Class I, Division 2

[mshields]

In perusing Article 501, it would appear that for an area with nothing more fancy that lights and receptacles, the only special requirement is for seals on both sides of the walls defining the classified area. What's more the conduit could actually be MC.

So you agree that this is so.

Also, I see a picture in the handbook utilizing MC

 

[rbalex]

Peruse is an interesting term. It has two definitions that are diametrically opposed. From the Webster’s Collegiate Dictionary, 11th edition:

1a : to examine or consider with attention and in detail : study
b : to look over or through in a casual or cursory manner

It appears you are using 1 b.

I mentioned in your previous post that you weren't careful enough. That still appears to be true.

Assuming the location is properly classified, I suggest you consider the following Sections more carefully:

• 501.130(B)
• 50​1.145 [NOTE: The requirements for Division 1 and 2 are identical].

You can indeed use Type MC but, since you are misapplying Sections 501.15 (B) (1) and (2), which part of Section 501.15(E) do you intend to use?

[NOTE: While "common" Type MC may be used in Division 2, it will be a NIGHTMARE to seal at the boundary.]​
​

I also suggest giving Section 500.8 a careful examination.

 

[rbalex]

Corrected references in previous post. Thanks Augie:thumbsup:

 

[petersonra]

[NOTE: While "common" Type MC may be used in Division 2, it will be a NIGHTMARE to seal at the boundary.]​

I have heard it suggested elsewhere that one could use closed cell foam from a can to make this kind of seal since it is not required to be listed.

 

[rbalex]

I have heard it suggested elsewhere that one could use closed cell foam from a can to make this kind of seal since it is not required to be listed.

You didn't hear it suggested by me . Interlocked armor Type MC falls under Section 501.15(E)(4). Trust me; listed or not, sealing it properly anywhere other than the termination(s), even with "... closed cell foam from a can ...", is incredibly difficult to show it meets the requirements.

 

[mshields]

thank you

thank you

much appreciated

 

[GoldDigger]

Is part of that problem that you cannot control infiltration of gas into the armor on one side of the plug and out on the other?
If so, would making the seal in a jbox in the boundary wall where two sections of cable are spliced together be practical? Or would that require listed fittings too?

 

[rbalex]

Is part of that problem that you cannot control infiltration of gas into the armor on one side of the plug and out on the other?
If so, would making the seal in a jbox in the boundary wall where two sections of cable are spliced together be practical? Or would that require listed fittings too?

You have correctly identified the problem and a potential solution. Practicality, may be debatable.

A better solution would be to use Type MC with a "corrugated metallic sheath". This is not necessarily Type MC-HL, although it could be.

In my opinion, an even better solution would be a properly installed Type TC or TC-ER wiring method.

In either case, "corrugated metallic sheath" Type MC or Type TC sealing fall under Sections 501.15(E)(1) and (3). Depending on the NEC edition, it may be necessary to parse Section 501.15(E)(1) VERY carefully, but neither "corrugated metallic sheath" Type MC nor Type TC requires a boundary seal. (It is my understanding that ISA has submitted Public Input for the 2017 NEC to reduce the parsing necessary.)