View Full Version : DANGEROUS low voltage wiring?!?! headache

10-04-2006, 10:42 PM
Hello, I am in somewhat of a frusterating situation. I have a 400 watt high pressure sodium light that has a 10 foot cable from the reflector/bulb to the balast. I purchased this on ebay and therefore this is not a factory manufactured or guaranteed item. It appears to function properly, but I noticed the wiring between the bulb and balast was some regular hardware store Carol 16/3 300v wire. I was alarmed at this Because after a little research I discovered 400 watt high presure sodium lights uses a 2300 volt arc to start the bulb. 2300 volts is MUCH more then 300, obviously way out of spec? So at a local electrical store the only wire I could find technically suitable was some 2500 volt rated test lead wire (17 or 18 gauge). This new wire works, yet it might be an illusion but it seems dimmer then before, I found that 400 watt hps lights use 100 volts once warmed up and runing- so this would mean 4 amps across the 20 feet (remember 2 leads) of 18 gauge wire. I quickly calculated the voltage drop and limit in the current because of the wires resistance to bring my wattage down about 5 or 6 watts . To add one more annoyance, I spotted a nice hps light (600 or 1000 watts comercially made) in a hydroponic store with simple 16 gauge 600 volt wire...

My question is, should I just run some bigger wire only rated for 600 volts as i spotted an instance were it seemed ok? or should I double up this high votage stuff or find some exotic large gauge high voltage wire to be technically rated( and guaranteed safe I dont want arcing and melting wires) at the high startup voltage (2300 volts)? of course otherwise, I could do nothing, and accept the 6 watt loss to wire as unimportant.

Thanks for any replies

10-07-2006, 11:31 AM

I can see your concern, when the ignitor fires the bulb it sends a high voltage pulse. All this does is ignite the bulb and it lasts for a brief moment after which the capacitor then maintains the ignited bulb. The correct cable that you will need for your lamp cord needs to be rated for 600v and 16 gauge in thickness. This cable is more than adequate.

Sunlight Supply
10-09-2006, 09:20 AM
Hello Happy Bug,
I am an employee of Sunlight Supply, and here is a quick answer to your concerns. The 300V 16g. 3 wire cord you have is suficient. Underwriters labatories (UL) approves that for the 400W HID fixtures. Even though the ballasts may spike up to 3000V at initial start up with nominal running is just over 100V. I would suggest keeping the old cord instead of going down to an 18g wire. We here at Sunlight Supply, use the 16g 3 wire 600V rated cords, this is rated for the 1500W and lower so it covers all the bases. The watt drop you noticed is probably due to either the thinner gauge wire or if you extended the lamp cord. Hope this is helpful.