Low Bay Lights Bulb Size
Hello, I bought some 400watt Metal Halide Low Bay Fixtures and wonder what other wattage bulbs I can use. Can I place 250watt Bulbs in these fixtues. I asked the guy who I bought them from and I'm not sure he was educated on the subject.
I'm not sure if you'll get the exact answers you'll need here, but it's a great place to find any bulb you could ever possibly need:
Unforetally those type of lowbay luminaires they are very ballast specifed and bulb type.
you can NOT use the 250 W Metal Halide in 400 w Metal Halide ballast system the reason why is that because the ballast is designed to limited the current on the HID's.
and there are quite few diffrent type of 400 W MH's some are horzontal burning setting and some are base up only and some are open lamp rated
note : please check the lamp ordation [ postion ] which way the base is
Most lowbays useally are base up so it should not have some issue with it but i know 2 or 3 type of Lowbay they have the bulb cantered at 45° angle
if you want to change from 400 w to 250 W there is two choice change ballast / bulb or get diffrent luminaire.
The other thing is that they can load up the lighting circuit pretty good each one will draw about 4 amp [ at 120 v ] if you have more than 2 in the shop the max is 4 - 400 W MH on 20 amp circuit basied on contouis load but if you have other luminaires on that circuit you may have to reduce prorated depending on what it on it.
also when you turn them on expect the Luminaire take up to 5 min to fully warm up and when you turn off and turn it back on it will take about 5-20 min to come back on., so keep a flourscent luminaire on that circuit as well because most HID dont like " short " starting
at last but FINAL warning just about all the HID's they useally wire for multi voltage as well so i strongly advise check the voltage connection at the termatal block or junction box at the luminaire.
they will useally wired one of the 4 voltage depending on the type some are single voltage ballast type also
that why i advise check the voltage as well
the multi tap ballast will have 120,208,240 and 277 volts it will be pretty well marked on the ballast lead[s]
the single voltage ballast you will see it will mark for that voltage only
if this will be used in the resdental garage if so please hook up at 120 v only [ the code is pretty strict on this ]
Thanks Frenchelectrican, I have the information on the internal wiring. They are 120/480 (277) on the supply side and understand the taps on the xformer.
I hear you, but it is not getting through. Can you explain the relationship between the ballast and the bulb? I was looking at the bulb current draw difference between a 400watt and a 250watt (2.xamp and 3.xamp) and I don't understand the balance between the ballast and the bulb.:)
This is kinda compated detail how it works but both HID and Flourscents are work simuair manners with this set up
each ballast is designed for specifc type of HID or Flourscent even LED do use it but they are potically termed is " driver "
they are designed as how much current it can run thru the spefic wattage lamp by the amp, voltage ,.
i will give you a quick example on M-59 Ballast the M mean metal halide the 59 is the ANSI or NEMA number for the run of mill 400 watt Metal halide bulb.
the M-59 is rated at 400 watts at the correct voltage.
and also act like transformer to change voltage if necesarry if diffrent than what the spec called for.
really the MOST impoart part is make sure you have the correct ballst - bulb combo.
that is the same rules go with flourscent bulbs as well there is no differnce why but many manufacter specifed that way.
IIRC the M-56 is 250 w MH and electricaly both are not the same.
you can not run the 250 w MH bulb in the 400 W MH ballast because what will happend is the current will be too high for this bulb to take it and some case but it is true the bulb can exploded by too much current. and shorten the bulb life very fast too.
I know there is a ballast or two have dual wattage ballast [ not too common ] but it in the market but not many will take this unless a strictally replacement item that about it.
Thanks for the explaination French, Keith
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