400 watt HPS Electricial Question

I'm building my own 400 watt HPS light
I bought a kit to build it.
I'd like to put a fuse in it, but I have no idea what size
anyone know any good links or can tell me what size fuse to put in it.?
Thanks

You want it a little beefier than the amps the light pulls but not a whole lot more. I'm not a sparktrician so I don't know the exact number.

LoL me either.
I had industrial electricity in college
but I didn't pay much attention. LoL
yah I was thinking about protecting the transformer
I know the socket can take 5000kv, but I'm pretty sure it's
low amps.
I was thinking about making it switchable, but I heard
some switches arcing across the contacts. I figured if
I fried the ignighter that would be it.

I majored in coeds and how to score good dope.

alright hang on let me do the math here

if you use a 4-5 amp fuse you should be good to go

as far as going into the Kv range i doubt it

the current would be very very very low... and after all its the current that does the work, not the voltage


if you want me to be more specific you could tell me how many turns are on the primary and the secondary of the transformer and i can do all the work for you

a 400 watt light uses a little less then 4 amps while running, a little more when starting up. try a 10 amp fuse.

awesome Thank You Very Much

desertrat said:

a 400 watt light uses a little less then 4 amps while running, a little more when starting up. try a 10 amp fuse.

Click to expand...

damn i forgot your right

when a light bulb is "cold" as in off.... it has a lot of resistance, therefore taking a lot more to spark it up (plus whenever you turn a switch on there is a large power spike this is why light bulbs only go out when you turn them on)

as it heats up it has less and less resistance, which is why a ballast is needed in the first place to prevent it from drawing additional current due to low resistance

the amp draw of a light should be watts divided by Voltage if I remember correctly. so just do a quick W/V=A I'm pretty sure.