yanivk
Member
- Location
- Charlotte NC USA
- Occupation
- Controls Engineering Manager
Hi!
I am quoting a job where the customer wants us to install several sliding guard doors in a Class1 Div1 area and monitor if they are not closed. I have selected a non-contact safety proximity sensor to monitor each guard door. The sensor is fully encapsulated and rated for use in ATEX Zone 0. It has 2 N.C. + 1 N.O. dry contacts. No control power required. Customer has approved the use of this sensor in their C1D1 area and is responsible for any risk assessment and validation. The sensor comes factory-installed with a 10m long stainless steel flexible conduit (not sure of conduit size) to protect the flying-lead multiconductor cable. I am planning to terminate 4 such sensors into a junction box using the supplied flex conduits and run a single rigid metal conduit with single seal-off back to the PLC panel in un-classified area that's 150ft away from this junction box, where I will monitor these sensors using safety relays.
My questions are:
- Does this junction box need to be NEMA7 rated? Even though there are no arcing devices in the JB and the sensors are Zone0 rated.
- Do I need a seal-off on each sensor conduit? If so, do I need to replace the flex conduit that comes with the sensor with rigid metal conduit?
My alternate solution is to use general-area rated non-contact safety prox sensors and run each dry-contact signal through a P&F switch amplifier that will be installed in the PLC panel. Thus eliminating the electrical thermal energy to cause a spark. Is this a viable solution?
Can I simply run the sensor's M12-to-flying lead multiconductor cordsets directly into a regular junction box using cord grips? Single RMC with seal-off back to the PLC panel.
This alternate solution will make the job significantly easier, quicker and cheaper.
I am here to learn and open to all suggestions.
Thank you.
Big fan of this forum.
I am quoting a job where the customer wants us to install several sliding guard doors in a Class1 Div1 area and monitor if they are not closed. I have selected a non-contact safety proximity sensor to monitor each guard door. The sensor is fully encapsulated and rated for use in ATEX Zone 0. It has 2 N.C. + 1 N.O. dry contacts. No control power required. Customer has approved the use of this sensor in their C1D1 area and is responsible for any risk assessment and validation. The sensor comes factory-installed with a 10m long stainless steel flexible conduit (not sure of conduit size) to protect the flying-lead multiconductor cable. I am planning to terminate 4 such sensors into a junction box using the supplied flex conduits and run a single rigid metal conduit with single seal-off back to the PLC panel in un-classified area that's 150ft away from this junction box, where I will monitor these sensors using safety relays.
My questions are:
- Does this junction box need to be NEMA7 rated? Even though there are no arcing devices in the JB and the sensors are Zone0 rated.
- Do I need a seal-off on each sensor conduit? If so, do I need to replace the flex conduit that comes with the sensor with rigid metal conduit?
My alternate solution is to use general-area rated non-contact safety prox sensors and run each dry-contact signal through a P&F switch amplifier that will be installed in the PLC panel. Thus eliminating the electrical thermal energy to cause a spark. Is this a viable solution?
Can I simply run the sensor's M12-to-flying lead multiconductor cordsets directly into a regular junction box using cord grips? Single RMC with seal-off back to the PLC panel.
This alternate solution will make the job significantly easier, quicker and cheaper.
I am here to learn and open to all suggestions.
Thank you.
Big fan of this forum.
