I wired up my temporary box last weekend, and the light fired up ok with no problems.

Here is a pic. Click the thumbnail to see the full picture:




I have since moved the thing into the garage, and placed the ballast and wiring into the positions that I want it to be for the final project:




However when I fire up the light I see some arks in the ark chamber flashing around, but before the thing ignites the fuse blows. I'm not sure what I could have done wrong. I did take most of the wires and bundle them all together with electrical tape, but nothing was exposed. Could it be arcing somehow? Would a bad ground be a problem? I checked the ground, but it appeared ok.

I also noticed a black spot on my bulb, but I think that was already there:





In the lighted pick I was using a 10 amp 32v (it was in the 120v box bin, but the fuse says 32v). When it blew I replaced it with an 8 amp 250v fuse, but that blew as well. Is 8 amps enough?

Please let me know if you guys have any ideas.


[edit] I fixed the links.

Ballast Specifications
Ballast made for Lamp type: 400W Metal Halide
ANSI Designation: M59
Input Voltage: 120
Circuit Type: CWA
Watts Input: 458
Max Input Current: 4.00
Nom Open Circuit Voltage: 300
Fuse Rating: 10


PROBLEM 5— FUSES BLOW OR CIRCUIT BREAKERS OPEN ON LAMP START UP

POSSIBLE CAUSE
CORRECTIVE ACTION

1. Overloaded Circuit
Rewire to accommodate starting current of lamp/ballast combination.

2. High Momentary Transient Current
Can be caused by reactor or autotransformer ballasts which draw high initial currents. Use current protective devices incorporating time delay elements. If these fail, change ballast as its characteristics will affect lamp life.

Use a slow blowing fuse. It is set up for high currents for a longer period of time before blowing. 8amp is to small. Also use the correct voltage rating. 10amp 120 volt (check your ballast voltage) slow blowing fuse.

Your picture thumbnail link doesn't work. It just takes me to image shack.
Is that two starter coils i see to fire up your ballast. I thought you only needed one.
I think the bulb is to close to the ballast. (melt it maybe)
Make room for your reflector too.
Use a heat shield - usually aluminum flashing

Sorry forgot to mention.

Ballast 120 volt 60 HZ multi-tap, Pulse start ANSI code M135/M155 with Cap, and Ignitor.

Thanks for the info.

I've read that a 5-8 amp fuse should be used. I'll try your suggestion of a 10 amp, but I don't feel comfortable using anything higher. Both fuses that blew were slow blows.

Ones a cap the other is the ignitor.
Thanks for the advise on positioning the ballast. I'll move the ballast a little farther away.

Currently I'm just in my testing phase so I wasn't going to let it heat up to melt anything. I was simply testing the wiring to make sure it would light. I have a norpro cut and ready to put in, but this is simply a test box for me to get to try some things out.

That arc tube length is huge...that a Venture? If you're popping fuses so easily go back over the wiring one connection at a time and look for any signs (anywhere) of shorting.

Yep that's the venture. It's funny you mention the arc chamber. I thought it was rather large too, but I had nothing to compare it too (actually I was suprised by the bulb size overall). However I thought it was standard since on lighting unlimited they describe the bulb as this:

Venture Uni-Form Pulse start lamp, part number 40124. 400W/H75/ED28/PS. This lamp offers the Smaller arc chamber, Intintial Lumens of 40,000 100 lumens per watt, Mean Lumens 32,000, Avg. life 20,000 hr., Color temp 4000, warm up time 2-3 min, restrike 4-6 min, CRI 65.

If this bulb causes image issues due to this, I'll have to pick up another bulb.

I checked mogul connections, switch connections, and the ground at the socket. I'll go through and break up the big ball of tape tonight to check the rest.

I checked the wiring tonight and found that 2 of the unused input voltage wires were touching. I don't really see why this would be a problem, but I seperated them, and the fuse no longer blows when I fire up the ballast.

Thanks for your help guys.

Glad you found the short. Use wire nuts on the ends of the unused wires to keep them from shorting from now on. Electrical tape is not a good solution.

I remember when I was reading up on the Uniform lamps from Venture. They are supposed to have a smaller arc envelope and no nipple on them. Either they have changed the specs because they were having problems with it or you were sold the wrong lamp. If I could only remember where that PDF was...