provide flicker free illumination, enhance lamp life and weigh less than their conventional equivalents.

Why use electronic ballasts for High Intensity Discharge ballasts?    

Although the energy savings are smaller for HID electronic ballasts compared to fluorescent, there are still savings to be had.  Square wave lamp current provides flicker free lighting and constant lamp power regulation helps to increase lamp life and maintains constant colour appearance.  Lamp condition monitoring is also a facility available in Leafnut enabled ballasts, especially useful in streetlighting installations.

How far can Harvard ballasts be mounted away from the lamp? 

HID ballasts can be mounted up to 25m away as standard, 100m to special order.  Fluorescent ballasts 3m and combined HF/emergency ballasts 1.5m.

What is the maximum distance I can mount a Harvard HID ballast?

Harvard HID ballasts employ a unique lamp striking method which allow the lamps to be mounted further away from the ballast than with conventional gear. If you use the specified cable types below you will be able to achieve reliable starting at these maximum distances.

Cable specification for long lamp leads must be LOW Smoke Zero Halogen Cable ref 318*B.  Telephone Harvard technical department for further information.

If luminaire needs to be earthed then for maximum striking distances earth it locally at the lamp end, do not feed the earth back through the ballast.

How many Harvard ballasts can I put on a circuit breaker, and what type of circuit breaker do you recommend?

All Harvard IDD Range HID ballasts have inrush current suppression and we recommend type C breakers as used for inductive loads. The maximum number of ballasts can be calculated from the following formula:
(2 x nominal ballast running current) / circuit breaker rating.
For other ballasts please contact Harvard Techincal dept for details.