Cable Conduit Requirement

It depends on the rating of the area.....such as mission critical shut down of equipment and fire safety requirements.....the materials being handled or processed will determine the area classification, then you need equipment that is rated for that classification....

http://en.wikipedia.org/wiki/Electrical_equipment_in_hazardous_areas

As plastics go PVC has a high ignition temperature at 455°C.

May concerns would be whats in the pipe and what it feeds to. As safety equipment in the event of a fire.

There are pan-European and pan-North-American standards for the installation of electrical equipment in potentially explosive atmospheres. These standards are similar, though not the same, and the underlying principle behind the various techniques available is that the risks of the electrical installation causing fire or explosion are minutely low through the correct design, selection, installation and maintenance of the installation by correctly-trained persons.

If the correct training is not on board, stop work and delegate the task to someone who is correctly trained. The safety of the installation and everyone who works and lives on or near it depends upon taking this action.

Virtually all commercial wire and conduit meet a minimum fire tolerance.

This does not mean that a PVC conduit and the wiring contained inside will withstand all fires indefinitely.

You are implying that the tanks contain flammable liquids.

If true, your conduit must comply with article 500 of the NEC if you are in the USA.

This may require rigid steel conduit and explosion proof fittings, seal-offs, etc.

Thank you. I am in North America. Thanks for leading me to NFPA 70. The tank carries flammable hydrocarbon. My concern is if there is a fire in the dike, I want the cable conduit to withstand the fire to allow for proper shutdown of the facility.

If you want/need the electrical installation to continue working in the event of a fire then you will be needing mineral insulated conductors eg pyrotenax.

If it is just mechanical protection that is required then steel conduit may be stipulated for hazardous areas.

If the PVC conduit doesn't catch fire is certainly will be deformed, sag and perhaps even encapsulate the wires within it. Heating PVC pipe/conduit is the most frequently used method of bending it into other than straight runs. This is done at temperatures less than fire conditions.

Another concern would be the insulation of the wire within the conduit. Normally used wire THHN, THWN and others have insulation that will not withstand the heat that would be generated within the PVC conduit. As the insulation breaks down the wire within the insulation would contact each other and possibly short or break. Either way the wires would be worthless and you would have no control of the circuits.

NFPA 70 is more readily available and cheaper if you get a copy of the National Electrical Code (NEC), they are the same. NFPA 70 is part of the whole NFPA codes at about $1,500 and the NEC is about $40-50.

Good Luck, Old Salt

The first thing you need to do is determine your area classification. If you are in (likely) a Class 1 Div 2 then you will need to follow the specifications required for the area. How "fire retardant" the conduit is really isn't the question; you need to know if it is rated for the area and materials being stored.

Your best bet is to pull the classification drawings for your area and this will define your requirements.

Rick

Rick, Thank you very much for your response. The conduit is sealed so there is no flammable vapor ingress into the conduit. My understanding is that this should be sufficient from an EAC perspective. The concern is that if there is a fire in the tank dike, then I need the conduit to withstand the fire for some time to enable proper facility shutdown. Area calssification is not an issue for the problem at hand. My concern is the effect of an external fire on a PVC conduit.

refer to #6