DC Gear motor in hazardous location

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housemoney

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Got a job requiring upgrade wiring methods and materials to C1D1- nothing wired as a haz. location currently. They have about 16 of these SEW DC gear motors - I couldn't get nameplate, crap all over them.

Assuming they are not explosion proof as nothing in the room is currently. Are these things a serious concern for source of ignition? Owner would like to keep them via AHJ permission as they are only 15 years old

Thoughts?

sew.jpg
 
I don't think any one with half a brain or more is going to allow you to claim that a DC motor that is not explosion-proof is suitable for a Class I Division 1 area. You might be able to find some way to purge these motors but it would probably be cheaper to just buy new explosion-proof Motors. The other option is to see if there's some way you can rearrange the room so that only it is hazardous and the part where the motors are is not. Might have to do some repiping which might or might not be cheaper. Another option is to buy AC Motors and put small vfds on them. But I don't see any way anyone is going to accept your idea of not changing them to save money.

I am almost afraid to ask this but what has changed to make them believe that what was a non-classified area has suddenly turned into a Class I div 1 area?
 
Not my idea- I’d love to sell the owner new motors:) -their maint engineer idea.

Nothing changed. 15 years ago this place should have been c1/D1- previous engineering firm screwed up, apparently the inspector let it slide- apparently.

I dont know a thing about DC motors - can you give me a sentence or two on how to convince the owner that they need to abandon the idea of salvaging them?

Going to have to go exp proof DC? Or exp proof AC selected for the High torque gear load?
 
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DC motors (and universal motors) have a commutator and brushes, which create a continuous electric arc while operating.
Single-phase motors have a centrifugal speed switch, which creates an arc each time the motor starts.
Three-phase induction motors don't have any built-in arc sources. (which doesn't automatically make them explosion proof)
https://www.youtube.com/watch?v=gc4l1eooPKM
 
Class I, Division 1 doesn't really care whether the motors are DC or AC and the suitable protection techniques are extremely limited (and expensive). [Section 501.125(A)]

Bob (petersonra) asked the first correct question - "What changed to make it Division 1 now?" In light of the OP response, the next question is, "After 15 years without apparent incident, what would lead one to believe the location should have been classified Division 1 in the first place?" A correctly classified Division 1 location is not a particularly forgiving environment although I can describe a few correctly classified Division 1 situations that may not actually become hazardous - very rare, but possible.
 
rbalex said:
Class I, Division 1 doesn't really care whether the motors are DC or AC and the suitable protection techniques are extremely limited (and expensive). [Section 501.125(A)]

Bob (petersonra) asked the first correct question - "What changed to make it Division 1 now?" In light of the OP response, the next question is, "After 15 years without apparent incident, what would lead one to believe the location should have been classified Division 1 in the first place?" A correctly classified Division 1 location is not a particularly forgiving environment although I can describe a few correctly classified Division 1 situations that may not actually become hazardous - very rare, but possible.
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Good points if I may say so. I'd be cautious about the absence of incidents as a measure though.
 
Besoeker said:
Good points if I may say so. I'd be cautious about the absence of incidents as a measure though.
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Trust me, a correctly identified NEC Division 1 and IEC Zone 1 aren't nearly as analogous as many would care to believe. The overlap of NEC Division 2 and IEC Zone 1 is actually quite great.
 
I think it would be very wise for the owner to pay somebody competent to take a look at this installation. I'm wondering who decided that it was incorrectly classified in the first place.
 
rbalex said:
Trust me, a correctly identified NEC Division 1 and IEC Zone 1 aren't nearly as analogous as many would care to believe. The overlap of NEC Division 2 and IEC Zone 1 is actually quite great.
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I not disputing that. I was making a quite different point.
 
Besoeker said:
I not disputing that. I was making a quite different point.
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In many cases, I believe your point is well taken. My consideration was reflecting on Post #1 itself stating that none of the wiring or equipment was installed to Division 1. NEC Division 2 often permits "general purpose" equipment and occasionally wiring methods that may be common in ordinary locations; Division 1 doesn't. Within 15 years something would have happened although I have no idea what. An properly classified Division 1 location is actually quite rare.
 
Municipal sewage treatment facility lacking half the number of air exchanges per hour to make it C1D2 per NFPA 820

rbalex said:
Class I, Division 1 doesn't really care whether the motors are DC or AC and the suitable protection techniques are extremely limited (and expensive). [Section 501.125(A)]

Bob (petersonra) asked the first correct question - "What changed to make it Division 1 now?" In light of the OP response, the next question is, "After 15 years without apparent incident, what would lead one to believe the location should have been classified Division 1 in the first place?" A correctly classified Division 1 location is not a particularly forgiving environment although I can describe a few correctly classified Division 1 situations that may not actually become hazardous - very rare, but possible.
Click to expand...
 
rbalex said:
If we're going to play the semantic game fine; however, I believe you're still thinking Zone 1 where could may be marginally more appropriate. I will stand by my position.
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I can't still be thinking of Zone 1 given that I wasn't thinking about it in the first place.
 
rbalex said:
OK, I can accept you weren't thinking and just wanted to play semantics.
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Really??
I'm making the very simple point that we can speculate what might have happened. Without that magic crystal ball we can't express certainty about what would have happened. Fifteen years without incident doesn't mean there couldn't be one tomorrow. That's why I said it isn't a good or reliable measure.
No semantics involved, at least not from me.
 
Please, lets drop the could-should p***ing contest. The 1st 8 posts pretty well answered the question but I'd like to keep the thread open and on-topic in case anyone can help the OP with factual input.
 
housemoney said:
Looks like 6.2.2(a) row 8, line a as it is infeasible to achieve 12 a/e per hr? Micro bubble flotation process area I’m told.
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Even 15-20 years ago the standards, including NFPA 820, NEC documentation, and motor requirements were essentially the same. Not knowing the full facility details, I'm in no position to say what it should have been then or should be now unless NFPA 820, Table 6.2.2(a), Row 8 is, in fact, the correct application. In that case, there is no way to justify a motor that doesn't comply with Section 501.125(A).

It's hard to believe nothing has ever happened since a thickener can usually generate a fair amount of methane continuously.
 
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