EOL-Relay and attic wiring

[lleo]

Hi, as I moved to the implementation phase of my shiny new fire-alarm and security system, encountered practical issues, that I could not locate an answer:
 
Suppose I will have a 4-wire smoke detector loop, with an EOL-Relay for power supervision, and the smoke detector does not have the relay built in, does this relay needs to be wired back to panel? If not, what are the wiring rules for this, i.e. does it need to be in a box, accessible from room, simply tucked in the insulation etc?
I plan to surface mount the smokes, with the wire going through the drywall.
 
 
Are there any guides, rules in running low-voltage wires in an attic? I would like to avoid drilling through joists. Simply laying it on top?
Thanks a lot, and sorry for the noob questions.

 

[gatchel]

You'll usually see this in the installation paperwork included with you EOLR.
 
Wiring
NOTE: All wiring must conform to applicable local codes,
ordinances, and regulations.
 
Do you know what NEC you are on?

 

[JimS]

I am also looking at this...  Not sure if a box is required but it seems like a good idea - it makes the unit easy to service when needed.  Putting up a box is easy and cheap so why not?  The relay doesn't normally get wired back to the panel.  It can but requires a run from the end detector back to the panel - seems like a waste of effort and cable.
 
You should not drill members of trusses.  If the local inspector doesn't like it you can get into all sorts of engineering documentation for repair.  Regular joists aren't as critical, especially for small holes but it's a lot of extra work drilling all those holes.  Generally you can't just run the wire on top either.  The logic is that people can walk on it and/or it can get damaged by things bumping into it, etc.  Generally a board is put parallel to the wire run and the wire is tacked to the side of it.  They may even like to see a board on each side.  Here we can't run wires on the bottom of joists without a running board either (like where you have a drop ceiling or crawl space).  Best to talk to the local inspectors about what they expect. 

 

[apostolakisl]

As far as your wiring runs, how they are secured and where they are located, that is pretty much up to your local inspector.
 
As far as running the relay wire back to the panel, no.  You use the power after the last detector in the series to power the relay, and you use the signal wires on the NO side of the relay as your supervision, along with an EOL resistor.  You do not use a separate zone to monitor the power status of the relay.  So if any of the 4 wires fails, you will get a "trouble" on that zone.
 
Just a note, I used the GE 400 series smokes, and they have a model with the supervising relay built-in, this is nice and clean and easy and cheap and just the best way to do it in my opinion.  You can get the GE ones with sounders, aux relays, supervising relays, different types of heat, and various combos of those items.

 

[lleo]

Thanks for your replies.
The town lists these as in effect, so it would be NEC 2008

• 
  
  
  
  International Building Code, 2009 New Jersey Edition
  
  
  
  
• 
  
  International Residential Code 2009 New Jersey Edition
  
  
• 
  
  National Standard Plumbing Code, 2009
  
  
• 
  
  National Electric Code, 2008
  
  
• 
  
  International Mechanical Code, 2009
  
  
• 
  
  International Fuel Gas Code, 2009
  
  
• 
  
  2009 International Energy Conservation Code – New Jersey Edition
   
  
  

I have the System Sensor smokes, and these do not have EOL-Relay built in. So if it is not run back to panel, tucking it in a ceiling box to which the smoke is mounted should be OK?

 

[apostolakisl]

OK, I thought you were asking something different.  Yes, the relay physically goes at or near the last detector.  I think you mentioned you were just surface mounting your detectors, but for the last one I would get on old construction box, cut it in to the sheetrock and use that space for the relay and then mount the detector over the top..

 

[lleo]

Thanks, this is helpful.

Now about the wiring in the unfinished attic: can I go up from the attic floor level and run it on the underside of rafters? Can I use a conduit laid across the joists?

I have a good sense of what is done for new construction, but retrofit work I guess is different. My attic has barely standing room in the middle, and except for related work, does not sees any traffic. I will use an interior wall cavity to run cabling from basement to attic. From there I have a straight run of about 45 feet where I will drop some of cables and spread out the rest. For about 5@cat6 cable, 18@22/4 and 1 or 2 18/4 cable I would have to drill a 2" hole in each joist which I don't like.

 

[JimS]

The underside of rafters is good to avoid it getting stepped on and such but I can't speak for if it passes local rules.  Then there is getting it from the attic floor to the rafters.  I ran wiring up truss members but if its an older house you may not have trusses.  Running it in conduit or along side a board is generally accepted as a means of protection, which is the issue as I understand it.  Since it is low voltage wiring the local authority may not care - they didn't seem to where I am.  They often don't but to be sure you would need to check with local people.  I don't think it generally matters that the attic is small.
 
If protection is not required I would  at least place it off to the side so it is unlikely to be walked on when crawling around in the attic.
 
If you know what is done in new construction why not just do that?  That is the safest from a standpoint of what is acceptable in your location. 

 

[apostolakisl]

Around here, there is no consideration for your LV cabling, just that when it penetrates a firewall it is properly sealed.  So it just gets run wherever it is out of harms way.

 

[lleo]

If you know what is done in new construction why not just do that?

 
My home is a large, sprawling single-story ranch-style home, where from one end to the other length-wise is 90 feet. My wiring closet is at the opposite end of bedrooms. Beside the labor of disturbing insulation for all this length, drilling through just about each and every joist does not seem the best idea. I also have large sections of unsupported ceilings where just walking in the attic is causing flexing in the ceiling.
Most of the electrical cabling is run in the basement, I might just do also that for the LV wires.

 

[lleo]

This thread so far has been very helpful. I waiting a call back from the electrical official from my town, and will get his input on this.
a follow-up question on conduits in attic: would something like 2" grey pvc conduit suffice for crossing on top large section of attic floor joist?

 

[apostolakisl]

This thread so far has been very helpful. I waiting a call back from the electrical official from my town, and will get his input on this.
a follow-up question on conduits in attic: would something like 2" grey pvc conduit suffice for crossing on top large section of attic floor joist?

 
I'm not going to say for sure what your inspector wants.  But I have lived in 3 states in the last 20 years and never seen wires in the attic run in conduit in a residence.

 

[Del91574]

You can, if you wanted to, bring 4 conductors back from the last detector to the panel and install the EOL relay in the panel and still conform, Typically, most will install in a box or free air at the last detector, as allowed by code in your area or typical installation customs.
 
Conduit can be run, however it's generally a lot of effort and expense to do, assuming that it is only for physical protection. Most will secure the wiring to the framing and call it a day.