I did a call on a 7-400 watt 277v metal arc HID lights that went out. Turns out one smoked and was pulling 50amps for 30 seconds or so before tripping. I find wire nuts laying in loose in boxes and the one that smoked. I take it out of the circuit and the lights work for an hour or so and then my partner is like "you smell something?" Sure, another one bit the dust, so I'm going back with a bunch of transformers and stuff, but I want to fuse the fixtures. They have a 1.7 amp rating, but they pull more than that on startup, right? Is the fuse selection like that of a motor? Size for inrush with a duel element fuse? They are all warehouse lights I got to do of a lift.3WYSAUFE1T
Johnny, My advice to you would be, check out the wiring first-off, secondly check that you have the right sized control gear. I assume that you are talking about Metal-Halide HID lighting?. If not, could you please advise as to what type of lighting gear you are using. With MH, the start current is the hardest part on the circuit wiring, we recently installed 48 250Watt lowbays in a shop, we had a multitude of problems. Need extra advice, just reply!.
Re: fuse selection for HID lights#18447 12/10/0202:12 PM12/10/0202:12 PM
We as a company install a lot of HID fittings High Pressure Sodium, Metal Halide, Mercury Vapour, and some low pressure Sodium for car parks,
The thing that puzzels me is the loading and the current draw you are saying, it sounds as though that the installation is incorrect as the approxiamte loading on 230v ac with a loading of 2800watts @ 12.17 amps.
You getting a reading of 50 amps is rather to high, my advice is that you check the following;
cable type, size, and integrity (damage etc) lamp type, control gear (ballast, ignitor,capacitor) wiring of control equipment integrity of CB (is it suitable for this type of load)
if these all match then check the supply loading,
I am curious to know the outcome so please keep me posted.
Re: fuse selection for HID lights#18448 12/10/0202:57 PM12/10/0202:57 PM
I thought that the starting current for most HID ballasts was less than the running current. I has been on all of the fixtures that I have installed in the last few years. Even with the lower starting current, the inrush is still high, but not as high as incandescent. Dual element fuses are often installed at about 150% of ballast load to prevent the circut breaker from trippin when there is a ballast failure. Don
Re: fuse selection for HID lights#18449 12/10/0208:31 PM12/10/0208:31 PM
The way it’s wired are two rows of lights hanging in the web joists in a warehouse? Two 20amp single pole breakers supplying 277 two each row. 8 lights in two rows. One hot lead to each row and the neutral leads to each row are tied to one neutral back to the panel. I don't have the specs of the fixtures in front of me to post, but I think my replacement transformers are coming in tomorrow and I may be on the job by thurs or fri. I will be the guy on the lift and lowering to another guy who will be ripping them apart and changing ballasts and stuff. When I took the fixture that smoked originally out of the circuit and got all the other lights to work I measured approximately the correct amp draw per string; 1.7 amps per fixture, and then I started to work on a hanging heater for a hour or so then another one smoked. I'm thinking that the guy who operates the warehouse kept resetting the breaker and watched the lights hum and go out; all the while it was pulling 50 amps through the primaries on these lights??
The wire gauge appers to be sized correctly. The neutral must be sized to the total amp of both circuts,right? The thing is I am asuming everthing worked before as it was designed so I haven't, as yet, double chected wire size and run and all that.
Would a loose wire nut cause adverse condition for premature failure of a fixture? On electrical motors their is a +or-/min and max voltage rating. I didn’t see one on the fixture, I'm wondering if this first fixture blew from high volts.
[This message has been edited by JohnnyB (edited 12-10-2002).]
Re: fuse selection for HID lights#18451 12/11/0202:23 PM12/11/0202:23 PM
Sorry, 8 total fixtures...two rows of 4 fixtures each with the two hot legs and one shared neutral back to panel. The transformers are kits multi tap with a cap. Like 120/208/240/277 with a capacitor in series with the lamp, no igniter. The same as what was in the fixtures 400watt M59. I started to change them out today, haven’t found anything conclusive as yet, although, I swear I keep finding loose wire nuts without evidence of direct short to the box. Like,.. I go to take a box cover off and a wire nut falls out. What the fu#!.
Re: fuse selection for HID lights#18454 12/12/0201:37 PM12/12/0201:37 PM