Author Topic: 1 lamp striplight: Running romex wire past the ballast & heat concerns doing so  (Read 240 times)
Lightingguy1994
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1 lamp striplight: Running romex wire past the ballast & heat concerns doing so « on: November 11, 2017, 11:46:11 AM » Author: Lightingguy1994
Greetings, as some of you know I have a bunch of Sylvania single lamp strips that I converted into 3 lamp but I plan to just have them 2 lamp side strip with a typical HPF rapid start.

My issue is when a full size magnetic ballast is installed, there isn't much space around it to run a wire past it to go to the next fixture for a row mount. For that to work, the wire needs to run right beside the ballast to get past it to get to the next fixture. I have concern that the heat from the ballast would pose a problem for the wire, I am wondering if any of you had experience or know more about romex wire and its heat tolerance. Is it safe to run it near a hot ballast ? Hot as in if it was running all day typical use hot. Basically just want to know how the long term would be. Worst case is I use slimmer electronic gear and T8 lamps.

I'm not setting anything up currently but I do plan to do so in the future. The fixtures will be pendant mounted with a home made kit I have designed. More on that in time.

 
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Ash
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Re: 1 lamp striplight: Running romex wire past the ballast & heat concerns doing so « Reply #1 on: November 11, 2017, 12:17:49 PM » Author: Ash
Over here ballasts have a temperature rise rating :



In this example the rating means 60 deg over ambient for normal work conditions, 170 deg over ambient for stuck starter conditions. (in the ballast on the picture there are also 70/185 ratings respectively present, measured according to a different test procedure)

For ~30 deg ambient inside the luminaire ballast channel, the working temp then is about 30 + 60 = 90 degC. So, a 90 deg rated wire would be the minimum required to pass near the ballast. If you also insert Glass braid over the cable (so it does not touch the ballast directly) you add some more safety margin

Thats about it. Though i dont know what are typical ratings for US ballasts
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sol
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Re: 1 lamp striplight: Running romex wire past the ballast & heat concerns doing so « Reply #2 on: November 11, 2017, 12:45:45 PM » Author: sol
If you're worried, you could always run some TGGT wire, the same kind used to wire the inside of typical kitchen ranges. They have fibreglass insulation instead of polymer. Or like Ash suggested, fibreglass sleeves would work as well.

Otherwise, if they are pendant, you could run a separate wire down to each strip, but that would make the wiring more complicated on the ceiling.
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Lodge
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Re: 1 lamp striplight: Running romex wire past the ballast & heat concerns doing so « Reply #3 on: November 11, 2017, 02:00:11 PM » Author: Lodge
If you're worried, you could always run some TGGT wire, the same kind used to wire the inside of typical kitchen ranges. They have fibreglass insulation instead of polymer. Or like Ash suggested, fibreglass sleeves would work as well.

Otherwise, if they are pendant, you could run a separate wire down to each strip, but that would make the wiring more complicated on the ceiling.

If they are pendant you could also install plugs on the ceiling and just plug each light in, this is actually common in large buildings like warehouses, and if a fixture fails it also makes for a quick change out of the entire fixture they are plug and play, in a building like Costco I can change a fixture in less time then the lift takes to get to the fixture...
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Lightingguy1994
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Re: 1 lamp striplight: Running romex wire past the ballast & heat concerns doing so « Reply #4 on: November 11, 2017, 02:15:19 PM » Author: Lightingguy1994
Those are good ideas! Never thought about the plug in one. My fixtures will likely be attached to each other as a row so removal of one is not possible.

I know most romex is rated 90 degrees but how hot does a typical ballast get after like 8hr of running ? I thought about the kind of rome with the armour but that wont fit in the gap between the wall of the channel and the ballast. Instead i may use armoured romex on the tops of the fixtures since they are pendant, but I have plenty of time to figure it all out, just needed input
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Re: 1 lamp striplight: Running romex wire past the ballast & heat concerns doing so « Reply #5 on: November 11, 2017, 03:22:57 PM » Author: Lodge
The ballast shouldn't get to 90C unless something is wrong, it should sit around 50C or lower so they are warm to touch but it won't burn you, If you are running them in rows you could also use something like XLPE wire which carries a 90C continuous rating and a 140C emergency rating and a 250 conductor short rating, and is nice in trays so they will survive just about anything the ballast might throw at them, and allow the ballast to burn itself out without a fault and cost per foot is about the same as romex maybe a few cents more, if your going to run it down the light trays don't forget to use chase nipples so you don't nick the wire while pulling it.. But plugs are nice and you can also change the fixture styles without much work as well, plus if your not around just about anyone change it out so long as you tell them where the spare fixture with plug already wired to it is located, and in a commercial setting you don't need to be a sparky to change a plugged in fixture but you do if the it's hardwired, and murphys law will always cause the first fixture in the row to fail so you also have to power down the entire row which never happens with individually plugged lights.. 
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Re: 1 lamp striplight: Running romex wire past the ballast & heat concerns doing so « Reply #6 on: November 13, 2017, 03:08:54 AM » Author: Medved
The ballast shouldn't get to 90C unless something is wrong 

With many ballasts you are wrong:
Most European ballasts are rated to run up to 130degC (include the depicted one; that has temperature rise of 50degC, so with 80degC inside of the fixture, the ballast operates at the rated 130degC), it is then the matter of the fixture thermal design, how far it may go. And many fixture designs really count on such high temperature - then the wiring rating and placement within the fixture should correspond to that as well. That is very dangerous, when during repair you don't follow the designed wiring layout and rating (well, I don't say all the fixtures are wired correctly even when new from factory...)

Of course, it means the ballast lifetime then shrinks to few 10k's hours and have limited fault margin, but the offered fixture is then compact, sealed and cheap...
And that is not that much problem of the new designs (these are usually well engineered to be below the formal safe limit, as that is the cheapest way today), but mainly many older fixtures are prone to really running hot, when e.g. mounted on something fluffy (glass fiber fire insulating panels used e.g. on wood surfaces,...)
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Re: 1 lamp striplight: Running romex wire past the ballast & heat concerns doing so « Reply #7 on: November 13, 2017, 04:52:45 AM » Author: Lodge
Medved, The above ballast is not overly common in north america which is where the original poster is located, so they will normally be using an F-Can styled ballast with a sand and tar filling and if an F-can ballast gets to 90C the automatic thermal protector, which will be built in unless its an ancient ballast, will kick in causing the light to cycle until the ballast cools, so during normal operation it shouldn't ever hit 90C, Mainly I want to steer them away from using Romex, which while it carries a 90C rating its only rated to 60C continuous so it will take a higher temperatures for a while but over the years it will fail where XLPE won't.  Even running Romex at 60C all the time will cause it to discolor and go brittle, and while TGGT will work it's rating is way beyond what it will ever see just like MGT (450F) or Flame1000 (2400F) and they cost a lot more then ROMEX or XLPE and normally it's not in the big box hardware stores either so they have to go hunting for it..

But you are correct the above ballast will allow itself to get hot enough for the insulation to fail and then they will smoke and maybe catch on fire, but generally a small florescent ballast won't normally get to hot to hold in your hand even after extended operation on a ceiling which can be a good 20C warmer then the floor level, even the above ballast I doubt will ever get to 90C during normal operation unless they are only good for a couple of years because whats the reduction in the ballasts MTBF isn't it somewhere in the area of 50% for every 10C over the rated operating temp so driving them to the max isn't a good idea (and it doesn't matter what type of ballast you use they should never be allowed to run at there maximum temperature rating)     
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