501.15

[AKsparky1]

I have a sump pump room that the engineer has classified as cl I div II. The state or anybody else does not consider this room classified at all but it doesn't matter because we are building it to what the engineer wants. My question is am I required to provide a seal at the point of entrance to a explosion proof incandescent light fixture that has MCHL (cable requrement) as a wiring method which originates outside the classified area and is sealed within 10ft of this bounry in a gutter outside the classified area. I do not have my code book infront of me but when I looked it up I believe it said that cable must be sealed at an eclosure that is explosion proof rated at the point of entrance. The cable is actually less then ten feet from where it enters the classified area to where it terminates at the fixture so it was done with a seal at the boundry only and not at the fixture. I think that if I sealed it at the fixture only I would have satisfied two requrements since the length of the cable is less then ten feet. What do you think? Do I need a TMCX connector at the fixture in addition to seal at the boundry?

Also is there any requirement that says a TMCX connector cannot be consealed in a wall space? No one will ever know it is there except the inspector that saw us install it. Thank you.

 

[rbalex]

A TMCX at the luminaire was all that was necessary; a boundary seal wasn't needed.

Was the concealed TMCX terminated in an accessible enclosure?

 

[weressl]

A TMCX at the luminaire was all that was necessary; a boundary seal wasn't needed.

Was the concealed TMCX terminated in an accessible enclosure?

Even though the area is Cl. I, Div 2. the fixture may required to be rated Class I, Div. 1 because the wattage size does not offer one with the corresponding T-rating on the Div. 2 selection. In that case the fixture will require a seal, because its T rating is only for the OUTSIDE surface envelope, while a Div. 2 rating is anywhere on the fixture.

 

[rbalex]

Even though the area is Cl. I, Div 2. the fixture may required to be rated Class I, Div. 1 because the wattage size does not offer one with the corresponding T-rating on the Div. 2 selection. In that case the fixture will require a seal, because its T rating is only for the OUTSIDE surface envelope, while a Div. 2 rating is anywhere on the fixture.

I have no argument with your statement. However, the OP already stated the luminaire was explosionproof. Whether it was necessary or not was neither relevant to the question asked nor to the answer. The only necessary seal was at the luminaire and nothing was needed at the boundary.

 

[weressl]

I have no argument with your statement. However, the OP already stated the luminaire was explosionproof. Whether it was necessary or not was neither relevant to the question asked nor to the answer. The only necessary seal was at the luminaire and nothing was needed at the boundary.

Sorry, not realized that TMCX is an XP seal, I though it was just a cable terminator.

 

[rbalex]

Sorry, not realized that TMCX is an XP seal, I though it was just a cable terminator.

Your earlier response made me rethink a few things last night.

Whether the luminaires are identified for either Division 1 [Section 501.130(A)] or Division 2 [Section 501.130(B)], the most likely configuration is a factory seal between the main enclosure compartment and the terminal housing. If so, there is no other seal required at all either at the luminaire [Section 501.15(E)(1)] since the terminal housing would no longer be required to be explosionproof OR at the boundary under Section 501.15(E)(3).

NOTE: UL identifies both MC-HL and TC as "Cables Capable of Transmitting Gases or Vapors". They are only required to be sealed under Section 501.15(E)(1). That requirement would be eliminated by a factory seal in Division 2.


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If there is no factory seal in the enclosure, then a TMCX at the enclosure is still all that would be required; still no boundary seal.

 

[weressl]

Your earlier response made me rethink a few things last night.

Whether the luminaires are identified for either Division 1 [Section 501.130(A)] or Division 2 [Section 501.130(B)], the most likely configuration is a factory seal between the main enclosure compartment and the terminal housing. If so, there is no other seal required at all either at the luminaire [Section 501.15(E)(1)] since the terminal housing would no longer be required to be explosionproof OR at the boundary under Section 501.15(E)(3).

NOTE: UL identifies both MC-HL and TC as "Cables Capable of Transmitting Gases or Vapors". They are only required to be sealed under Section 501.15(E)(1). That requirement would be eliminated by a factory seal in Division 2.


​

If there is no factory seal in the enclosure, then a TMCX at the enclosure is still all that would be required; still no boundary seal.

Crouse-Hinds EVM fixture instructions:

Note;
For Group B applications seal all conduits per NECection 501.5(A) (CEC Section 18-108).

