Posted 21 Jan 2015 I have a question regarding hazardous zone design. My control cabinet will be in safe area but I need to have e-stop and safety limit switch located in hazardous area, Div 1 Zone 1. I am assuming that I can use zener barriers or isolators between the field devices and safety relay. I just wonder if the safety relay will function properly with barriers in between? Also do I have to use 24VDC safety relay for this application? I don't know what voltage/current is present on the terminals connecting to safety devices. Share this post Link to post Share on other sites
Posted 22 Jan 2015 If you use a conduit listed in NEC Article 501 and the E-Stop housing is listed for hazardous locations, then you can take the 24vdc (or 120vac) straight to the device. Another way: you can use an intrinsically safe barrier inside your enclosure, and take the IS wiring to your E-Stop. Doing this will not affect the E-Stop Sensitivity Relay at all. Just make sure you use N/C monitored contacts on your E-Stop, a N/O contact on your IS Barrier (which will be energized under regular conditions thus making the contact close) and the standard SIL 2/3 wiring diagrams on the E-Stop relay. I recommend Phoenix Contact P/N 2865434 for the IS Barrier. Share this post Link to post Share on other sites
Posted 23 Jan 2015 After pricing some explosion proof operator consoles I think I will be much better off just using intrinsically safe barriers. Do I have to run intrinsically safe wiring in separate conduit separate from the other wiring? And should the conduit be blue? Share this post Link to post Share on other sites
Posted 23 Jan 2015 Yes, all IS wiring shall be no less than 2 inches from non IS wiring. The conduit does not need to be blue, but identifiers within the panel should be. I.e. Terminal Blocks, wiring, and wire-way. Share this post Link to post Share on other sites
Posted 23 Jan 2015 Thanks for the great info. I really appreciate you took time to help me out. Share this post Link to post Share on other sites
Posted 23 Jan 2015 No problem, glad I could help. Good luck!!! Share this post Link to post Share on other sites
Posted 29 Jan 2015 (edited) I don't know what you're looking for when you say "explosion proof operator console", but it sounds expensive. Aren't you just looking for a single E-Stop button? You can just get a regular explosion proof box with an E-Stop button (like this). Then make sure you either have a conduit seal or a sealed Tek connector (STX) if you are using Tek Cable. I'm not saying it's better or worse, but then you don't have to create a physically isolated part of your cabinet for intrinsically safe installations, and a dedicated intrinsically safe conduit/cable tray, and all that stuff that comes along with intrinsically safe installations. Edited 29 Jan 2015 by MrAutomation Share this post Link to post Share on other sites
Posted 27 Jan 2022 I have another question regarding this; We have E-Stops in the classified area, wired back to barriers in the control panel( outside the classified area) and from the barriers to a (Red) Safety Relay in the control panel. Do the barriers have to be (Red) Safety barriers also? Thank You Share this post Link to post Share on other sites