# Fluorescent 2x4 lay in's



## Steel24 (Mar 27, 2013)

Today I was called in to an office to fix a bunch of bad ballasts/lamps. The first 12 were t12 and I changed them to t8. No problem. Then I got to a newer part of building to find that there were 2-2x4 lay ins connected together via a flex conduit. In one of the fixtures they had 2 ballasts(1-4 lamp and 1-2 lamp). The other fixture had no ballast, just the wires fed through to the sockets. I had never seen this before and can't make sense of why anyone would do this?

Anyone use this style of fixture? And why? Makes changing the ballasts a pain in the butt!


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## BBQ (Nov 16, 2010)

They are called master and slave fixtures and they install fast, the whip comes pre-installed so you just hook up one end with wagos. 

But yeah servicing them is a pain.


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## Jlarson (Jun 28, 2009)

The slaves come pre-whipped huh? :brows: :lol:


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## BBQ (Nov 16, 2010)

Jlarson said:


> The slaves come pre-whipped huh? :brows: :lol:


Yeah, it takes all the fun out of it. :laughing:


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## frenchelectrican (Mar 15, 2007)

I have see that arrangement few time with master / slave units.

However let me give you a head up becarefull when you use the replacement ballast some will not work very well with M/S set up due the distance.

That you should check with the ballast manufacter to see what is the max distance it can able support the lamp without issue.

Merci,
Marc


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## Steel24 (Mar 27, 2013)

Thanks, I figured they were semi-common. I have just never seen them before. Learn something new everyday!


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## gmihok (Apr 29, 2013)

Instead of paying for two fixtures to have one ballast in them, you pay a higher cost for the master and lower cost for the salve. Used in big box retail and commercial application, also good for A/B switching.


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## davenc (Feb 20, 2013)

A few of the buildings I service have that setup. 3-lamp fixtures, one switch for outside lamps and the other for the middle lamp.


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## Spark Master (Jul 3, 2012)

I never seen that, or even heard of that setup before. One would think all fixtures need to be self contained.


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## Wireless (Jan 22, 2007)

Is there a sign on the outside of the fixture if it is master or a slave? I started opening the ceiling tiles to see how it is wired.


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## frenchelectrican (Mar 15, 2007)

Wireless said:


> Is there a sign on the outside of the fixture if it is master or a slave? I started opening the ceiling tiles to see how it is wired.


Once you pop your head inside the ceiling grid you will see the whips from each master / slave luminaire you can pretty much indentify it. some case it may have a quick connector on the top but most case you will have see where the incomming whips are located.

Very few lumiaires I know some will marked *M* or *S* as well so that will help you to make a note which unit it is.

Merci,
Marc


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## Wireless (Jan 22, 2007)

frenchelectrican said:


> Once you pop your head inside the ceiling grid you will see the whips from each master / slave luminaire you can pretty much indentify it. some case it may have a quick connector on the top but most case you will have see where the incomming whips are located.
> 
> Very few lumiaires I know some will marked M or S as well so that will help you to make a note which unit it is.
> 
> ...


That much I figured! Was asking if there is away to avoid that.


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## big2bird (Oct 1, 2012)

Spark Master said:


> I never seen that, or even heard of that setup before. One would think all fixtures need to be self contained.


Why is that?


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## JoeKP (Nov 16, 2009)

I never knew these actually existed. I have had the thought of making these as one of those random night thoughts. 
Would you be allowed to make these from existing fixtures or does that void the listing.


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## drumnut08 (Sep 23, 2012)

Wireless said:


> Is there a sign on the outside of the fixture if it is master or a slave? I started opening the ceiling tiles to see how it is wired.


Not , the ones I've come across and in all honesty it would just confuse the next electrician or likely maintenance man anyway , lol ! You'd need an arrow along with the master slave label telling you which is which . You find out soon enough when you open the fixture only to find no supply wires or ballast . First time I came across one of these I felt like curly from the three stooges " no wonder they don't have any water , there's wires on these pipes ! "


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## big2bird (Oct 1, 2012)

Wireless said:


> Is there a sign on the outside of the fixture if it is master or a slave? I started opening the ceiling tiles to see how it is wired.


Psst. The power goes into the master. The slave is fed from the master.


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