Cable Seals 501.15(E)

[Dale001289]

Just need a sanity check to make sure the following statements are true:
· TC-ER control cable (non-shielded) terminates in factory-sealed 'Start-Stop' PB station –
No cable seal required based on 501.15(E)(1) and 501.15(E)(3), i.e. may use C-H, CGB, TMC or equal fitting for termination.

· MC-HL control cable (non-shielded) terminates in NON-Factory-sealed 'Start-Stop' PB station – Cable seal required based on501.15(E)(1) and 501.15(E)(2), i.e. must use C-H, TMCX or equal fitting for termination.
LNG plant, Class I, Division 2 Gps C&D

 

[rbalex]

This is one case where knowing which edition of the NEC you are using would be very helpful. Section 501.15(E) and its Subsections got muddled in 2014. Careful parsing of 501.15(E)(1) is extremely important to interpret the other Subsections correctly.

That said, Subsection 501.15(E)(3) is useless in any recent edition. It doesn't apply to cable except Type MI which already has its own installation requirements in Section 501.10(A)(1)(b). No manufacturer nor UL will certify any cable, except Type MI, as, "...incapable of transmitting gases or vapors through the cable core."

It is also important to understand that a factory sealed device's "seal" cannot do "double duty"; i.e., is does not seal the cable.

 

[Dale001289]

This is one case where knowing which edition of the NEC you are using would be very helpful. Section 501.15(E) and its Subsections got muddled in 2014. Careful parsing of 501.15(E)(1) is extremely important to interpret the other Subsections correctly.

That said, Subsection 501.15(E)(3) is useless in any recent edition. It doesn't apply to cable except Type MI which already has its own installation requirements in Section 501.10(A)(1)(b). No manufacturer nor UL will certify any cable, except Type MI, as, "...incapable of transmitting gases or vapors through the cable core."

It is also important to understand that a factory sealed device's "seal" cannot do "double duty"; i.e., is does not seal the cable.

Bob, I'm using the 2017 NEC Handbook. What I gather from your last sentence is that the cable still must be sealed even if the control station is factory sealed?

 

[rbalex]

Bob, I'm using the 2017 NEC Handbook. What I gather from your last sentence is that the cable still must be sealed even if the control station is factory sealed?

Definitely don't rely too heavily on the Handbook for classified locations.

But I'm shamefaced :ashamed1: too. It is Section 501.15(E)(2) that is useless rather than Section 501.15(E)(3) but still for the reasons I mentioned before; nothing but Type MI is recognized as restricting gases or vapors through the cable core.

Here's the deal with Section 501.15(E)(3). The 2017 NEC is much better than the 2014. (That not makes it a lot easier to understand) There is a general exemption from sealing cables with a gas/vaportight continuous sheath in Division 2 unless they are required to be sealed by Section 501.15(E)(1) OR are connected to process equipment or devices capable of exerting pressure on the cable end if the equipment or devices should leak. Section 501.17 deals with leak measures for process equipment. It's rather complex.

So - in your specific scenario, does Section 501.15(E)(1) require the cable to be sealed, recognizing that a factory seal for the control station doesn't seal the cable?. I would argue that the overall enclosure beyond the factory seal is no longer required to be explosionproof.

 

[Dale001289]

Definitely don't rely too heavily on the Handbook for classified locations.

But I'm shamefaced :ashamed1: too. It is Section 501.15(E)(2) that is useless rather than Section 501.15(E)(3) but still for the reasons I mentioned before; nothing but Type MI is recognized as restricting gases or vapors through the cable core.

Here's the deal with Section 501.15(E)(3). The 2017 NEC is much better than the 2014. (That not makes it a lot easier to understand) There is a general exemption from sealing cables with a gas/vaportight continuous sheath in Division 2 unless they are required to be sealed by Section 501.15(E)(1) OR are connected to process equipment or devices capable of exerting pressure on the cable end if the equipment or devices should leak. Section 501.17 deals with leak measures for process equipment. It's rather complex.

So - in your specific scenario, does Section 501.15(E)(1) require the cable to be sealed, recognizing that a factory seal for the control station doesn't seal the cable?. I would argue that the overall enclosure beyond the factory seal is no longer required to be explosionproof.

Thanks Bob for clarification on MI cable. I always thought cables with suffix "-HL", i.e. MC-HL, TC-ER-HL, etc had a core that prevented passage of hazardous vapors, since they are suitable for Division 1 locations.
Just to be sure, in conclusion: Since the factory sealed control station is not required to be explosionproof, the cable is therefore not required to be sealed per 501.15(E)(1)?

