What is an “RIB”?

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charlie b

charlie b

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We have a question from an EC who wants us to confirm that a VFD is not needed for a specific application (in fact, it is not), and to confirm that they can instead install an RIB with a manual motor starter. Other than the baby backs that I plan to run though the smoker on Sunday, I do not know what RIB could mean. The best I could get from Bing was “Relay in a Box.” But I can’t guess what such a thing would do, and why it would be named in addition to the motor starter. Can anyone clue me in?
 
An RIB is like an ice cube relay but all the connections are sealed up in a nice little box so you don't need an extra j box. Very handy.

In the picture Lucky posted the leads you see are for the coil, N O, N C. The EC could just mount it right to the side of the starter and, perhaps, use 24V to the coil on the RIB to get a higher voltage to the coil on the starter.

So is the EC saying there is no need to change speeds so a regular starter will work?
 
Thanks for the replies. This is for a 1.5hp bathroom exhaust fan in a high rise office building. The mechanical engineer dropped the requirement for a VFD late in the design process, but the electrical plans still show a VFD (not my project :happyno:). The EC is simply asking for clarification, but he used a term that I had not encountered before.
 
charlie b said:
Thanks for the replies. This is for a 1.5hp bathroom exhaust fan in a high rise office building. The mechanical engineer dropped the requirement for a VFD late in the design process, but the electrical plans still show a VFD (not my project :happyno:). The EC is simply asking for clarification, but he used a term that I had not encountered before.
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For a 115-230V 1.5HP EFM, chances are good that a properly-rated r.i.b. can used in lieu of an r.i.b. and starter.
 
Wait a minute... 1.5HP is a HUGE bathroom fart fan! Are you sure it isn't .15HP?

If it truly is 1-1/2HP, then who is making the decision NOT to use a VFD? Because from an HVAC standpoint, the VFD may have been necessary to maintain a specific static pressure balance in the building by being controlled through the BMS system. Running a 1.5HP bathroom exhaust fan manually could cause the building to pull negative air pressure and even with just an inch of water column of negative pressure, doors that open out will be sucked in closed, causing people to panic that they can't get out and call the fire department, who will break the windows to "save" them, then you get hit with the bill for everything.

I know all this because... it happened to me!
 
Jraef said:
Wait a minute... 1.5HP is a HUGE bathroom fart fan! Are you sure it isn't .15HP?

If it truly is 1-1/2HP, then who is making the decision NOT to use a VFD? Because from an HVAC standpoint, the VFD may have been necessary to maintain a specific static pressure balance in the building by being controlled through the BMS system. Running a 1.5HP bathroom exhaust fan manually could cause the building to pull negative air pressure and even with just an inch of water column of negative pressure, doors that open out will be sucked in closed, causing people to panic that they can't get out and call the fire department, who will break the windows to "save" them, then you get hit with the bill for everything.

I know all this because... it happened to me!
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:thumbsup:
 
Jraef said:
Wait a minute... 1.5HP is a HUGE bathroom fart fan! Are you sure it isn't .15HP?

If it truly is 1-1/2HP, then who is making the decision NOT to use a VFD? Because from an HVAC standpoint, the VFD may have been necessary to maintain a specific static pressure balance in the building by being controlled through the BMS system. Running a 1.5HP bathroom exhaust fan manually could cause the building to pull negative air pressure and even with just an inch of water column of negative pressure, doors that open out will be sucked in closed, causing people to panic that they can't get out and call the fire department, who will break the windows to "save" them, then you get hit with the bill for everything.

I know all this because... it happened to me!
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the law of unintended consequences really sucks.
 
Fulthrotl said:
the law of unintended consequences really sucks.
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Literally in that case!

It was a facility in Bellevue Washington that made defibrillators and after retrofitting the HVAC fans with VFDs, we (really, the HVAC guy I worked with) forgot the bathroom vent fans as part of the air balancing issues. So on commissioning, when nobody was working in the building, everything worked fine. But the next day when all the employees showed up and started using the bathrooms, the fans pulled a negative pressure on the building. By the time the BMS had the supply and return fan speeds adjusted, someone had tried to go out one of the doors designated as a fire exit, so it opened outward, and when they couldn't open it they freaked out, panicked and hit the fire alarm. The fire fighters tried the doors and immediately smashed the glass with axes (they thought there really was a fire of course). I got hit for replacing the doors, plus the fire dept. hit me with a false alarm charge of $250.
 
George Stolz said:
On that note, it's good to avoid the Chinese knockoffs, Relay in a Bag. I am never trying that again.
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Lol! I use RIBS frequently. They even make a nice mechanically latching model that's rated for electronic ballasts.

I agree with the previous poster that a VFD should be used if the building's HVAC is computer controlled. You should also consider how your HVAC ties in with the fire panel. it's always good for the GC to organize a meeting with the EC and MCs. I often request one otherwise.
 
Or how about relay in a jar? I actually pulled this out of a drop ceiling in a guy's basement!

20150603_170333.jpg

Yes, that's an olive jar! :lol:
 
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