class 1 div 1

[switchgear]

I am installing class 1 div 1 motors/electric mixers of various hp in a class 1 div 1 room. These mixers are intended for travel in and out of open-type mixing tanks or vats. I think I might be misinterpreting the code slightly. As a flexible connection we are installing killark bronze flexible coupling which are rated for this application but are extremely expensive (ex: $400-500 for 36" of 1-1/4" (YES 3 FEET). I believe that I can use flexible cord but fittings are a problem. Somewhat vague requirement. :roll: :roll:

Edited to remove your e-mail address, please use the PM (private message) system to contact someone and then exchange e-mail addresses in private.

Thanks,
Charlie

[ November 13, 2004, 08:44 AM: Message edited by: switchgear ]

 

[rbalex]

Re: class 1 div 1

Section 501.11 would permit using flexible cords in this application. What do you believe is vague?

 

[petersonra]

Re: class 1 div 1

Originally posted by rbalex:
Section 501.11 would permit using flexible cords in this application. What do you believe is vague?

Extra hard service cords as I recall. The problem is that IIRC, No one makes a seal fitting designed for use with a cord that is UL listed. There are seal fittings made for this purpose but they come with a red tag on them indicating the assembly is not UL listed. It seems UL will not list a product for this purpose unless there is some way to replace the cord in the event of damage, and being glued into a seal makes it very difficult to replace the cord.

From my long chat some time ago with the product manager at one of the companies that makes these things, they take a standard seal,and add a Cl1-Div2 rated cable gland to it. He said UL forces them to add the red tag if they do it, but not if you make the same assembly up.

Personally, I cannot see any hazard in doing this, however he said inspectors occasionally object since the cable gland is not rated for Div1.

 

[rbalex]

Re: class 1 div 1

There are several "extra-hard usage" cords. Almost every one listed in Note 4 of Table 400.4 is. Seal fittings are require to be "suitable" - they are not required to be "listed" specifically for the cords. Basically a "listed" bushed fitting is used to connect the cord to a seal fitting where required. See 501.4(B)(2)for example.

Both application cases(the first two sentences of 501.11) are MANDATORY PERMISSIVES, i.e., they SHALL be permitted and an AHJ has no Code basis for rejecting them.

 

[elektrafried]

Re: class 1 div 1

If you use a cord,where are you going to make your joints?I haven't hooked up every type of class 1/div.1 motor but all the small ones I have hooked up had the leads long to reach through the flex to the jb and were sealed between the peckerhead and the inside of the motor,I assumed to keep joints from being made in the peckerhead.If you use cord,how do you seal it? Hoping to learn something here,not being facetious.

 

[rbalex]

Re: class 1 div 1

For most common Division 1 applications, motors must be listed for Class I, Division 1[See 501.8(A)(1)] For such motors, the motor terminal box, and the motor enclosure are separate XP enclosures with an integral seal between them. It is intended that the motor terminations are to be made in the motor terminal box.

In general, flexible cables are to be sealed per 501.5(D),with special emphasis on 501.5(D)(2). Assume the cables are capable of transmitting gases through the core and ignore the exception.

The simplest direct approach would be:

1. Attach "suitable" sealing fittings to motor terminal box and auxiliary junction box.
2. Strip flexible cable back
3. Use listed bushing to connect cable to sealing fittings.
4. Pour seals
5. Terminate conductors.

There may be other variations such as "sealing glands" or the auxiliary J-box may be in a Div 2 or unclassified location and sealing may or may not be required there. The principal goals are maintaining the integrity of the XP motor terminal box and preventing the cable from becoming a transmission route for flammable materials. See 501.5 FPN 1.

 

[elektrafried]

Re: class 1 div 1

Thanks,I didn't realize the 'peckerhead' was considered a seperate xp enclosure,I'd assumed the reason the wires were 4 or 5 feet long was to reach through the flex to a jb.

 

[rbalex]

Re: class 1 div 1

"Switchgear" sent me the following PM:

3. Use listed bushing to connect cable to sealing fittings.


THE BUSHING LISTED IN (3.) ABOVE. LISTED TO DO WHAT?
THE CORD IS A 4 - 3AWG

He has not appeared to have yet read the following reply:

Personally I'd use a Kellem's Grip style to get both a bushing and the strain relief required by 501.11(4). I'd also pick a termination method that was resistant to vibration although the NEC doesn't really require it.

http://www.hubbell-wiring.com/library/SectionT-part1.pdf

Starting about Page T-59.

The only real purpose for the bushing is to prevent chaffing - as it would be in any case, classified location or not. Proper fibre packing and pouring the seal"... so that the sealing compound will surround each individual insulated conductor and the outer jacket" is what is important, for the Div 1 application.

I don't want to give the impression that I don't think Division 1 is dangerous,but for this particular application it's just not as serious as many folks treat it.

The bushings do not need to be specifically "identified" for Class I any more than the "extra hard usage" cord does.

I should also add the "termination method" I referred to was with respect to the conductors. A "typical" IEC motor in Zone 1, would have an Exd(flameproof) motor enclosure with an Exe (increased safety) motor terminal box. The terminations would be Exe, which essentially means they are vibration and pull-out resistant. IEC considers non-Exe terminations arc-making, even in Zone 2. In theory, the NEC doesn't consider terminations arc-making although we do tip our hat to them in 501.5(A)(1)(2) in Division 1 locations.

[ November 16, 2004, 01:48 PM: Message edited by: rbalex ]