Type TC CI DivII

[DonaldSparkyDog]

We are working in a bio diesel plant that uses methanol in the process. The owners have declared the classified area to be from the floor up to 4'. They have requested a feeder in cable tray from the switchgear to a heater control panel that will be purged with plant air with an interlocking alarm in case of pressure drop. The cable tray is 10' above the floor but the bottom of the control panel is within the classified area. I plan on the TC to drop down from overhead into an IMC conduit nipple with a seal off at the cabinet and seperating the cables when I pour the seal instead of using a harzardous location cable terminating fitting. Has anyone done this before in this kind of location?

 

[weressl]

We are working in a bio diesel plant that uses methanol in the process. The owners have declared the classified area to be from the floor up to 4'. They have requested a feeder in cable tray from the switchgear to a heater control panel that will be purged with plant air with an interlocking alarm in case of pressure drop. The cable tray is 10' above the floor but the bottom of the control panel is within the classified area. I plan on the TC to drop down from overhead into an IMC conduit nipple with a seal off at the cabinet and seperating the cables when I pour the seal instead of using a harzardous location cable terminating fitting. Has anyone done this before in this kind of location?

A simple cable drop in tray/channel is sufficient, there is no need for conduit. Use a CGB to terminate the cable to the cabinet and it will sufficiently seal the cable not to loose to much of the purging air, your only concern. If you want to be extra conservative then inject caulk sealant in the interstices of the conductors on the inside of the purged cabinet where the jacket is terminated.

The 4' area above the floor is Class I, Div. 2 and you are using NFPA 496 Class Z purging, correct?

 

[DonaldSparkyDog]

Thanks for the reply. The controls contractor is doing all the power and instrument cabinet wiring for the skids with branch wiring to motors and heaters, we will provide feeder circuits to a single point connection on fbo panel mounted disconnect switches. They have indicated there will be purging but I am not aware of which class.

 

[weressl]

Thanks for the reply. The controls contractor is doing all the power and instrument cabinet wiring for the skids with branch wiring to motors and heaters, we will provide feeder circuits to a single point connection on fbo panel mounted disconnect switches. They have indicated there will be purging but I am not aware of which class.

I think you should request a formal area classification documentation befoe you proceed with your installation.

 

[DonaldSparkyDog]

OK I will, but what does a "formal" document look like? I suppose a transmittal letter with the formal document would cma.

 

[RFI]

You should be looking for an area classification plan. It will detail out where areas are classified.

 

[rbalex]

OK I will, but what does a "formal" document look like? I suppose a transmittal letter with the formal document would cma.

Section 500.4(A) requires proper documentation. Both NFPA 497 and API RP-500 have appendices/annexes that outline the proper procedures for classifying and documenting.

 

[DonaldSparkyDog]

Thanks for the reply. I have notified management and will await an answer.