FSD's per ckt

[Alwayslearningelec]

I am trying to find out howm many FSD's I can put on a 208v ckt. They are not shown on the electrical floorplans, only on the panels schedule and they show (4) 20a ckts for them. There are (90) on the mechanicals. How can I figure the connected load or how many i can put on one ckt. I looked on the mech schedules for info on the fsd's but don't see any. Thanks very much.

 

[roger3829]

I don't know what a FSD is?

 

[Alwayslearningelec]

Sorry Roger. Fire Smoke Damper

 

[dhalleron]

It's been a long time since I worked with them, but the ones I worked with were powered all the time. When they lost power they closed. It was a small damper motor and we controlled it with a relay that handled 7 amps or less. I can't remember what the actual damper motor would draw. I'm sure it will vary per damper size.

Someone on the job must have some info on which damper is going to be installed. Like anything, if you don?t have the specs on the exact model that is going to be installed Murphy will not be good to you if you guess.

 

[cadpoint]

FSD's = Fire Smoke Dampers ? ? ?

This really needs to be determeined between the HVAC/mechanical contractor and your company.

It's one of those situations where some understanding needs to be gained by having to deal with another contractor.

A lot of times its designed as required but no thought is given to it as to who's going to apply the work.

Some examples could be that the mech. needs just 4 circuits, they need a circuit at a certain point of use(to be determined), and your company is not responsible to hook it up! They need circuits to all points and you do need to hook them up!
They only need four circuits to a control or multiply control boxes and all the fire dampers are controled with low voltage, you might or might not need to run a conduit to point of use. Or your conduit will only be used by the mechanical low voltage technician.

If the HVAC is a large system they might have various zones requiring split up the circuits.

Just about any combinatios of how to get this done might apply, it just depends on the contractor and who's going to get out in front of this to identify the problem, and who's going to pay to get this resolved and the responsbility assigned.

Maybe an RFI is the way to go?

 

[Alwayslearningelec]

FSD's = Fire Smoke Dampers ? ? ?

This really needs to be determeined between the HVAC/mechanical contractor and your company.

It's one of those situations where some understanding needs to be gained by having to deal with another contractor.

A lot of times its designed as required but no thought is given to it as to who's going to apply the work.

Some examples could be that the mech. needs just 4 circuits, they need a circuit at a certain point of use(to be determined), and your company is not responsible to hook it up! They need circuits to all points and you do need to hook them up!
They only need four circuits to a control or multiply control boxes and all the fire dampers are controled with low voltage, you might or might not need to run a conduit to point of use. Or your conduit will only be used by the mechanical low voltage technician.

If the HVAC is a large system they might have various zones requiring split up the circuits.

Just about any combinatios of how to get this done might apply, it just depends on the contractor and who's going to get out in front of this to identify the problem, and who's going to pay to get this resolved and the responsbility assigned.

Maybe an RFI is the way to go?

Thanks Cad. You mention low voltage wiring as one scenario and bringing 120v to al local area. I believe the fsd's have to be wired with 120v so I'm not sure what you mean by bringing low voltage to them??? Thanks.

 

[cadpoint]

Thanks Cad. You mention low voltage wiring as one scenario and bringing 120v to al local area. I believe the fsd's have to be wired with 120v so I'm not sure what you mean by bringing low voltage to them??? Thanks.

Right my mistake to mention LV, but the problem still exists in quailfing what needs to be done.

The point is that most mechanicals (on larger jobs) have a crew to do their wiring.

Most HVAC Co.'s will assume their own liability when it comes to their matters.

 

[augie47]

As others have noted, you need to check with the Mechanical Contractor for specifics. As a rule they use very little power. Here is one link that shows a 35 watt model.
http://www.ruskin.com/catalog/servefile.aspx?id=1662

 

[skeshesh]

As with anything else you need to get a cut-sheet and use the rating. FSDs, dampers, etc. can vary greatly in size from commercial to industrial applications and the operation requirements can vary as such. Find the mechanical guy and give him a ring. Sometime's they're clueless so you may need to grab the model number and give mfg a call - it's not going to be that difficult to find though.

 

[bluesmoke...oops]

Check with mech.

I've seen them where they need 120, and I've seen them where mech just wants a low volt transformer with xx VAs available.

Also, I believe that some of the dampers can be heat fail as well can't they? Like basically melt a linkage and fall closed?

 

[Alwayslearningelec]

Check with mech.

I've seen them where they need 120, and I've seen them where mech just wants a low volt transformer with xx VAs available.

Also, I believe that some of the dampers can be heat fail as well can't they? Like basically melt a linkage and fall closed?

You mean not requiring power and melt a fusible link??? Thanks.

 

[sameguy]

RFI if bidding get with hvac if your on the job; some may be unpowered.

 

[bluesmoke...oops]

You mean not requiring power and melt a fusible link??? Thanks.

Yeah that's what I was trying to say. And even if they are electric, they don't consume a lot of energy to stay open.

 

[cschmid]

all of the FSD's I have encountered have been part of another system and all we needed was to supply was the 120 volt power to the control box. normally it was a dedicated 20amp circuit for each control box. The FSD's were all 24 volt because they stay energized constantly except during a fault. 120 volt FSD's would be very costly to maintain I would double check this before I bid it as it could be costly to you. If there is a problem at time of commissioning you are responsible for the hassle involved.

 

[skeshesh]

Sometimes I have a hard time looking at it from a contractors point of view... if you are bidding as an electrical sub-contractor, then you should still be able to get a hold of a full set. Check out the mechanical floor plans and details, surely they will call out a fusible link if that's what they're specifying. Be careful because there are projects where a variety is used so keep looking even if you find some with a fusible link to make sure to bid correctly. If you find some that require a connection, try to stop the keynotes that call it out on the floor and count them up.