 

[Dale001289]

Thanks Bob for clarification on MI cable. I always thought cables with suffix "-HL", i.e. MC-HL, TC-ER-HL, etc had a core that prevented passage of hazardous vapors, since they are suitable for Division 1 locations.
Just to be sure, in conclusion: Since the factory sealed control station is not required to be explosionproof, the cable is therefore not required to be sealed per 501.15(E)(1)?

In the petro-chem field, we’ve always used MC-HL cable in Division 2. But, I cant see any real advantage over simple MC cable for Div 2 applications. Plus MC-HL costs much more. What am I missing?

 

[rbalex]

I was fairly heavily involved with the development of what became MC-HL; a bit less so with what became TC-ER. I will spare most of the details.

While I was a member of the API SOEE, I suggested and they endorsed and made a Proposal that cable with a gas/vaportight continuous corrugated aluminum sheath, an overall jacket of suitable polymeric material, separate equipment grounding conductors and suitable terminations be accepted in Class I, Division 1. Technically, this was a common form of one of the standard constructions for Type MC [Article 330, Part III in the 2014 NEC; Article 330, Part III in 2017] - until UL got a hold of it. I was one of the primary reviewers of UL's original proposed standard. If the cable were marked as UL originally proposed, it would take a minimum of 9' to accommodate all the text. They settled on "MC-HL" after my comments to that requirement.

There is nothing in the NEC nor UL Standards that require filling any "-HL" cable to prevent the transmitting of gases/vapors. In fact, it is still a basic "continuous corrugated aluminum" construction, only with a higher price.

With regard to TC-ER, I was a major proponent. Why anyone felt a need to append "-HL" is beyond me except to jack up the price. It is still the common construction but tested to meet the crush/impact test of Type MC - which most Type TC constructions pass.

It is important to note TC-ER-HL is only recognized for use in Division 1 as a "flexible connection"; i.e., it is "super duper" - extra-hard usage [See Section 501.140].

Last, but not least, yep, "Since the factory sealed control station is not required to be explosionproof [at the cable entry], the cable is therefore not required to be sealed per 501.15(E)(1) [and (3)]"

 

[Dale001289]

I was fairly heavily involved with the development of what became MC-HL; a bit less so with what became TC-ER. I will spare most of the details.

While I was a member of the API SOEE, I suggested and they endorsed and made a Proposal that cable with a gas/vaportight continuous corrugated aluminum sheath, an overall jacket of suitable polymeric material, separate equipment grounding conductors and suitable terminations be accepted in Class I, Division 1. Technically, this was a common form of one of the standard constructions for Type MC [Article 344, Part C in the 2014 NEC; Article 330, Part III in 2017] - until UL got a hold of it. I was one of the primary reviewers of UL's original proposed standard. If the cable were marked as UL originally proposed, it would take a minimum of 9' to accommodate all the text. They settled on "MC-HL" after my comments to that requirement.

There is nothing in the NEC nor UL Standards that require filling any "-HL" cable to prevent the transmitting of gases/vapors. In fact, it is still a basic "continuous corrugated aluminum" construction, only with a higher price.

With regard to TC-ER, I was a major proponent. Why anyone felt a need to append "-HL" is beyond me except to jack up the price. It is still the common construction but tested to meet the crush/impact test of Type MC - which most Type TC constructions pass.

It is important to note TC-ER-HL is only recognized for use in Division 1 as a "flexible connection"; i.e., it is "super duper" - extra-hard usage [See Section 501.140].

Last, but not least, yep, "Since the factory sealed control station is not required to be explosionproof [at the cable entry], the cable is therefore not required to be sealed per 501.15(E)(1) [and (3)]"

Thanks again Bob, great info.

 

[Dale001289]

I was fairly heavily involved with the development of what became MC-HL; a bit less so with what became TC-ER. I will spare most of the details.

While I was a member of the API SOEE, I suggested and they endorsed and made a Proposal that cable with a gas/vaportight continuous corrugated aluminum sheath, an overall jacket of suitable polymeric material, separate equipment grounding conductors and suitable terminations be accepted in Class I, Division 1. Technically, this was a common form of one of the standard constructions for Type MC [Article 344, Part C in the 2014 NEC; Article 330, Part III in 2017] - until UL got a hold of it. I was one of the primary reviewers of UL's original proposed standard. If the cable were marked as UL originally proposed, it would take a minimum of 9' to accommodate all the text. They settled on "MC-HL" after my comments to that requirement.

There is nothing in the NEC nor UL Standards that require filling any "-HL" cable to prevent the transmitting of gases/vapors. In fact, it is still a basic "continuous corrugated aluminum" construction, only with a higher price.

With regard to TC-ER, I was a major proponent. Why anyone felt a need to append "-HL" is beyond me except to jack up the price. It is still the common construction but tested to meet the crush/impact test of Type MC - which most Type TC constructions pass.

