c1d2

[rswolff001]

hello all wise and knowing of the electrical code!!!!

easy questions I believe......Class 1 Division 2

first.....am I reading section 501.120(B)(2) that a general purpose dry type transformer with a 3R enclosure would be allowable?
would that also include mounting a non enclosed transformer in a Nema12 enclosure?

would a standard non-fusible disconnect mounted in a standard Nema12 enclosure need to comply with 501.115(B)(1) or 501.115(B)(2)?

thanks,
bob

 

[rbalex]

Section 501.120 applies to control transformers. Power transformers are covered in Section 501.100 and instrument transformers are covered in Section 501.105.

In Class I, Division 2, transformers may be installed in general purpose (NEMA and UL call them "ordinary location") enclosures that are otherwise suitable for the environment. Table 110.28 (2014 NEC) lists indoor/outdoor general purpose enclosures.

Whether a standard non-fusible disconnect mounted in a standard Nema12 enclosure would comply with 501.115(B)(1) or 501.115(B)(2) would depend on its intent to interrupt current in the normal performance of the function for which it was are installed.

 

[rswolff001]

c1d2

thanks, I was pretty sure about the xfrmr.......the disconnect is still a question for me......the normal function of a disconnect is to interrupt current.................if the panel disconnect was used once a day would that infer its normal operation? how about once a week? when would a
disconnect's normal operation not be to disconnect current?

thanks, bob :dunce:

 

[rbalex]

An isolation switch [Section 501.115(B)(2)] does not interrupt current in its intended purpose. When opened, current has already been interrupted by some other device. Any other switch in Class I, Division 2, whether used daily or yearly or only for maintenance every 5 years or so, that is used to interrupt current, must comply with Section 501.115(B)(1). Such switches must also comply with Section 110.9, second paragraph.

Note to the nitpickers: I know Section 501.115(B)(2) also says "disconnect", but, if it is intended to interrupt current even under emergency conditions, the Section doesn't apply. Normal is undefined in the NEC; it doesn't necessarily mean common or usual, simply that it is performing its design purpose.

 

[rswolff001]

Disconnect

Disconnect

So what would you say a disconnect switch, mounted in the enclosure, with an operator on the door, is? Would you classify as an isolation switch (which doesn't need to comply) or a switch whose function is to interrupt current (which would need to comply)? There is a transformer mounted
externally to the enclosure (3R), which is fed through a couple of fuses being fed by the disconnect. So unless you open the enclosure and pull the fuses, the disconnect would be interrupting current unless the breaker feeding the panel was turned off.

FYI.....I've already told the client I don't believe the panel meets code because of not only the disconnect, but the panel also has a standard motor contactor (that's definitely interrupting current in normal operation) and a few push buttons mounted in the enclosure door that also interrupt current of some sort.

They also have something I thought was peculiar.....there are three(3) solenoid valves with intrinsically safe coils mounted inside the enclosure.....the specification shows they need to be fed through barriers.....there are no barriers.....I would say they are therefore unclassified and can't be used in a C1D1 area enclosure in that fashion. Any thoughts?

Thanks, Bob :blink:

 

[rbalex]

So what would you say a disconnect switch, mounted in the enclosure, with an operator on the door, is? Would you classify as an isolation switch (which doesn't need to comply) or a switch whose function is to interrupt current (which would need to comply)? There is a transformer mounted
externally

If you can't figure that one out on your own, I'd say read and memorize the last sentence of Section 90.1.

Unless there is signage that says, "Do not open under load" or something similar, of course the switch interrupts current in its design function and must meet Section 501.115(B)(1). Opening the enclosure and pulling the fuses would very likely be an NFPA 70E violation of its own. Most would open the disconnect before removing the fuses.

I would agree that the installation as you have described it is not suitable for Class I, Division 2.

Installed as "intrinsically safe" (IS), the solenoids are not in the scope of Article 501. To be installed properly as IS, they must comply with Article 504. Whatever barriers were installed for them would not be in the classified location in the first place. Oddly enough, they may be fine in Division 2 anyway. See Section 501.105(B)(3). I'd want to see their nameplate.

 

[rbalex]

BTW signage saying, "Do not operate under load" has limited application for motors. See Section 430.109(E).

 

[rswolff001]

c1d2

Actually I was simply asking for confirmation.......I spoke with several other electricians, posted at another forum, and also asked several others I know, and we all were on the same page....I was simply confirming that there wasn't some 'interpretation' that somehow allowed this and we were all missing something.

This is an existing panel......I turned down the project several years ago based on the fact that I didn't see any reasonable way to do what was requested without using a purged enclosure. I was also not pleased with the fact that the end user was either unaware or unconcerned about proper code for the classified area. So my client (I do other work for them) found someone else. They've recently asked me to quote a duplicate panel going into another location also C1D2. After reviewing the documentation as to what was supplied I simply responded that I would not quote as the existing panel didn't meet code requirements. They indicated everyone else thought it did (the supplier and the end user). I went back and checked what I expect were the appropriate sections and still came to the conclusion it didn't meet code. Not one to work in a vacuum, I asked others, and also posted the questions here. I've posted here before (If memory serves me you answered those posts also). Asking advice of those who either have more experience or more exposure, or are possibly simply better versed simply leads to fewer issues. Its when you believe you're smart enough that problems occur. As a wise person once told me, the more you learn, the more you'll realize how stupid you actually are.

I thank you for your feedback and valued advice.

Bob :dunce:

 

[rbalex]

Actually I was simply asking for confirmation.......I spoke with several other electricians, posted at another forum, and also asked several others I know, and we all were on the same page....I was simply confirming that there wasn't some 'interpretation' that somehow allowed this and we were all missing something.

This is an existing panel......I turned down the project several years ago based on the fact that I didn't see any reasonable way to do what was requested without using a purged enclosure. I was also not pleased with the fact that the end user was either unaware or unconcerned about proper code for the classified area. So my client (I do other work for them) found someone else. They've recently asked me to quote a duplicate panel going into another location also C1D2. After reviewing the documentation as to what was supplied I simply responded that I would not quote as the existing panel didn't meet code requirements. They indicated everyone else thought it did (the supplier and the end user). I went back and checked what I expect were the appropriate sections and still came to the conclusion it didn't meet code. Not one to work in a vacuum, I asked others, and also posted the questions here. I've posted here before (If memory serves me you answered those posts also). Asking advice of those who either have more experience or more exposure, or are possibly simply better versed simply leads to fewer issues. Its when you believe you're smart enough that problems occur. As a wise person once told me, the more you learn, the more you'll realize how stupid you actually are.

I thank you for your feedback and valued advice.

Bob :dunce:

In that case, I would support you.

 

[rswolff001]

c1d2

forgot to mention......the documentation on the solenoids did not indicate they were C1D2 compliant......I haven't actually seen the panel itself, only the BOM and schematics. I pulled the specifications and certifications on the solenoids to review. Ditto for the rest of the components being used.


Thanks Again,
bob :dunce:

 

[rbalex]

The reason I pointed you to Section 501.105(B)(3) is the solenoids wouldn't necessarily indicate they were rated for Class I, Division 2. A general purpose enclosure is acceptable. Also see Section 500.8(C)(6)(a). Unless the nameplate/manufacture's data indicated they were only suitable for IS, they would be fine in Division 2.