 

[Smart $]

Crouse-Hinds EVM fixture instructions:

Note;
For Group B applications seal all conduits per NECection 501.5(A) (CEC Section 18-108).

MCHL is not a conduit.

Pertinent section(s)...

(E) Cable Seals, Class I, Division 2. In Class I, Division 2
locations, cable seals shall be located in accordance with
501.15(E)(1) through (E)(4).

(1) Terminations. Cables entering enclosures that are required
to be explosionproof shall be sealed at the point of
entrance. The sealing fitting shall comply with 501.15(B)(1).
Multiconductor cables with a gas/vaportight continuous sheath
capable of transmitting gases or vapors through the cable core
shall be sealed in a listed fitting in the Division 2 location after
removing the jacket and any other coverings so that the sealing
compound surrounds each individual insulated conductor
in such a manner as to minimize the passage of gases and
vapors. Multiconductor cables in conduit shall be sealed as
described in 501.15(D).

Exception No. 1: Cables passing from an enclosure or
room that is unclassified as a result of Type Z pressurization
into a Class I, Division 2 location shall not require a
seal at the boundary.

Exception No. 2: Shielded cables and twisted pair cables
shall not require the removal of the shielding material or
separation of the twisted pairs, provided the termination is by
an approved means to minimize the entrance of gases or vapors
and prevent propagation of flame into the cable core.

...

(3) Cables Capable of Transmitting Gases or Vapors.
Cables with a gas/vaportight continuous sheath capable of
transmitting gases or vapors through the cable core shall not
be required to be sealed except as required in 501.15(E)(1),
unless the cable is attached to process equipment or devices
that may cause a pressure in excess of 1500 pascals (6 in. of
water) to be exerted at a cable end, in which case a seal,
barrier, or other means shall be provided to prevent migration
of flammables into an unclassified location.

Exception: Cables with an unbroken gas/vaportight continuous
sheath shall be permitted to pass through a Class I,
Division 2 location without seals.

(4) Boxes and Fittings. Boxes and fittings shall not be
required to be explosionproof except as required by
501.105(B)(1), 501.115(B)(1), and 501.150(B)(1).

 

[rbalex]

MCHL is not a conduit.

Pertinent section(s)...

No and it's not 501.5 anymore either and hasn't been since 2002; it's Section 501.15 now. Nevertheless, the principal would be the same for the cables with this luminaire in Division 1. That said, we have no reason to believe it is in Group B in the first place. EDIT ADD: In fact, the OP said it shouldn't have been classified at all.

I'm only trying to address the OP, not every speculation out there. A boundary seal was never necessary and wouldn't be adequate for the luminaire no matter what the Group. The necessity of a seal at the luminaire is dependent on the presence or absence of a factory seal.

 

[Smart $]

No and it's not 501.5 anymore either and hasn't been since 2002; it's Section 501.15 now. ...

I think you quoted the wrong post. My post quotes 501.15. It's Laszlo's post that mentions 501.5.

ETA: unless by "No" you were agreeing with me that MCHL is not a conduit

 

[weressl]

No and it's not 501.5 anymore either and hasn't been since 2002; it's Section 501.15 now. Nevertheless, the principal would be the same for the cables with this luminaire in Division 1. That said, we have no reason to believe it is in Group B in the first place. EDIT ADD: In fact, the OP said it shouldn't have been classified at all.

I'm only trying to address the OP, not every speculation out there. A boundary seal was never necessary and wouldn't be adequate for the luminaire no matter what the Group. The necessity of a seal at the luminaire is dependent on the presence or absence of a factory seal.

To cut to the chase, what I was stipulating that in SOME cases the fixture may need to be sealed XP, eg. any openings and any connections need to maintain the internal explosion withstand rating be it a conduit or a special cable connector. I think the C-H instructions demonstrate that, so there is no reason why blanket statement can not be made weather a fixture needs to be sealed off or not without reading the installation instructions. Here we can clearly see the fallacy and repercussions of paragraph changing of the Code, the manufacturer will not revise it because they would need to resubmit to UL for approval. When the original approval was given, some of the cables now specifically called out in the NEC did not even exist. Does that mean that you can not use them on this specific fixture because they are not listed/tested in the instructions? Don't think so.

I never said anything about boundary seal need, had no disagreement with what was stated.