lighting question before i do trial and error and get injured lol!!!

heres my question
ive got 2 400w ballasts i have 400w mh bulbs aswell as 400w hps bulbs
there is no marking other than power rating saying whether it is a mh or hps ballast. i screwed in a mh bulb and it has been working for a month.
a grow buddy from work says i can take the 400w hps bulb and use it in the same balast???? is this true or am i gonna get splinterd with red hot glass????

check out my baby at 16days veg from outdoor bagseed will update soon
https://www.rollitup.org/general-marijuana-growing/140247-indoor-400w-mh-1-seed.html

i have a switchable ballast, but you have to use a toggle switch to go from one to the other. i also have a digi ballast that automatically senses which bulb you're using. i've never heard of a coil ballast that auto-changed between the two. i'd take them in to your local grow shop and let them tell you. if you open the ballasts up, be very careful. they can hold residual electricity and will fry your ass.

ok so im pretty sure i have 2 mh ballasts and i know they are really old i found em in an old warhouse with a couple boxes of bulbs it was kinda a gold mine there were 10mh ballasts and 2 boxes of 400w bulbs one box had smaller 400w and one bigger 400watters plus enough 4'fluro bulbs and ballasts to turn the whole warehouse into a grow op............. now that i think of it maby i robbed someone elses grow lights...........

anyway basically i need a digi ballast or a switchable ballast thanks for the advice and one more question

is there a difference in lumen rating between the small 400w mh bulbs and the large 400w mh bulbs????

i'm not sure, but i believe the difference is the bigger bulbs are just older models. i once had a 1000 watter that was bigger than a football!

lol thank you vm for the advice. i was really nervous about pluging that hps bulb in ...... i was gunna get a heavy sweater and saftey goggles and helmet and everything to do a test run. actually i just had a thought if i did try the 400w hps in my 400w mh ballast would/could it damage the ballast??? im not gunna risk it.... thanks again

JFK

If they are older ballasts as you say, I would have to assume they are independent to their lamp types.

I really nice ballast I just purchased is a 600W Galaxy Digital(They also have 250,400 and 1000):

Heres a link for ya:
http://www.thegrowlight.com/600w-galaxy-digital-hps-mh-ballast.html

You can check the ballast and see if it has an igniter. That would indicate its a sodium ballast. if it is just the transformer and the capacitor it will not burn a sodium bulb.

also if you are burning a metal halide and the igniter is there you prolly need to take it out of the circuit when using a halide so you dont burn up the igniter.

so then basically with a 400w switchable ballast the switch controls the igniter then??? when you wanna run a mh bulb you switch the igniter off and when i sodium bulb is used you just flip the igniter on... im pretty confident that if my ballast has an igniter i could make my own switch for this purpose im gonna rip one of my ballasts apart tonight after work and take some pics so maby somone could identify the igniter or lack there of