It is important to note TC-ER-HL is only recognized for use in Division 1 as a "flexible connection"; i.e., it is "super duper" - extra-hard usage [See Section 501.140].

Last, but not least, yep, "Since the factory sealed control station is not required to be explosionproof [at the cable entry], the cable is therefore not required to be sealed per 501.15(E)(1) [and (3)]"

501.15(E) Exception seems to lend any support for using MC-HL vs MC in Division 2.
“cables with an unbroken gas/vaportight continuous sheath shall be permitted to pass through a Division 2 location without seals”.

 

[rbalex]

501.15(E) Exception seems to lend any support for using MC-HL vs MC in Division 2.
“cables with an unbroken gas/vaportight continuous sheath shall be permitted to pass through a Division 2 location without seals”.

It depends on which construction of MC you are using; there are three. See Sections 330.2 and 330.116 [2017 NEC]. Type MC-HL is just conventional corrugated metallic sheath Type MC with a higher price tag. In fact, only the "interlocking metal tape armor" construction fails to meet the Exception.

BTW any form of Type TC is also acceptable. Types TC-ER and TC-ER-HL are also just conventional Type TC costructions that passed the crush and impact tests for Type MC, which almost any Type TC can pass. But "-ER", "-ER-HL", or not, any form of Type TC meets the Exception.

The "root text" of Section 501.10(B)(1) does not support the mandatory or exclusive use of MC-HL in Division 2. You can certainly use it of course, it simply isn't required.

 

[Dale001289]

Thanks Bob -- looks like TC may be the best option.


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[GoldDigger]

501.15(E) Exception seems to lend any support for using MC-HL vs MC in Division 2.
“cables with an unbroken gas/vaportight continuous sheath shall be permitted to pass through a Division 2 location without seals”.

Note the very large difference between passing (unbroken) through a Div 2 and originating or terminating there.

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[rbalex]

Note the very large difference between passing (unbroken) through a Div 2 and originating or terminating there.

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It's analogous to several other Exceptions for conduits in Section 501.15, such as 501.15(A)(4) Ex. No.1[Division 1] and (B)(2) Ex. No.1. [Division 2].

 

[Dale001289]

501.15(D)(1)

501.15(D)(1)

It's analogous to several other Exceptions for conduits in Section 501.15, such as 501.15(A)(4) Ex. No.1[Division 1] and (B)(2) Ex. No.1. [Division 2].

Bob, can you confirm the following statements - CID1, Gps C & D:

• MC-HL cable entering enclosure that is explosionproof and factory sealed (such as C-H EDS series) cable end must be sealed, i.e. C-H TMCX or equal cable gland.
• MC-HL cable entering enclosure, that is explosionproof with no arcing device such as motor termination box, cable end must be sealed, i.e. C-H TMCX or equal cable gland.
• Rigid metal conduit entering explosionproof, factory sealed device with TC-ER cable routed within conduit, no conduit seal is required and cable within conduit does not have to be sealed.

Thanks in advance,
Dale

 

[rbalex]

Bob, can you confirm the following statements - CID1, Gps C & D:

• MC-HL cable entering enclosure that is explosionproof and factory sealed (such as C-H EDS series) cable end must be sealed, i.e. C-H TMCX or equal cable gland.
• MC-HL cable entering enclosure, that is explosionproof with no arcing device such as motor termination box, cable end must be sealed, i.e. C-H TMCX or equal cable gland.
• Rigid metal conduit entering explosionproof, factory sealed device with TC-ER cable routed within conduit, no conduit seal is required and cable within conduit does not have to be sealed.

Thanks in advance,
Dale

The first sentence of Subsection 501.15(D)(1) states the "where" all cables must be sealed. It makes no distinction about the Type of enclosure or its features or the Type of cable itself. The rest of Subsection 501.15(D) and subsequent Subsections, including the Exceptions, deal with the "how" for sealing various Types of cables and their constructions and enclosure features don't matter much within the context of Class I, Division 1; i.e., cables still must be sealed at the terminations.

That said, the first two bullets are fine. The third bullet is problematic since Type TC (of any kind) must still be sealed at the terminations. It is permitted to omit boundary seals for Type TC and other constructions but not the conduit.

 

[Dale001289]

The first sentence of Subsection 501.15(D)(1) states the "where" all cables must be sealed. It makes no distinction about the Type of enclosure or its features or the Type of cable itself. The rest of Subsection 501.15(D) and subsequent Subsections, including the Exceptions, deal with the "how" for sealing various Types of cables and their constructions and enclosure features don't matter much within the context of Class I, Division 1; i.e., cables still must be sealed at the terminations.

That said, the first two bullets are fine. The third bullet is problematic since Type TC (of any kind) must still be sealed at the terminations. It is permitted to omit boundary seals for Type TC and other constructions but not the conduit.

