300.3 (C)(1) - Bundling flexible cords for heater at Hazardous Area Class 1 Div 2

[lmhyd2013]

Hi,

I am trying to figure out alternative way to power multizone heating in hazardous area Class 1 Div 2 involving hydrogen gas. One of the solution was to use flexible custom made multicore cable as there are 5 three phase circuits to energize. The cost of this solution was too high and upon reading 300.3(C)(1), I believe it would be alright to bundle / sleeve single cores altogether.

Conductors of circuits rated 600 volts, nominal, or less, ac circuits, and dc circuits shall be permitted to occupy the same equipment wiring enclosure, cable, or raceway. All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway.

The problem is NEC does not specify what appropriate way to do it. I don't see any restriction in article 500 and 501.

Any help would be appreciated.

L

 

[rbalex]

Try rereading Section 501.10(B). You are only permitted to use one of the wiring methods listed there. The method you have described is not one of them.

 

[lmhyd2013]

Hi Bob,

I based the wiring method with flexible connections from 501.10 (B)(2), it says that flexible connections are allowed in 501.10 (B)(2) as long as the flexible cord satisfies one of the requirements. In my case 501.10(B)(2)(5)

Flexible cord listed for extra-hard usage and terminated
with listed fittings. A conductor for use as an equipment
grounding conductor shall be included in the flexible cord.

and also from 501.140(A)(2)

For that portion of the circuit where the fixed wiring
methods of 501.10(A) cannot provide the necessary degree
of movement for fixed and mobile electrical utilization
equipment, and the flexible cord is protected by location
or by a suitable guard from damage and only in an
industrial establishment where conditions of maintenance
and engineering supervision ensure that only qualified
persons install and service the installation.

Did I understand the clauses incorrectly?

 

[rbalex]

Is yours an application "Where provision must be made for limited flexibility ..." [see Section 502.10(B)(2) main text]? The OP did not give the impression that "limited flexibility" was essential.

 

[lmhyd2013]

Thanks for your reply, Bob.

Did you mean 501.10(B)(2) as 502.10(B)(2) is for Class 2 Division 2?

Well, 501.10(B)(1)(1) stated that all wiring methods permitted in 501.10(A) shall be permitted, and 501.10(A)(2) stated flexible cord in accordance with the provisions of 501.140 terminated with cord connectors listed for the location shall be permitted where it is necessary to employ flexible connections. NEC did not specify the specific meaning of "limited flexibility", so from 501.10(A)(2) I deduce that the limitations are listed in 501.140.

Those clauses permits the usage of flexible cords with the listed requirements in 501.140(B) unless I still have some flaws in putting the clauses altogether.

Say, the flexible cords are permitted, in accordance to 300.3(C)(1) what kind of methods to put together the flexible cords are permitted?

Regards,
Levin

 

[rbalex]

Yes, I meant 501.10(B)(2). In any case, even with the back reference to 501.10(A), you must establish the need for flexibility.

 

[lmhyd2013]

Bob,

The utilization equipment should be portable and removable when required. So does that establish the need for flexible connection?

If yes, what practice usually done when bundling the single core flexible cords altogether?

L

 

[rbalex]

Then your reference to Section 501.140 is proper. But remember, there is more to it than that. You will need to be in accord with all applicable Subsections in 501.140 (A) and (B).

In addition, you need to review compliance with Sections 501.30 and 501.145.

If we get much past this I start charging consulting fees since I would need much more ?on-hands? knowledge of the installation and its application.