Plug Supplied Industrial Machinery
- Thread starter Elifyno
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ramsy
NoFixNoPay Electric
- Location
- LA basin, CA
- Occupation
- Service Electrician 2020 NEC
Re: Plug Supplied Industrial Machinery
Doesn't NFPA 70 430.42(C) permit this, if the overload device is an integral part of the motor/appliance.
Doesn't NFPA 70 430.42(C) permit this, if the overload device is an integral part of the motor/appliance.
Re: Plug Supplied Industrial Machinery
Thanks. I was focusing on other codes such as 430.108 which lead me to believe the plug/receptacle had to be HP rated even if the machine had an onboard disconnect. Am I to assume that a plug/receptacle that supplies a machine with a motor load is not always considered a disconnect?
We typically supply machines from single receptacle general purpose branch circuits but some of the codes had me wondering.
Thanks. I was focusing on other codes such as 430.108 which lead me to believe the plug/receptacle had to be HP rated even if the machine had an onboard disconnect. Am I to assume that a plug/receptacle that supplies a machine with a motor load is not always considered a disconnect?
We typically supply machines from single receptacle general purpose branch circuits but some of the codes had me wondering.
ramsy
NoFixNoPay Electric
- Location
- LA basin, CA
- Occupation
- Service Electrician 2020 NEC
Re: Plug Supplied Industrial Machinery
I agree with your read of 430.109(F). The cord & plug won't count as the disconnect unless it's a horsepower-rated attachment plug equal to motor horsepower.
But, with a nice looking controller, could a sharp AHJ be convinced to sign off on a cord & plug --lacking horspower-- as disconnect, via isolation switch equivelant 430.109(E), where marked "Do not operate under load"?
The guys on this forum with more motor/AHJ experience may be more helpful here.
[ December 23, 2005, 07:14 AM: Message edited by: ramsy ]
I agree with your read of 430.109(F). The cord & plug won't count as the disconnect unless it's a horsepower-rated attachment plug equal to motor horsepower.
But, with a nice looking controller, could a sharp AHJ be convinced to sign off on a cord & plug --lacking horspower-- as disconnect, via isolation switch equivelant 430.109(E), where marked "Do not operate under load"?
The guys on this forum with more motor/AHJ experience may be more helpful here.
[ December 23, 2005, 07:14 AM: Message edited by: ramsy ]
Re: Plug Supplied Industrial Machinery
ELIFYNO:
I would check with local AHJ with any questions. Now having said that....IMO you should not connect any motor or machine with a plug & receptacle not HP rated.
There is just too much potential for serious arcing with out HP rated plug & receptacle, which could cause some serious burns.
ELIFYNO:
I would check with local AHJ with any questions. Now having said that....IMO you should not connect any motor or machine with a plug & receptacle not HP rated.
There is just too much potential for serious arcing with out HP rated plug & receptacle, which could cause some serious burns.
plugman
Member
- Location
- Milwaukee, WI
Re: Plug Supplied Industrial Machinery
I agree with dlhoule. There is a considerable amount of extra testing that is required to have a plug and receptacle horsepower rated. The main test is 50 make and break operations at 6 times the motor FLA at rated voltage and a .5 power factor.
Some plugs and receptacles carry switch ratings and can act as the sole disconnecting means on a piece of equipment.
I agree with dlhoule. There is a considerable amount of extra testing that is required to have a plug and receptacle horsepower rated. The main test is 50 make and break operations at 6 times the motor FLA at rated voltage and a .5 power factor.
Some plugs and receptacles carry switch ratings and can act as the sole disconnecting means on a piece of equipment.
Re: Plug Supplied Industrial Machinery
I appreciate everyone's responses. I've read that the NEC code is considered a "challenging" document, but it seems to be turning into an engineering version of the tax code.
Based on NFPA 70 and 79 Which scenario is a code violation?
1. 10hp machine, onboard O.L., hinged screw cover electrical enclosure, supplied by a G.P. branch receptacle/plug.
