400W MH lights, input current?

[eeinpa]

Greetings
My employer has buildings with Lithonia 400W metal halide lowbay lights connected in banks on 240V 3ph. While the nameplates say current at 240V is 2.0A, we seem to see more than that... enough that breakers are sometimes tripping even when (by calculation) loaded at no more than the NEC 80% permitted for continuous operation.

Any opinions on whether the current specs on these ballasts accurate and applicable over reasonable ranges of temperature, lamp age, etc.? We actually seem to be having more troubles in cold weather (our buildings are not particularly warm this time of year) than in hot.

What's the HID load look like? Does it have a high peak current which may cause excessive IR heating, and if so, why don't the lighting companies mention that anywhere?

Thank you for any useful suggestions!

 

[rbulsara]

1. Ask the mfr. of the HID lights or check the catalogs for inrush currents, if the breakers trip only when turning the lights on. If the breaker trips sometime after the lights are already on for a while then look for other reasons as below.

2. Excessive Harmonics may be a reason which will trip a regular thermal magnetic MCCB at lower "rms" currents.

3. Make sure not circuit breakers are not GFCI type, that will definitely cause nuisance tripping on HID lights.

4. There may be an actual intermittent fault occurring on the circuit. Moisture etc. may be an issue

 

[itsmoked]

Have you clamped a true RMS ammeter on a few?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[EEJaime]

You are running 3-phase ballasts? From your numbers, 400W at 240V, (assuming a 20% +/- ballast loss), would give you the 2.0 Amps, but at 240V 1-ph. Are these multiple single phase ballasts alternating on 3 phase circuits?