Third Bullet: Ok, so CID1, TC cable ends still needs to be sealed at the Factory Sealed enclosure - fine. This basically brings me right back to installing a conduit seal, i.e. C-H EYD at the control station - correct?
If the cable were single conductors instead of TC, could the seal then be omitted per Article 501.15(A)(1) Exception b?

Also if it were CID2, same scenario, I assume TC cable would NOT have to be sealed at the termination for the Factory Sealed device?

Thanks again, in advance.
Dale

 

[rbalex]

Third Bullet: Ok, so CID1, TC cable ends still needs to be sealed at the Factory Sealed enclosure - fine. This basically brings me right back to installing a conduit seal, i.e. C-H EYD at the control station - correct?
If the cable were single conductors instead of TC, could the seal then be omitted per Article 501.15(A)(1) Exception b?

Also if it were CID2, same scenario, I assume TC cable would NOT have to be sealed at the termination for the Factory Sealed device?

Thanks again, in advance.
Dale

Note the first sentence of Subsection 501.15(D)(1) says nothing about single nor multiconductor tables. To be genuinely horrified read Section 501.15 Informational Note No. 2. Be grateful there's no enforceable language.

This was a topic of some discussion some years back. It was considered by several CMP14 members that simply sealing the end of a multiconductor cable with a mastic filled heatshrink tube would be “suitable” [500.8(A)]and a factory sealed device wouldn’t require an external conduit seal. In fact,we had discussions with most of the major heatshrink manufacturers and were assured there would be no problem making such a product. The NRTLs were a bit concerned about the product testing though and we weren’t quite able to agree on wording either

Ultimately, we wimped out and said it wasn’t too common a practice to use multiconductor cables in conduit in Division 1. That is generally true for power, less so for instrumentation; nevertheless, it was dropped.

As for revising bullet three for a Class I, Division 2 application, you are correct.

 

[Dale001289]

Note the first sentence of Subsection 501.15(D)(1) says nothing about single nor multiconductor tables. To be genuinely horrified read Section 501.15 Informational Note No. 2. Be grateful there's no enforceable language.

This was a topic of some discussion some years back. It was considered by several CMP14 members that simply sealing the end of a multiconductor cable with a mastic filled heatshrink tube would be “suitable” [500.8(A)]and a factory sealed device wouldn’t require an external conduit seal. In fact,we had discussions with most of the major heatshrink manufacturers and were assured there would be no problem making such a product. The NRTLs were a bit concerned about the product testing though and we weren’t quite able to agree on wording either

Ultimately, we wimped out and said it wasn’t too common a practice to use multiconductor cables in conduit in Division 1. That is generally true for power, less so for instrumentation; nevertheless, it was dropped.

As for revising bullet three for a Class I, Division 2 application, you are correct.

They've routed TC-ER into sump pits (CID1) via rigid aluminum conduit; placed boundary seals correctly, but failed to seal the cable ends per 501.15(D)(1), (i.e.using conduit seals), at the control stations AND the motor termination boxes.
Really appreciate the feedback.

 

[Dale001289]

Note the first sentence of Subsection 501.15(D)(1) says nothing about single nor multiconductor tables. To be genuinely horrified read Section 501.15 Informational Note No. 2. Be grateful there's no enforceable language.

This was a topic of some discussion some years back. It was considered by several CMP14 members that simply sealing the end of a multiconductor cable with a mastic filled heatshrink tube would be “suitable” [500.8(A)]and a factory sealed device wouldn’t require an external conduit seal. In fact,we had discussions with most of the major heatshrink manufacturers and were assured there would be no problem making such a product. The NRTLs were a bit concerned about the product testing though and we weren’t quite able to agree on wording either

Ultimately, we wimped out and said it wasn’t too common a practice to use multiconductor cables in conduit in Division 1. That is generally true for power, less so for instrumentation; nevertheless, it was dropped.

As for revising bullet three for a Class I, Division 2 application, you are correct.

Art 501.15(A)(1) Exceptions a-b, lead you to believe conduit seals can be omitted. But when you look at 501.15(D) - especially when routing TC cable in conduit - you're right back to installing the conduit seal regardless, AND there doesn't seem to be any cross-referencing between the two Articles. Is it just me, or is this an area of the code that deserves clarification on the next cycle?

 

[rbalex]

Art 501.15(A)(1) Exceptions a-b, lead you to believe conduit seals can be omitted. But when you look at 501.15(D) - especially when routing TC cable in conduit - you're right back to installing the conduit seal regardless, AND there doesn't seem to be any cross-referencing between the two Articles. Is it just me, or is this an area of the code that deserves clarification on the next cycle?

So make a Public Input. You're running out of time though.