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Explosion Proof Flexible Conduit????

Explosion Proof Flexible Conduit????

Explosion Proof Flexible Conduit????

In a class 1 div. 2 group d area...

a wire leaves a control room and into the hazardous area 30' and then to an 8' long flame detection device...

This is the first time I've had to deal with this stuff and of course they want some kind of quote today...

my idea was to find 30' of some sealed flexible conduit (they need the line to be flexible)... not sure if it has to be explosion proof conduit or what... then put an explosion proof seal fitting on each end to seal it... then have the 8' long flame rod (just a flame sensing device in an 8' long tube) sealed on the other side of the one fitting on the flexible hose... then have another fitting within 18" from the end of the flame rod...

These are my original thoughts from what I could gather online for what is needed for this type of hazardous area...

I would really appreciate any guidance... I told my boss I needed a copy of the NEC about 1.5 mo ago... still havent seen it.... any help is much appreciated!

RE: Explosion Proof Flexible Conduit????


. I told my boss I needed a copy of the NEC about 1.5 mo ago... still haven't seen it....
It takes 2-3 days for NEC book to arrive. Order the book yourself and put it on expense report.
Also let sparkies deal with electrical engineering.

Rafiq Bulsara

RE: Explosion Proof Flexible Conduit????

Unfortunately he wanted to purchase this and another code book himself... so he's taking his good old time... I will look into purchasing myself tomorrow, but I hope someone might be able to give me a little info in the mean time... at least if I'm way off or on the right track or whatever.

I would like to let sparkies deal with EE stuff, but I'm as close to an EE that my company has... since I am the whole engineering dept... I just got this job about 2 months ago... so I'm going to have to learn to wear many hats here

RE: Explosion Proof Flexible Conduit????


since I am the whole engineering dept...

I understand your position and appreciate your candidness. The correct solution for your company is to hire an EE or a consultant. This site is for professionals. While someone may occasionally answer your questions, it may do more harm than good to you, if you do not understand full implication of one explanation.

You will also do well to buy the NEC Handbook that has some explanatory materials and pictures to better understand the code.

Rafiq Bulsara

RE: Explosion Proof Flexible Conduit????

Although it may be too late, consider searching for the draft 2011 NEC as a free download.  These should be available until the code update is approved.  I too like the NEC Handbook.

I have not looked at your application.  Consider straight conduit with flex at the end.  Even 30-inches is long for flexible conduit in classified areas.  Sealtight is a term for flexible conduit in Division 2 areas and usually limited below 18-inches.  Braided flexible conduit is available for Division 1 areas.  If you cannot buy a copy of the NEC then your budget is several orders of magnitude below the cost of braided flexible Div. 1 conduit.


RE: Explosion Proof Flexible Conduit????

I recommend you find out the contractor that installed the electrical in the 1D2 area (or the contractor that made the last improvement/change) and contact them for a quote.  Do a walk-thru with them and explain what you want.  Be sure to explain the different classified and non-classified areas the conduit travels through.  At the walk-thru, have all the specs and cut sheets available for the equipment that is on the circuit.  More than likely, they can handle it.  If they need an EE, they probably have one on staff.

Good luck,

RE: Explosion Proof Flexible Conduit????

This is Appeltons Code Digest.
Lots of information and it's free


Appelton has the same type book but you have to get it from a vendor rep (if they still make it) There is basic info and a tutorial on Appetons web site but no PDF of the Code Digest.
This is close

RE: Explosion Proof Flexible Conduit????

You can view the complete 2008 NEC (and other earlier revisions) on nfpa.org:

It's free, it will cost you nothing more than an email address.  Hazardours installations are covered in Articles 500-510 or so.

It may also be worthwhile for you to learn about "intrinsically safe" installations and see if that term applies to your installation.

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