Nick.P
Member
- Location
- washington
Can a fitting [eg. liquid tight (L/T), Flex fitting] attach to a a)coupling, b)threaded hub/boss, c)Conduit body/condulet. In short, can one connect a Tapered thread (NPT) to a Straight thread (NPS*)? I see there are a few articles about this subject dating back to 1997. i have post link to the IAEI and to EC that go in to further detail. There are so many different answers that I have read/heard. mostly overall the answer is NO!! but the industry standard is YES?
I point out that a rigid conduit is NPT and a coupling is NPS, This is okay as it is UL listed 6. so this is good for wet locations and suitable for a low impedance bonding/grounding path. The NEC calls out NPT per ANSI/ASME B.1.B.20.1. The ANSI section states (NPT, NPSC, NPTR, NPSM, NPSL) are covered in this section. so i ask how would one make a raceway connection from a rigid conduit to a motor? no one has yet to answer this question with out combining NPT to NPS somewhere.
There is a few products that go from GRC to LFMC so this can solve some issues from GRC to LFMC but then the hub of the motor/device may have NPS threads.
i don't see why if the NEC says to use ANSI threads and all electrical threads are cut to this standard. this also meets the federal standards H28. why do i need do but another product or re-work any fitting and i still am unable to get a method of connection to a motor from the folks that bring up the issue. the company I work for has talk to UL about this and never tested in wet locations. the NEC states this is good in a Class 1 Div I location and UL article DFWT stays if its is good in a hazardous location is is more than suitable in a ordinary location.
please wise folks from the internet you'r my only hope!!!
There are several thread types ANSI B1.20.1 covered all of these and referred to as NPT:
NPT = National Pipe Thread
*NPS = National Pipe Straight
*NPSC = National Pipe Straight Coupling
*NPSM = Straight Mechanical Pipe Thread
346-8. Reaming and Threading. All cut ends of conduits shall be reamed or otherwise finished to remove rough edges. Where conduit is threaded in the field, a standard cutting die with a 3⁄4-in. taper per foot (1 in 16) shall be used.
FPN: See Standards for Pipe Threads, General Purpose (Inch), ANSI/ASME B.1.20.1-1983.
500-3(d) Threaded Conduit. All threaded conduit referred to herein shall be threaded with an NPT... Such conduit shall be made wrench-tight to prevent sparking when fault current flows through the conduit system, and ensure the explosionproof or dust ignition proof .... per ANSI/ASME B.1.20.1-1983
501-4. (a)(2) Flexible Connections. Where necessary to employ flexible connections, as at motor terminals, flexible fittings listed for Class I locations shall be used....Where provision must be made for limited flexibility, as at motor terminals, liquidtight flexible metal conduit with approved fittings, ... shall be used.
ANSI/ASME B.1.20.1-1983
1 INTRODUCTION International Assoc. of Elec. Inspectors
1.1 Scope This Standard covers dimensions and gaging of pipe threads of the following series: NPT, NPSC, NPTR, NPSM, NPSL
International Assoc. of Elec. Inspectors
https://iaeimagazine.org/magazine/2012/07/16/transitioning-between-raceways/
Electrical Contractors magazine-
https://www.ecmag.com/section/codes-standards/fittings-hubs
UL Listing –
UL 514b DWTT - Conduit Fittings http://productspec.ul.com/document.php?id=DWTT.GuideInfo
DFWV / AALZ - Electrical Equipment for Use in Ordinary Locations http://productspec.ul.com/document.php?id=AALZ.GuideInfo
KDER - Grounding and Bonding Equipment http://productspec.ul.com/document.php?id=KDER.GuideInfo
UL 6 DYIX - Rigid Ferrous Metal Conduit http://productspec.ul.com/document.php?id=DYIX.GuideInfo
ANSI B1.20.1 –
http://esh-docdb.fnal.gov/cgi-bin/R...ilename=Pages from B1-20-1_2013.pdf&version=6
Federal Standard H28 Machinery's Handbook 27th Edition http://www.nashua.edu/paradisem1/Machinery's Handbook 27th/27_Thread_09A.pdf
Fitting option 1 - https://www.emerson.com/en-sg/catalog/o-zgedney-4q-fm-lt-ozg-en-sg
Fitting option 2 - https://www.bptfittings.com/store/c...b-malleable-iron-body-with-steel-ferrule.html
T&B fitting
http://www.tnb-canada.com/en/pdf-ca...quidtight-flexible-metal-conduit-fittings.pdf
I point out that a rigid conduit is NPT and a coupling is NPS, This is okay as it is UL listed 6. so this is good for wet locations and suitable for a low impedance bonding/grounding path. The NEC calls out NPT per ANSI/ASME B.1.B.20.1. The ANSI section states (NPT, NPSC, NPTR, NPSM, NPSL) are covered in this section. so i ask how would one make a raceway connection from a rigid conduit to a motor? no one has yet to answer this question with out combining NPT to NPS somewhere.
