class 1 div 1 seals

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103FLHX

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ARKANSAS
PART OF 501.15 STATES "Conduit seals shall be installed within 450 mm (18 in.) from the enclosure. Only explosionproof unions, couplings, reducers, elbows, capped elbows, and conduit bodies similar to L, T, and Cross types that are not larger than the trade size of the conduit shall be permitted between the sealing fitting and the explosionproof enclosure". MY QUESTION IS WHEN TRADE SIZE IS USED IS IT A REFERENCE TO THE CONDUIT OR THE THREADED ENTRY ON THE ENCLOSURE? EXAMPLE BEING IN A CL1 DV1 LOC. EXPLOSIONPROOF PANELBOARD WITH A 3 IN THREADED ENTRY AND USING A 3 IN NIPPLE, 3 IN UNION, 3 IN TO 1 IN REDUCER TO BE ABLE TO INSTALL A 1 IN TMCX, OR SHOULD IT BE REDUCED FROM 3 IN TO 1 IN AT THE PANEL AND BE DONE WITH IT? MAYBE THERE IS A PART OF THIS CODE SECTION I AM NOT READING RIGHT ANY HELP WOULD BE GREAT
 
kwired

kwired

Electron manager
Location
NE Nebraska
103FLHX said:
PART OF 501.15 STATES "Conduit seals shall be installed within 450 mm (18 in.) from the enclosure. Only explosionproof unions, couplings, reducers, elbows, capped elbows, and conduit bodies similar to L, T, and Cross types that are not larger than the trade size of the conduit shall be permitted between the sealing fitting and the explosionproof enclosure". MY QUESTION IS WHEN TRADE SIZE IS USED IS IT A REFERENCE TO THE CONDUIT OR THE THREADED ENTRY ON THE ENCLOSURE? EXAMPLE BEING IN A CL1 DV1 LOC. EXPLOSIONPROOF PANELBOARD WITH A 3 IN THREADED ENTRY AND USING A 3 IN NIPPLE, 3 IN UNION, 3 IN TO 1 IN REDUCER TO BE ABLE TO INSTALL A 1 IN TMCX, OR SHOULD IT BE REDUCED FROM 3 IN TO 1 IN AT THE PANEL AND BE DONE WITH IT? MAYBE THERE IS A PART OF THIS CODE SECTION I AM NOT READING RIGHT ANY HELP WOULD BE GREAT
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My take on this is if you are installing a larger conduit body, than the conduit you are effectively increasing the volume within the "sealed" enclosure allowing for presence of higher level of explosive gas which the enclosure may not be designed to protect from. Same reason why you have to have a seal between two separate enclosures containing arcing parts. If the two were identical and you did not provide a seal between them you have a potential explosion inside twice the volume - the enclosure was only designed and tested for handling an explosion within its own volume and the 18 inches of connecting raceway to the seals.
 
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dicklaxt

Senior Member
Reduce it at the panel hub and install your conduit seal, the TMCX can be screwed directly into the seal. A union or nipple is not required.

The TMCX terminator/connector is designed for use with metal clad cable or tray cable.I'm assuming that is what we are dealing with.

dick
 
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103FLHX

Member
Location
ARKANSAS
yes it is an mc-hl cable with 1 " tmcx(explosionproof) terminator. the conflict lies in the 3 inch threaded hole in the panel, so thats the "trade" size entry so a short 6 inch by 3 inch nipple is installed into the panel, instead of using a reducing bushing in the 3 inch panel hole as the 1 inch tmcx terminator would be considered the "conduit" trade size. i realize most reducers aren't npt threaded and will thread completely thru and enclosure most of the time.
 
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dicklaxt

Senior Member
Use a 3" x 1" threaded reducer directly into the 3"hub and the install the seal directly into the reducer then install the TMCX directly into the seal.

Electrical conduit reducers are taper threaded just like the conduit.

dick
 
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103FLHX

Member
Location
ARKANSAS
the tmcx is a seal as it is a pack type fitting so no need for eys type seal and the hub isnt in the list of explosion proof parts that can be between the seal and the enclosure.
 
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dicklaxt

Senior Member
I guess I'm once again not being clear,,,,,you keep speaking of the 3" hub on the panelboard being the trade size and it requiring a seal of 3" size because the hub is not listed as an acceptable fitting that is allowed. Im saying because its part of the enclosure it does not dictate the trade size requirement of the incoming unless it needs to be that large.If a 1" is the requirement as you stated then it becomes the trade size so it does not require a seal because the 2" and larger conduit entry requirement does not exist thus it does not need a seal on that account.It does need to be sealed because of the breakers within the panelboard.

The application data in the catalog I'm looking at says the TMCX can be used in DIV 1 when a seal is required,this may indicate in addition to also it is not clear in the catalog data that the hand packed squeased inplace epoxy is a gas seal, a moisture seal or both.I have a call in to a vendor/manufacturer but Friday afternoon may be a hurdle to overcome.

Now irregardless of the outcome of my phonecall and going back to your original question.

The enclosre hub size is not a governing factor.

dick
 
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103FLHX

Member
Location
ARKANSAS
that was my misunderstanding i was thinking of a myers type hub screwing into the threaded entry on the panelboard and not actually being a hub , sorry . in short you reduce at the hub to the trade size conduit(being 1 inch tmcx connector)entering the enclosure. for a CL1 DV1 location by code
 
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dicklaxt

Senior Member
Yep thats the way to go,,,,,,,,,,,,,BTW I just found the spec sheet on the TMCX and it is both a compound gas seal on the conductors and a moisture seal on the outer jacket but you knew that already:) ,,,,,,so you are good to go with nothing but a reducer and terminator.Sorry I miss led you.

dick
 
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dicklaxt

Senior Member
Yep thats the way to go,,,,,,,,,,,,,BTW I just found the spec sheet on the TMCX and it is both a compound gas seal on the conductors and a moisture seal on the outer jacket but you knew that already:) ,,,,,,so you are good to go with nothing but a reducer and terminator.Sorry I miss led you.

Out of curiosity what type/style is the panel board?

dick
 
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dicklaxt

Senior Member
If you are speaking of a hub you can attach or thread to a box or enclosure ie: Myers Hub,yes that is a fitting,,,,,,,if you are speaking of a threaded opening on an enclosure(integral,part off) it is not a fitting but is oft times referred to as a hub.

dick
 
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