Intrinsic Circuit Receptacle and Plug

[cleeton]

Can I install receptacles that contain only intrinsically safe circuit conductors in a Class 1, Div 1 Area for connection to a cart that has buttons and switches on it. The cart will be moved between a number of similar machines for one step in the process so the plug on the cart will be inserted and removed from the receptacles regularly, and likely while the environment contains explosive vapors.

 

[jaywillnot]

I'm not sure intrinsically safe circuitry is meant to be energized multiple times, and I'm certainly not the one to answer this question but maybe this link will help.

Good luck, and please be safe!http://www.parrinst.com/wp-content/uploads/downloads/2011/06/Svacina-Larson_Understanding-Hazardous-Area-Sensing_Intrinsic-Safety.pdf

 

[DLMUK]

Can I install receptacles that contain only intrinsically safe circuit conductors in a Class 1, Div 1 Area for connection to a cart that has buttons and switches on it. The cart will be moved between a number of similar machines for one step in the process so the plug on the cart will be inserted and removed from the receptacles regularly, and likely while the environment contains explosive vapors.

I'm not 100% sure what your asking here... can you provide more info?

anything you connect in the haz. area must be certified for use in that area. If the equipment doesn't have the correct markings for your zone, you cannot use it.

ia = 0
ib = 1
ic = 2

Switches and buttons can often be classed as 'simple apparatus' which removes the need for approvals - but you would need to look into your individual setup to confirm this.

Intrinsic safety is about current/power limiting so its all to do with the power and current requirements of your circuit.

 

[James Mcquade]

cleeton,

I would say no.
Read NEC 70, the 500's section deals with hazardous location wiring.
The principal of the hazardous wiring method is to isolate the non-hazardous wiring from the hazardous environment, which you will not be doing. Even though the wiring is using a barrier, you have exposed wiring at the connection.
Intrinsically safe wiring is a method of wiring such that in the event of a short in the wiring or damage to a device, the voltage and current is not sufficient
enough to create an electrical spark which could ignite the work environment.
As far as I know, it does not say what you are proposing is an approved wiring method. Also, the continuous connecting the devices to the intrinsic barrier can itself damage the barrier and thus create a an unsafe environment.

IN my opinion, you to get with safety and management to do a risk analysis and then you need a PE to look at the proposed system and put his stamp on it.

regards,
james

 

[cleeton]

See page K7 of this document from Turck, it looks like they feel it is safe to have quick disconnect cordsets on intrinsically safe wiring.

https://stevenengineering.com/Tech_Support/PDFs/46PA_PROCESS-WIRING.pdf

Questions I have outstanding still after reading NEC article 504 about a dozen times:
Would I need to have a control drawing (NEC 504.10(A))that included the plug and receptacle (turck has these for their cabling system but I'm looking for something more heavy duty) or would that just be part of the standard wiring methods allowed by 504.20?
Would the plug and receptacle need to comply with 504.30(B) for spacing of terminals? would I need to find a plug with at least 0.25" of clearance between pins?

All of the end equipment will be either simple apparatus (switches), or FM approved IS equipment.

Thanks for your responses so far.

 

[Bullzi]

I work in the Oil Industry and we sell a device used to keep trucks from overfilling. It uses I.S. circuits on the cable and plug that connects to the trucks. They have a plug and cable set that uses a Plug on the end that connects to the controller. This is designed to pull out if a truck drives off with the cable attached to the truck. It saves all the damage caused by a pull away situation when it is hard wired into the controller.

The system is designed for Class 1 Div 1 locations so if they can use a plug on the connection for both ends I don't see why you cant do the same. The fact that the circuit is I.S. means that the energy in the circuit is low enough not to cause a spark or ignition of hazardous atmospheres.

Just my opinion.

 

[cleeton]

Bullzi,
That sounds exactly like what I'm looking for. Sent you a PM with contact info. I'd love to get some details and a quote if possible.

Thanks