There is a few products that go from GRC to LFMC so this can solve some issues from GRC to LFMC but then the hub of the motor/device may have NPS threads.
i don't see why if the NEC says to use ANSI threads and all electrical threads are cut to this standard. this also meets the federal standards H28. why do i need do but another product or re-work any fitting and i still am unable to get a method of connection to a motor from the folks that bring up the issue. the company I work for has talk to UL about this and never tested in wet locations. the NEC states this is good in a Class 1 Div I location and UL article DFWT stays if its is good in a hazardous location is is more than suitable in a ordinary location.
please wise folks from the internet you'r my only hope!!!
There are several thread types ANSI B1.20.1 covered all of these and referred to as NPT:
NPT = National Pipe Thread
*NPS = National Pipe Straight
*NPSC = National Pipe Straight Coupling
*NPSM = Straight Mechanical Pipe Thread
346-8. Reaming and Threading. All cut ends of conduits shall be reamed or otherwise finished to remove rough edges. Where conduit is threaded in the field, a standard cutting die with a 3⁄4-in. taper per foot (1 in 16) shall be used.
FPN: See Standards for Pipe Threads, General Purpose (Inch), ANSI/ASME B.1.20.1-1983.
500-3(d) Threaded Conduit. All threaded conduit referred to herein shall be threaded with an NPT... Such conduit shall be made wrench-tight to prevent sparking when fault current flows through the conduit system, and ensure the explosionproof or dust ignition proof .... per ANSI/ASME B.1.20.1-1983
501-4. (a)(2) Flexible Connections. Where necessary to employ flexible connections, as at motor terminals, flexible fittings listed for Class I locations shall be used....Where provision must be made for limited flexibility, as at motor terminals, liquidtight flexible metal conduit with approved fittings, ... shall be used.
ANSI/ASME B.1.20.1-1983
1 INTRODUCTION International Assoc. of Elec. Inspectors
1.1 Scope This Standard covers dimensions and gaging of pipe threads of the following series: NPT, NPSC, NPTR, NPSM, NPSL
International Assoc. of Elec. Inspectors
https://iaeimagazine.org/magazine/2012/07/16/transitioning-between-raceways/
Electrical Contractors magazine-
https://www.ecmag.com/section/codes-standards/fittings-hubs
UL Listing –
UL 514b DWTT - Conduit Fittings http://productspec.ul.com/document.php?id=DWTT.GuideInfo
DFWV / AALZ - Electrical Equipment for Use in Ordinary Locations http://productspec.ul.com/document.php?id=AALZ.GuideInfo
KDER - Grounding and Bonding Equipment http://productspec.ul.com/document.php?id=KDER.GuideInfo
UL 6 DYIX - Rigid Ferrous Metal Conduit http://productspec.ul.com/document.php?id=DYIX.GuideInfo
ANSI B1.20.1 –
http://esh-docdb.fnal.gov/cgi-bin/R...ilename=Pages from B1-20-1_2013.pdf&version=6
Federal Standard H28 Machinery's Handbook 27th Edition http://www.nashua.edu/paradisem1/Machinery's Handbook 27th/27_Thread_09A.pdf
Fitting option 1 - https://www.emerson.com/en-sg/catalog/o-zgedney-4q-fm-lt-ozg-en-sg
Fitting option 2 - https://www.bptfittings.com/store/c...b-malleable-iron-body-with-steel-ferrule.html
T&B fitting
http://www.tnb-canada.com/en/pdf-ca...quidtight-flexible-metal-conduit-fittings.pdf
