Class 1 Division 2 ventilation? 2

[drvcivil]

NFPA 820, Table 4.2 indicates that a Residential Wastewater Pumping Station Wetwell is a Cass 1, Division 2 Location. If I specify Class 1, Division 2 rated submersible pumps, do I have to ventilate the wetwell or do I have to use a Combustable Gas Detector(CGD? If a CGD is used, does it have to be wired to the pump starters to cancel pump start if gas is detected?

 

[peebee]

Note that you are OK to run even a general-purpose motor in a Class I Div 2 location continuously, provided that there are no contacts, brushes, switches, overloads, etc., in the motor. The motor itself is generally not a problem, it's those other associated sparking types of devices that can cause an explosive atmosphere to ignite. See NEC 501.8(B) for exact requirements and additional details. Be particularly careful of the overload devices often embedded in small GP motors -- those would need to be removed from the motor to comply with this requirement (and replaced with remote OL devices located remotely, at the motor controller or elsewhere).

So, focus more on things like switches and brushes. Those are the things that need to be XP rated, or kept entirely out of the hazardous area.

In general, no, there's nothing to prohibit you from running the motor when an explosive gas is present in a ClI D2 area.

 

[NEMA6P]

Practicality aside, you are better off from a legal liability standpoint to get a pump that is approved for use in a class 1 div 2 area. The pump vendor should have 3rd party regulatory approval of his unit from UL or Factory Mutual or similar. That way if there was ever a problem, you wouldn't be hanging out to dry. You're not the only guy who ever needed a pump in a wastewater pumping station wetwell, so the approved pump is out there on the market.

I search for stuff like that on UL's website. Go to the main page, then pick certifications. You will have to do some research to find the UL category for the pump (the UL CCN). After you uncover that, you can search by the category to find a list of all approved manufacturers around the globe.

Best of Luck.

NEMA6P

 

[jraef]

Hold on, hold on, he said SUBMERSIBLE pumps. You don't need to worry about the Cl1D2 rating of the motor if the entire pump is under the poop!

The tricky thing is making sure the level controls are properly rated. You need to either use Intrinsically Safe Relays (search that term) or Cl1D2 rated devices.

"Venditori de oleum-vipera non vigere excordis populi"

 

[NEMA6P]

I thought Div 2 means "where explosive atmospheres may be present from time to time during normal use" (paraphrased approximately).

If it's a classified area, you must use rated equipment. This is probably to cover those occasions, even if infrequent, where the pump may be exposed.

Have a look at UL standard 1207 "Sewage pumps used in hazardous (classified) locations" for more info.

Safety First!

 

[peebee]

Re: "If it's a classified area, you must use rated equipment"

Not true. From NEC 501.8(B):
". . . the installation of open or nonexplosionproof enclosed motors . . . without brushes, switching mechanisms, or similar arc-producing devices that are not identified for use in a Class I, Division 2 location, shall be permitted."

In Cl I Div 2 areas, your main concern is spark producing devices.

 

[weh3]

Your other concern is surface temperature, NEC 500-5(d). The GP motor may have an open-to-atmosphere thermal cutout that would make it unsuitable for use in a classified area.

Wm

 

[DRWeig]

Guys, I'm going to pitch in with Peebee on this one. I've had a lot of hazloc experience, and an induction motor isn't an issue in Div 2.

One thing that this brings up: Certain electronic devices may be labeled "non-incendive" for use in Div 2 areas, but I've never run across a motor or enclosure that is labeled or listed for Div 2. The code specifies that in a Div 2 area, if you don't have surface temperature issues or arcing/sparking devices, a "general purpose" enclosure is all that is required. Otherwise, enclosures must be rated for Div 1. Can anybody point me at a motor listed for Div 2 that isn't also listed for Div 1? I'd like to have that in my bag of tricks if it exists...

On the thermal cutout issue, that is a valid point if the motor is small. For small motors, impedance protection is better in this case.

Of course, your starter and stuff must be explosionproof unless it can be located outside the hazardous area.

Holla back!

Best to ya,

Old Dave

 

[rbalex]

I was going to avoid this one since Peebee is absolutely right; however, UL has been listing motors for Division 2 for about a year now. It is still not an NEC requirement.

Check UL's online certification directory at

http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/ccnsrch.html

and do a “Category Code” search on “PTHE.” For an interesting side issue, do the same search on “PRGY.”

 

[DRWeig]

Thanks rbalex!

This is why I come to this forum. I had no idea UL was doing that.

Best to all,

Old Dave

 

[jraef]

Moot point anyway, it is still a submersible pump!

 

[weh3]

Look at 501-8(b). Motors in Div 2 can be GP unless they have a thermal cutout, in which case, the motor has to be a Div 1 motor.

Wm

 

[weh3]

Just because the pump is submersible doesn't mean that it is continually submerged. The wastewater pumping stations I have seen often have the pump motor above the low level shutoff.

Wm