ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Where is Everyone?
by luckyshadow - 11/21/21 10:14 AM
It's been an interesting career
by The Watt Doctor - 11/19/21 09:56 AM
Well I am back to stay (nearly 6 years)
by The Watt Doctor - 11/19/21 09:17 AM
Motor Load Relationships Between Fans and Pumps
by The Watt Doctor - 11/18/21 09:24 AM
GFCI's pops in large numbers
by dsk - 11/05/21 06:45 AM
New in the Gallery:
240/208 to a house
240/208 to a house
by wa2ise, October 9
Now you know.
Now you know.
by Tom_Horne, September 7
Who's Online Now
0 members (), 42 guests, and 13 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Joined: Jun 2005
Posts: 14
S
sccat Offline OP
Member
Is there a Thermal Relay in a DOL starter for "staircase pressurization fan"?
When motor overload happens,will the Thermal Relay cut off the contactor?

Joined: Apr 2002
Posts: 7,283
Likes: 3
Member
Your second question: Thermal OLs 'open', and the motor starter opens (Off).

First question may require more than the NEC, as staircase pressurization is Building & Fire Safety Codes. I suggest that you contact the local AHJs in whatever area you are working in. My opinion would be no OLs, just short circuit protection as this is a life safety item, perhaps like a fire pump. Just my opinion.



John
Joined: Jun 2005
Posts: 14
S
sccat Offline OP
Member
Is there a Thermal Relay in a DOL starter for "staircase pressurization fan"?
When motor overload happens,will the Thermal Relay cut off the contactor?

Joined: Jun 2004
Posts: 1,273
T
Member
Only ONCE did I have to build such a circuit.

The AHJ determined that such a blower is NOT a life essential device.

So the OL heaters were left in place.

-----

Each situation is going to be a Life Safety issue. It's outside the NEC.

----

WRT smaller ( 1hp or less ) thermal overloads lead directly to integral drop-out from the load.

Not uncommonly, they reset, automatically, when the temp drops they re-trigger. They DO NOT interact with any contactor what so ever.

These beasties interrupt line current -- and then restore it.

These motors are so small that contactors are uncommon.



Tesla
Joined: Jul 2002
Posts: 8,412
Likes: 3
Member
Originally Posted by sccat
Is there a Thermal Relay in a DOL starter for "staircase pressurization fan"?
When motor overload happens,will the Thermal Relay cut off the contactor?


In a Direct On Line starter, your only real protection is thermal via the overloads at the base of the contactor.
This should by rights open the control circuit and shut everything off, unless it has been poorly designed or wired.

This is first year apprentice stuff, why do you ask?

Joined: Jun 2005
Posts: 14
S
sccat Offline OP
Member
Some people think that "staircase pressurization fan" is a Life Safety Equipment as "fire pump".

Joined: Apr 2002
Posts: 7,283
Likes: 3
Member
Sccat:

You have this posted in the NEC section from 9/22/2011, which has one response. I'll merge the two together.

You're right!! Now, it will depend on 'who' the 'some people' are!!

The best solution I would suggest is to speak to the local AHJ about this. IF the ventilation system is considered 'life safety' or not.

Last edited by HotLine1; 09/27/11 08:36 AM. Reason: prep to merge

John
Joined: Jun 2005
Posts: 14
S
sccat Offline OP
Member
NFPA 92A-2006 Standard for Smoke-Control Systems Utilizing Barriers and Pressure Differences

Annex D Fire Fighters’ Smoke-Control Station Considerations

Control actions issued from the FSCS should not override or bypass devices and controls intended to protect against electrical overloads, provide for personnel safety, and prevent major system damage.

Is "Staircase Pressurization Fan " a part of "Smoke-Control Systems"?

Joined: Apr 2002
Posts: 7,283
Likes: 3
Member
Again, I say...talk to the local AHJ!

BTW, you profile states your location as "CHN", would you care to elaborate on that please?



John

Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
CDS
CDS
Nicholson Ga
Posts: 34
Joined: June 2006
Top Posters(30 Days)
Admin 3
dsk 2
Popular Topics(Views)
286,222 Are you busy
218,658 Re: Forum
204,851 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5