Motor starter help for in a Class 1, Div 1, Group B, T4 (T4 = Permissible Surface Temperature of 135C)

emiller233

Senior Member
Location
pittsburgh, pa
We need an Enclosed motor starter, preferably with disconnect switch and a few pushbuttons (motor start/stop/ect). and from what I understand the T4 rating can only be given if its factory assembled and given that rating? They originally asked for a T6 rating but have lowered it to T4. I'm not sure where to even begin with this. ive reached out to a few explosion-proof enclosure companies and they all tell me they cant hit the T4 rating...

It is for in a: Class 1, Div 1, Group B, T4 (T4 = Permissible Surface Temperature of 135C)

Motor will be running on 240VAC 3-phase line
Voltage: 208-230/460 V
Full Load Amps: 14.5-13.1/6.57 A
http://catalog.wegelectric.com/produtoInformacao.asp

thanks in advance!
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
At the moment, "they" are specifying a unicorn and we would need more information about the specific gas or vapor you are dealing with. Typically, but not necessarily, Group B means hydrogen which has an Autoignition Temperature (AIC) of 520C. There are a few other Group B materials though with lower AICs but I don't know any with AICs that would require a T4 (135C) rating.

You are correct that the entire assembly would need to be identified for Class I, Division1. [Section 501.115(A)]
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
At the moment, "they" are specifying a unicorn and we would need more information about the specific gas or vapor you are dealing with. Typically, but not necessarily, Group B means hydrogen which has an Autoignition Temperature (AIC) of 520C. There are a few other Group B materials though with lower AICs but I don't know any with AICs that would require a T4 (135C) rating.

You are correct that the entire assembly would need to be identified for Class I, Division1. [Section 501.115(A)]
I stand corrected, I found one Group B material (Propyl Nitrate) with an AIC (175C) significantly lower than most others. I've never worked with it but T4 might be reasonable. Typically though, 175C would be T3B unless you are dealing with a Zone (Article 505) classified location.
 

emiller233

Senior Member
Location
pittsburgh, pa
I stand corrected, I found one Group B material (Propyl Nitrate) with an AIC (175C) significantly lower than most others. I've never worked with it but T4 might be reasonable. Typically though, 175C would be T3B unless you are dealing with a Zone (Article 505) classified location.
i don't have details yet, but it will be in a warehouse in the paint dept, so i'm assuming in or near the paint booth at this point?
I've never heard of the T4 rating until now, so this is going to be a crash course for me...
do i push them to re-evaluate the area classification, or if the stick to it, how do i meet the T4 rating they want?
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
i don't have details yet, but it will be in a warehouse in the paint dept, so i'm assuming in or near the paint booth at this point?
I've never heard of the T4 rating until now, so this is going to be a crash course for me...
do i push them to re-evaluate the area classification, or if the stick to it, how do i meet the T4 rating they want?
I would and they definitely need to have it done by someone who knows what they are doing. [Section 500.4] Folks, who specify certain electrical area classifications, "Just to be safe," usually paint themselves into a corner.
 

Jraef

Moderator
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
The T ratings apply to ATEX, the IEC Explosion Proof rating system, it basically has no equivalency here with regard to UL or NEC classifications. Your specifier can ask for whatever they want, that doesn't mean it is available. You would have to look for explosion proof starter mfrs that service both the North American and International markets with one product, because you are going to need UL listing (or some equivalent NRTL), but also have that ATEX temperature rating. Good luck with that, most mfrs focus on one set of specs or the other, or offer different products depending on which spec you need to meet.
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
The T ratings apply to ATEX, the IEC Explosion Proof rating system, it basically has no equivalency here with regard to UL or NEC classifications. Your specifier can ask for whatever they want, that doesn't mean it is available. You would have to look for explosion proof starter mfrs that service both the North American and International markets with one product, because you are going to need UL listing (or some equivalent NRTL), but also have that ATEX temperature rating. Good luck with that, most mfrs focus on one set of specs or the other, or offer different products depending on which spec you need to meet.
Brother, you know I wouldn't normally argue with you but see Sections 500.8(C)(4) and 500.8(D). T-ratings or T-Codes definitely apply beyond ATEX or IEC.
 
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