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#18445 - 12/10/02 01:09 AM fuse selection for HID lights  
JohnnyB  Offline
Joined: Feb 2002
Posts: 33
Chicago IL USA
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

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#18446 - 12/10/02 02:14 AM Re: fuse selection for HID lights  
Trumpy  Offline

Joined: Jul 2002
Posts: 8,217
SI,New Zealand
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!.

Let's face it, these days if you're not young, you're old - Red Green grin

#18447 - 12/10/02 03:12 PM Re: fuse selection for HID lights  
j a harrison  Offline
Joined: May 2002
Posts: 106
southampton, england
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.

John H

#18448 - 12/10/02 03:57 PM Re: fuse selection for HID lights  
resqcapt19  Offline
Joined: Nov 2000
Posts: 2,148
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.


#18449 - 12/10/02 09:31 PM Re: fuse selection for HID lights  
HotLine1  Offline

Joined: Apr 2002
Posts: 6,853
Brick, NJ USA
For what it's worth..
400 watt, 277 volt, Advance ballast specs are:
Operating amps; 1.7 Input watts, 454

400 watt Lumark Hi-bay...
Starting Amps....1.40
Operating Amps....1.70

Based on the above, I would fuse at 3 amps maximum, midget fuse, 480 or 600 volt.
There are fractional amperage fuses available (2.25; 2.50) but they are pricey..

PS: Don, the sources for the above info are Advance Catalog, and WWGrainger catalog...
Another good source is Venture Lighting, they must have a web site.


[This message has been edited by HotLine1 (edited 12-10-2002).]


#18450 - 12/11/02 12:10 AM Re: fuse selection for HID lights  
JohnnyB  Offline
Joined: Feb 2002
Posts: 33
Chicago IL USA
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).]

#18451 - 12/11/02 03:23 PM Re: fuse selection for HID lights  
j a harrison  Offline
Joined: May 2002
Posts: 106
southampton, england
lokking at the way this circuit is wired, i personnally would rewire both sets back to the distribution point (if the client want to bear the cost),

I have spoken to on of my work mates and he suggests that the above is the best way to do things and also you say you are changing the control gear (ballast) within the fittings,

this is a good idea, but you still havent let us know what type of HID the fittings are.

Having the lot drawing 50 amps is high, very high.
I wish i was closer as i would like to see the installation for myself.

keep us posted as to what happens.

John H

#18452 - 12/11/02 08:16 PM Re: fuse selection for HID lights  
Wirenuttt  Offline
Joined: Nov 2002
Posts: 267
Am I reading you right, you have one neutral tieing 16 HID fixtures back to the panel and 2 hot coductors going back. So you're sharing a nuetral?

#18453 - 12/12/02 01:24 AM Re: fuse selection for HID lights  
JohnnyB  Offline
Joined: Feb 2002
Posts: 33
Chicago IL USA
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#!.

#18454 - 12/12/02 02:37 PM Re: fuse selection for HID lights  
j a harrison  Offline
Joined: May 2002
Posts: 106
southampton, england
I think that you should run the neutrals back one at a time, you should not share a neutral between the fittings,

i gather these lamps are Metal Halide with integral ignitors ??

i have never come accross this fault before but i am waiting to find our why.

Wirenuts do sometimes come loose as these fittings will vibrate a little depending on how secure to control gear is within the fitting and the fittings to the position they are mounted.

keep us in touch with the progress.

John H

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