Explosionproof Data Jack
- Thread starter shawn474
- Start date
- Status
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
Re: Explosionproof Data Jack
Division 1 is serious business. I haven't seen the electrical area classification drawings so I can't make a conclusive statement but this sounds like an explosion waiting to happen - and fairly soon.
Clarify one more thing for me. You noted the mainitenance supervisor claimed they haden't used interlocks before; have they used this installation with the CPU in the Div 1 location before?
You do understand it correctly. This is frightning. From Hal's second post I assumed the computer would be remote in its final state.
Division 1 is serious business. I haven't seen the electrical area classification drawings so I can't make a conclusive statement but this sounds like an explosion waiting to happen - and fairly soon.
Clarify one more thing for me. You noted the mainitenance supervisor claimed they haden't used interlocks before; have they used this installation with the CPU in the Div 1 location before?
Re: Explosionproof Data Jack
I asked the same question,the Head Maintenance guy claims all of their stores have the computer in the mix room,the G.C. does nothing but build these shops in the Southeast,he says the old man is full of it,the computer is outside the room in all the installations he has supervised.
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
Re: Explosionproof Data Jack
I?m concerned. If you said all (or even some) of the other installations had the computer in the room, I?d say we were missing something important. If all the other installations have the computer remote, it could explain why they haven?t had a problem yet ? and may never have one.
Truth is, if the circuit is IS, how the connecting cable is routed doesn?t make much difference. A hole in wall would probably work with no sealing at all. (This isn?t a recommendation) A small Division 2 area would be created outside the room around the hole. Depending on several factors, mostly air flows and the size of the hole, it could easily be less than a foot. I seriously doubt it would be more than 3.
Theoretically, you could go years without recognizing a problem - even if the computer or some other arcing, sparking, or heat producing (ASH) device was in that Div 2 area. A constant heat producer like the computer or a luminare would actually concern me more than a breaker or switch. The odds are in your favor with Div 2 - just not overwhelmingly.
Division 1 is different. A fire or explosion is almost certain; and sooner rather than later.
I?m concerned. If you said all (or even some) of the other installations had the computer in the room, I?d say we were missing something important. If all the other installations have the computer remote, it could explain why they haven?t had a problem yet ? and may never have one.
Truth is, if the circuit is IS, how the connecting cable is routed doesn?t make much difference. A hole in wall would probably work with no sealing at all. (This isn?t a recommendation) A small Division 2 area would be created outside the room around the hole. Depending on several factors, mostly air flows and the size of the hole, it could easily be less than a foot. I seriously doubt it would be more than 3.
Theoretically, you could go years without recognizing a problem - even if the computer or some other arcing, sparking, or heat producing (ASH) device was in that Div 2 area. A constant heat producer like the computer or a luminare would actually concern me more than a breaker or switch. The odds are in your favor with Div 2 - just not overwhelmingly.
Division 1 is different. A fire or explosion is almost certain; and sooner rather than later.
Re: Explosionproof Data Jack
-Shawn
Stopped by the job for a quick minute this morning.The IS barrier,MTL 7761 PAC has indeed been purchased and is installed in the haz. loc.The installer (Sherwin-Williams rep.) has also installed a box (in the haz.loc.) that takes a 110v supply and the OUTPUT is IS,listed Class 1/Div 1/Gp. C.D./T4 it says A s s. Equip. Blue cable provides int. safe Cl.1 Grp C + D.This is the power supply to the scale,the blue cable referred to is 20-25 feet long and the (white) cord on the box is a regular 115v,not xp.I am thinking this device is a xformer and the blue cord is supposed to be run into the mix room from outside the haz.loc.,it plugs into the scale.The MTL 7761 PAC has a gray cable and a blue cable,the gray cable goes to the CPU and the blue cable goes to the scale.This blue cable is also 20-25 feet long.While I have no doubt that the CPU in this particular shop will not end up in the mix room,how far do I take it if my employer is only concerned with this particular job? Do I advise the paint booth manufacturer? The Auto body owners? Sherwin Williams? Most of these people don't want to hear me (although the VP of the paint booth co. did ask for my phone # when he saw some of my work) these guys want to do what they want to do.I already know what I think I should do,just looking for opinions.Thanks for all the help,btw,you guys are great and this is without question the best technical forum on the 'net.
-Shawn
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
Re: Explosionproof Data Jack
From the manufacturer's installation manual:
In the widest interpretation, this could be the "control drawing" we have talked about. There is probably something more formal, but this would be enforceable in the absence of anything else. Under 110.3(B) too. It doesn't address the CPU connection but the other manufacturer's citation did.
There is a similar diagram indicating installation in an environment classified by Zones. That installation uses a hardwired connection to the outlet in the classified location. I generally like Zones even though I fought against them in the '93 Code. As a matter of fact, I liked them then too. I just didn't like "mixing and matching" them with Divisions.
If the "white" cord you described were properly protected mechanically and hardwired to a properly installed Zone 1 outlet, I might buy it. I'd have to see it.
Getting the CPU out of the classified location relieves much of my concerns.
Who to tell? Has the AHJ had his crack at it?
Edit Added : I should have looked past the "Deutsch" Section. Appendix II is the control drawing
[ July 19, 2004, 06:06 PM: Message edited by: rbalex ]
From the manufacturer's installation manual:
In the widest interpretation, this could be the "control drawing" we have talked about. There is probably something more formal, but this would be enforceable in the absence of anything else. Under 110.3(B) too. It doesn't address the CPU connection but the other manufacturer's citation did.
There is a similar diagram indicating installation in an environment classified by Zones. That installation uses a hardwired connection to the outlet in the classified location. I generally like Zones even though I fought against them in the '93 Code. As a matter of fact, I liked them then too. I just didn't like "mixing and matching" them with Divisions.
If the "white" cord you described were properly protected mechanically and hardwired to a properly installed Zone 1 outlet, I might buy it. I'd have to see it.
Getting the CPU out of the classified location relieves much of my concerns.
Who to tell? Has the AHJ had his crack at it?
Edit Added : I should have looked past the "Deutsch" Section. Appendix II is the control drawing
[ July 19, 2004, 06:06 PM: Message edited by: rbalex ]
Re: Explosionproof Data Jack
AHJ made the trip today,told everyone concerned that the CPU must either be moved or he must get documentation that it is xp and the box that is marked 'OUTPUT is IS' must be moved out of the room.The maintenance guy sputtered that the computer is in the mix room at their other location and the AHJ smiled and said we should maybe go take a look at them.
AHJ made the trip today,told everyone concerned that the CPU must either be moved or he must get documentation that it is xp and the box that is marked 'OUTPUT is IS' must be moved out of the room.The maintenance guy sputtered that the computer is in the mix room at their other location and the AHJ smiled and said we should maybe go take a look at them.
- Status