Intrinsic Safe Wiring to Instrument 2

[valvepuke]

I have a Westlock Quantum 3600 Series position switch box with pneumatic solenoid fitted to it. It is mounted to a ball valve actuator. This assembly is certified to ATEX EEx"i", instrinsically safe. Problem is that the box has only one cable entry hub. We have two cables routed to this unit, one with 24 VDC solenoid control and the other for the status output from the switches, also 24 VDC. CablesCan I add a standard conduit fitting such as a Crouse Hinds GUAT, nipple mounted to the existing hub on the Westlock, fit both cable ends to the two other hubs on the fitting and pigtail the wires into the Westlock? I do not want to change out the Westlock and I cannot rewire the site to bring both control and status in one cable. I just need to physically be able to create two cable entries from one.

 

[roydm]

I gather that the switches and solenoid are all intrinsic safe, are the signals as well? You cannot mix IS and Non IS wiring (in NA anyway).
If it's not a hazardous location no problem, just use a tee or small box to combine 2 cables into 1
Roy

 

[valvepuke]

Roy, Thanks for the prompt response. The area is hazardous, and the components, solenoid valve and limit switches, are all I.S. The GUAT would be a standard NEMA 7 box but I don't think that comes into play for I.S. construction; just mostly a robust electrical component.

 

[ilan7]

Valvepuke
If all items (S.V and switches) are IS, do not see any problem. You have to add the IS berriers (as per approved valve manufacturer IS drawinds) somewhere outside the Hazardous area, Run the cables from there with no Junction boxes or with J.B's with only IS equipment connected there, and enter into the valve with one multi-core cable or two cables entering a small box at the valve cable entry.

 

[roydm]

As iIan7 says, a small box or a conduit Tee since there are no terminations required (the wires go straight to the Westlock).
Another way would be to mount a small NEMA 4 box adjacent to the valve then run both cables through a length of 1/2" flexible conduit. That makes it easier to remove and makes for a neat installation. Coil up some spare wire in the box. Leave the inner jacket in place to prevent the shield touching ground.
If you need vapour seals to prevent gas migrating to the safe area they can be between the cables and box.
I don't believe you need NEMA 7 in this case (non sparking or intrinsic safe)
Roy

 

[JLSeagull]

Don't forget the marking. Few US projects are IS although some aspects such as the thermostat in an analyzer shelter may require barriers. Assure that you include the required labels, special colors etc. to identify intrinsically safe circuits and segregate from all other conductors.

 

[itsmoked]

I too agree that if the 24V stuff has come thru a barrier you can punch more holes in you box with no issues. You could use a non-sparking hatchet to do it even. The safety is in the 'intrinsic' not the enclosures.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Standingback]

IS by definition stated that the components within the enclosure do not store enough energy to cause ignition. Adding extra cable entries does not effect the IS rating.

I trust this helps,
Mlv

http://www.coulton.com

 

[JimCasey]

If Westlock put the I.S. label on it and shipped it with the solenoid attached, and particularly if the solenoid is called out in the model code, then the whole thing is I.S.
May need to be wired through approved barriers in a nonhazardous environment, but like Standingback says:no component stores energy.

Consult your owner's manual, or download one from Westlock's website.