wanderer
Member
- Location
- GA and NC but sometimes MI
- Occupation
- Master Electrician
I have been tasked to take voltage/amperage/wattage readings of various light fixtures on a lighting upgrade job. I was told to use the company's AEMC 8220 power quality meter with an MN-193 clamp. The meter and clamp were NIST certified within the last 6 months. I've checked multiple fluorescent and LED fixtures with it since the certification and everything seemed fine. I've used this meter before and it works well.
A couple of days ago, I was trying to get readings on 400w pulse start metal halide fixtures and nothing seemed to make sense. The wattage is was getting was around 300-340 watts input. I tried again today (after some advice from AEMC tech support) and ended up getting a reading of 1.6 amps and about 163 watts at 120 volts. To try to convince myself that something was wrong with the meter, I used a Fluke i400 plugged into a 3000 FC meter and pulled out my old Amprobe amp clamp and both showed 1.6 amps! I've double checked the settings on the clamp and meter and they seem to be correct.
I've verified that the lamp is a 400 watt pulse start and the ballast is a 400 watt ballast. Each reading was taken after the light was on for at least 15 minutes to warm up the lamp. Since we are removing the lights, I've been able to test several fixtures and get results well short of the roughly 460 watts we would expect to see.
I'm sure I'm missing something obvious, but I can't figure it out. The meter seems to work fine for fluorescent and LED loads, but seems to be grossly wrong on this metal halide. Either that or I've found a 400 watt rated fixture that only consumes 160 watts.
Thanks in advance for any input!
A couple of days ago, I was trying to get readings on 400w pulse start metal halide fixtures and nothing seemed to make sense. The wattage is was getting was around 300-340 watts input. I tried again today (after some advice from AEMC tech support) and ended up getting a reading of 1.6 amps and about 163 watts at 120 volts. To try to convince myself that something was wrong with the meter, I used a Fluke i400 plugged into a 3000 FC meter and pulled out my old Amprobe amp clamp and both showed 1.6 amps! I've double checked the settings on the clamp and meter and they seem to be correct.
I've verified that the lamp is a 400 watt pulse start and the ballast is a 400 watt ballast. Each reading was taken after the light was on for at least 15 minutes to warm up the lamp. Since we are removing the lights, I've been able to test several fixtures and get results well short of the roughly 460 watts we would expect to see.
I'm sure I'm missing something obvious, but I can't figure it out. The meter seems to work fine for fluorescent and LED loads, but seems to be grossly wrong on this metal halide. Either that or I've found a 400 watt rated fixture that only consumes 160 watts.
Thanks in advance for any input!