Hi, I have a doubt about the code and if I am allowed or not to install a general purpose enclosure with an emergency shutdown (ESD) push button in a C1/D2.
I am looking at 501.150...
501.150 Signaling, Alarm, Remote-Control,
and Communications Systems.
(B) Class I, Division 2. In Class I, Division 2 locations, signaling, alarm, remote-control, and communications systems shall comply with 501.150(B)(1) through (B)(4).
(1) Contacts. Switches, circuit breakers, and make-and-break contacts of pushbuttons, relays, alarm bells, and horns shall have enclosures identified for Class I, Division 1 locations in accordance with 501.105(A).
Exception: General-purpose enclosures shall be permitted if current-interrupting contacts are one of the following:
(1) Immersed in oil
(2) Enclosed within a chamber hermetically sealed against
the entrance of gases or vapors
(3) In nonincendive circuits
(4) Part of a listed nonincendive component
So this circuit is a non-incendive circuit, with this in mind, I should be allowed to use a general purpose enclosure with an ESD push button? Also I would not need a seal (probably just for the boundary) since I do not have an explosion proof enclosure.
What confuses me is 501.115...
501.115 Switches, Circuit Breakers, Motor Controllers,
and Fuses.
(B) Class I, Division 2. Switches, circuit breakers, motor controllers, and fuses in Class I, Division 2 locations shall comply with 501.115(B)(1) through (B)(4).
(1) Type Required. Circuit breakers, motor controllers, and switches intended to interrupt current in the normal performance of the function for which they are installed shall be provided with enclosures identified for Class I, Division 1 locations in accordance with 501.105(A), unless general-purpose enclosures are provided and any of the following apply:
(1) The interruption of current occurs within a chamber hermetically sealed against the entrance of gases and vapors.
(2) The current make-and-break contacts are oil-immersed and of the general-purpose type having a 50-mm (2-in.) minimum immersion for power contacts and a 25-mm (1-in.) minimum immersion for control contacts.
(3) The interruption of current occurs within an enclosure, identified for the location, and marked “Leads Factory Sealed,” or “Factory Sealed,” or “Seal not Required,” or equivalent.
(4) The device is a solid state, switching control without contacts, where the surface temperature does not exceed 80 percent of the autoignition temperature in degrees Celsius of the gas or vapor involved.
So the above is also talking about enclosures but does not list the non-incendive exception.... Is this "enclosure" different from the above "enclosure"? I think 501.115 is talking about the encasing of the switch itself correct? Not the actual enclosure as in junction box, panel, etc...
So if I understand correctly, I would be allowed to install a general purpose enclosure, with no end seal... And inside an ESD pushhbutton contact, which I would be able to use one of the exceptions of 501.115 for C1/D2 . In other words, a hermetically sealed pushbutton would be ok.
If I install a regular pushbutton with the non-incendive circuit, I would need to install per 501.105(A) which mentions having explosion proof, purged or pressurized.
Thanks in advance...
Yogi
I am looking at 501.150...
501.150 Signaling, Alarm, Remote-Control,
and Communications Systems.
(B) Class I, Division 2. In Class I, Division 2 locations, signaling, alarm, remote-control, and communications systems shall comply with 501.150(B)(1) through (B)(4).
(1) Contacts. Switches, circuit breakers, and make-and-break contacts of pushbuttons, relays, alarm bells, and horns shall have enclosures identified for Class I, Division 1 locations in accordance with 501.105(A).
Exception: General-purpose enclosures shall be permitted if current-interrupting contacts are one of the following:
(1) Immersed in oil
(2) Enclosed within a chamber hermetically sealed against
the entrance of gases or vapors
(3) In nonincendive circuits
(4) Part of a listed nonincendive component
So this circuit is a non-incendive circuit, with this in mind, I should be allowed to use a general purpose enclosure with an ESD push button? Also I would not need a seal (probably just for the boundary) since I do not have an explosion proof enclosure.
What confuses me is 501.115...
501.115 Switches, Circuit Breakers, Motor Controllers,
and Fuses.
(B) Class I, Division 2. Switches, circuit breakers, motor controllers, and fuses in Class I, Division 2 locations shall comply with 501.115(B)(1) through (B)(4).
(1) Type Required. Circuit breakers, motor controllers, and switches intended to interrupt current in the normal performance of the function for which they are installed shall be provided with enclosures identified for Class I, Division 1 locations in accordance with 501.105(A), unless general-purpose enclosures are provided and any of the following apply:
(1) The interruption of current occurs within a chamber hermetically sealed against the entrance of gases and vapors.
(2) The current make-and-break contacts are oil-immersed and of the general-purpose type having a 50-mm (2-in.) minimum immersion for power contacts and a 25-mm (1-in.) minimum immersion for control contacts.
(3) The interruption of current occurs within an enclosure, identified for the location, and marked “Leads Factory Sealed,” or “Factory Sealed,” or “Seal not Required,” or equivalent.
(4) The device is a solid state, switching control without contacts, where the surface temperature does not exceed 80 percent of the autoignition temperature in degrees Celsius of the gas or vapor involved.
So the above is also talking about enclosures but does not list the non-incendive exception.... Is this "enclosure" different from the above "enclosure"? I think 501.115 is talking about the encasing of the switch itself correct? Not the actual enclosure as in junction box, panel, etc...
So if I understand correctly, I would be allowed to install a general purpose enclosure, with no end seal... And inside an ESD pushhbutton contact, which I would be able to use one of the exceptions of 501.115 for C1/D2 . In other words, a hermetically sealed pushbutton would be ok.
If I install a regular pushbutton with the non-incendive circuit, I would need to install per 501.105(A) which mentions having explosion proof, purged or pressurized.
Thanks in advance...
Yogi