2. Same as above, plus a HP rated safety switch next (adjacent) to the enclosure, not interlocked. Still G.P. plug supplied.
3. Same as #1, but the disconnect is a safety switch is on the other side of the machine (still visible). Still G.P. plug supplied.
4. Same as #1, but the disconnect is panel mounted in the enclosure and interlocked with the cover. Still G.P. plug supplied.
5. Same as #1, but the disconnect and supply is a HP rated plug and receptacle.
6. Same as #1, but add a panel mounted rotary disconnect, interlocked with the cover, and a HP rated plug/receptacle disconnect.
Can our AHJ approve any other scenario regardless of the common consensus made here? :roll:
I appreciate everyone's responses. I've read that the NEC code is considered a "challenging" document, but it seems to be turning into an engineering version of the tax code.
Based on NFPA 70 and 79 Which scenario is a code violation?
1. 10hp machine, onboard O.L., hinged screw cover electrical enclosure, supplied by a G.P. branch receptacle/plug.
2. Same as above, plus a HP rated safety switch next (adjacent) to the enclosure, not interlocked. Still G.P. plug supplied.
3. Same as #1, but the disconnect is a safety switch is on the other side of the machine (still visible). Still G.P. plug supplied.
4. Same as #1, but the disconnect is panel mounted in the enclosure and interlocked with the cover. Still G.P. plug supplied.
5. Same as #1, but the disconnect and supply is a HP rated plug and receptacle.
6. Same as #1, but add a panel mounted rotary disconnect, interlocked with the cover, and a HP rated plug/receptacle disconnect.
Can our AHJ approve any other scenario regardless of the common consensus made here? :roll:
Re: Plug Supplied Industrial Machinery
The guy plugging it in may not get flashed but whoever was standing next to the open panel would. I'd rather see a panel disconnect with interlock and branch receptacle for a supply. A label for "Do not Unplug Under Load" should suffice if there is a load break rated disconnect on the machine. These HP rated plug disconnects aren't a nema standard as far as I'm aware and don't provide any brand interchangeability in that regard. I'm sure they'd be good if all you were doing was plugging a motor in, but a machine with a control enclosure should have an interlock on the door. I think its misleading for these manufacturers to tout code compliance and not reference NFPA 79 at all. Make them a NEMA standard and I'll quit flogging the dead horse the AHJ rode in on.
The guy plugging it in may not get flashed but whoever was standing next to the open panel would. I'd rather see a panel disconnect with interlock and branch receptacle for a supply. A label for "Do not Unplug Under Load" should suffice if there is a load break rated disconnect on the machine. These HP rated plug disconnects aren't a nema standard as far as I'm aware and don't provide any brand interchangeability in that regard. I'm sure they'd be good if all you were doing was plugging a motor in, but a machine with a control enclosure should have an interlock on the door. I think its misleading for these manufacturers to tout code compliance and not reference NFPA 79 at all. Make them a NEMA standard and I'll quit flogging the dead horse the AHJ rode in on.
plugman
Member
- Location
- Milwaukee, WI
Re: Plug Supplied Industrial Machinery
I think that once the next edition of NFPA 79 comes out, you will be seeing more and more references to this document by manufacturers. There will be changes to sections 5.3.2 and 5.3.3 that should add clarificaiton as to what types of plugs and receptacles can be used as a disconnecting device.
I think that once the next edition of NFPA 79 comes out, you will be seeing more and more references to this document by manufacturers. There will be changes to sections 5.3.2 and 5.3.3 that should add clarificaiton as to what types of plugs and receptacles can be used as a disconnecting device.
Re: Plug Supplied Industrial Machinery
I still do not like idea of plugging in any 440 Volt plugs with power on outlet, unless HP rated.
If that panel had disconnect in off position and you had a fault on line side of disconnect or in the cord or male plug, the arc will be at the point of insertion.
I still do not like idea of plugging in any 440 Volt plugs with power on outlet, unless HP rated.
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