NEC heater chart ????
- Thread starter otaiam
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hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: NEC heater chart ????
Call a supply house or go to the manufacture of the motor starter assy. web site as they wont be found in the NEC these are manufacture sized to the motor starter, they are not interchangable and they will have differant numbers for differant manufactures. and they are sized for the full load amps on the motor plate.
Call a supply house or go to the manufacture of the motor starter assy. web site as they wont be found in the NEC these are manufacture sized to the motor starter, they are not interchangable and they will have differant numbers for differant manufactures. and they are sized for the full load amps on the motor plate.
david
Senior Member
- Location
- Pennsylvania
Re: NEC heater chart ????
III. Motor and Branch-Circuit Overload Protection
430.31 General.
III. Motor and Branch-Circuit Overload Protection
430.31 General.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: NEC heater chart ????
Yes there is It is found in 430.31-44 in the 2002 NEC but the bacic rule is to set the amprage at the full run amps of the motor or what it says in 430.32:
430.32 Continuous-Duty Motors.
(A) More Than 1 Horsepower. Each continuous-duty motor rated more than 1 hp shall be protected against overload by one of the means in 430.32(A)(1) through (A)(4).
(1) Separate Overload Device. A separate overload device that is responsive to motor current. This device shall be selected to trip or shall be rated at no more than the following percent of the motor nameplate full-load current rating:
Motors with a marked service factor 1.15 or greater 125%
Motors with a marked temperature rise 40?C or less 125%
All other motors 115%
this allows for the full power of the motor without allowing for it to be overloaded. now if there is a need for a reduced level of output then it would have to be caculated. remember overload protection is differant from short circuit protection of the conductors feeding this motor starter which can be:
Nontime Delay Fuse1 300%
Dual Element (Time-Delay) Fuse1 175%
Instantaneous Trip Breaker 800%
Inverse Time Breaker2 250%
Over the full load ratting of the motor.
Hope this is what your looking for?
[ August 19, 2003, 01:41 AM: Message edited by: hurk27 ]
Yes there is It is found in 430.31-44 in the 2002 NEC but the bacic rule is to set the amprage at the full run amps of the motor or what it says in 430.32:
430.32 Continuous-Duty Motors.
(A) More Than 1 Horsepower. Each continuous-duty motor rated more than 1 hp shall be protected against overload by one of the means in 430.32(A)(1) through (A)(4).
(1) Separate Overload Device. A separate overload device that is responsive to motor current. This device shall be selected to trip or shall be rated at no more than the following percent of the motor nameplate full-load current rating:
Motors with a marked service factor 1.15 or greater 125%
Motors with a marked temperature rise 40?C or less 125%
All other motors 115%
this allows for the full power of the motor without allowing for it to be overloaded. now if there is a need for a reduced level of output then it would have to be caculated. remember overload protection is differant from short circuit protection of the conductors feeding this motor starter which can be:
Nontime Delay Fuse1 300%
Dual Element (Time-Delay) Fuse1 175%
Instantaneous Trip Breaker 800%
Inverse Time Breaker2 250%
Over the full load ratting of the motor.
Hope this is what your looking for?
[ August 19, 2003, 01:41 AM: Message edited by: hurk27 ]
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: NEC heater chart ????
Sory David we posted at the same time
[ August 19, 2003, 01:52 AM: Message edited by: hurk27 ]
Sory David we posted at the same time
[ August 19, 2003, 01:52 AM: Message edited by: hurk27 ]
luke warmwater
Senior Member
Re: NEC heater chart ????
To make it easy, try a supply house that carries Square D.
Square D makes a 'Motor Data Calculator' based on the current code. The supply house that I get them from gives them out free of charge.
It's pretty simple to use, just set the H.P. rating and read the data.
Thermal units can be more accurately selected using the table that comes with the starter and full load current marked on the motor nameplate.
To make it easy, try a supply house that carries Square D.
Square D makes a 'Motor Data Calculator' based on the current code. The supply house that I get them from gives them out free of charge.
It's pretty simple to use, just set the H.P. rating and read the data.
Thermal units can be more accurately selected using the table that comes with the starter and full load current marked on the motor nameplate.
Re: NEC heater chart ????
there are several manufacturers out there that can help, allen bradley, square d, ge, furnace, as well as others. it is important to remenber that each manufacturer has their own unique way of sizing motor heaters. don't use a square d chart and goto an allen bradley office and get a set of heaters based on the square d chart. you need to confirm with them what they recommend. each of them has their own charts to go by.
there are several manufacturers out there that can help, allen bradley, square d, ge, furnace, as well as others. it is important to remenber that each manufacturer has their own unique way of sizing motor heaters. don't use a square d chart and goto an allen bradley office and get a set of heaters based on the square d chart. you need to confirm with them what they recommend. each of them has their own charts to go by.
luke warmwater
Senior Member
Re: NEC heater chart ????
pwhite is correct. After reading my post, I realize that I didn't mention to use the Square D chart for Square D starters.
As he mentions, other companies have them for use on their own starters, including Cutler Hammer.
pwhite is correct. After reading my post, I realize that I didn't mention to use the Square D chart for Square D starters.
As he mentions, other companies have them for use on their own starters, including Cutler Hammer.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: NEC heater chart ????
Hey guys dont get carryied away He was looking for where to find the max ovl that can be used for a given motor of a given hp. this info is for a test that he had today (hope he passed it) I thought the same thing when I first read the question. but relized what he wanted was what the NEC wanted and that was 430.31-44
Hey guys dont get carryied away He was looking for where to find the max ovl that can be used for a given motor of a given hp. this info is for a test that he had today (hope he passed it) I thought the same thing when I first read the question. but relized what he wanted was what the NEC wanted and that was 430.31-44
luke warmwater
Senior Member
Re: NEC heater chart ????
wayne, oops, you're right.
wayne, oops, you're right.
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