Sprinkler systems

[ProjectSafety]

When is it permissible (if it is)to install a water sprinkler system coverage over electrical equipment such as distribution systems, MCCs, electric motors, etc. A fire chief is mandating that a wet system be installed over all electrical equipment in a sewage treatment facility. All of the distribution cabinets, MCCs are top vented and the motors have water resistant housings but are not water proof or submersible.

 

[bphgravity]

Re: Sprinkler systems

Its always permitted as far as the NEC is concerned. 110.26(F)(1)(c) permits sprinkler protection however the piping must not enter the dedicated equipment space also defined by this section.

What is a "wet system"?

 

[ed downey]

Re: Sprinkler systems

Bryan,

I believe he is talking about a "wet system" as one with water in the sprinkler pipe (less expensive $2/SF used in office or non critical environments). In lieu of a "dry system" which would have air in the system and until the air pressure leaves the system the sprinkler piping will not have water in it (more expensive $5/SF used in data centers, and critical equipment areas).

Ed

 

[don_resqcapt19]

Re: Sprinkler systems

Most dry systems are used in areas where the temperature drops below freezing. I don't know why they would be that much more expensive...all you are adding is a small air compressor and a dry system valve.
Don

 

[infinity]

Re: Sprinkler systems

The dry type systems that I've seen are typically in IT rooms. They are sometimes called pre-action systems. The water will not flow until after the sprinkler head is activated and an initiation device such as a smoke detector is also activated. This ensures that a broken sprinkler pipe can not flood the place.