3 piece couplings

Status
Not open for further replies.

n1163

New member
hello, does anyone know if three piece couplings are legal to use in a class 1 div 1 area? the one's in question are cast iron and the manufacturer is unknown.
 
n1163 said:
hello, does anyone know if three piece couplings are legal to use in a class 1 div 1 area? the one's in question are cast iron and the manufacturer is unknown.

Yes, there are GRSC coulplings that are made for Cl.I, Div.1 locations.

No, I would not use something that "looks like" a fitting that would mechanically fit the application but it is not stamped with the UL listing.
 

HighWirey

Senior Member
A hint from Heloise here . . .

Once you have the correct explosionproof union selected and installed, make sure you have it bought off before the fitting's embossed Class and Div become obscured. 'Obscured' in my orbit meant one thick coat of primer, and two thick topcoats! Obscured means something different to each of us . . .
Personally did not like the 4" grinder and wire wheel method of quality control.

Best Wishes
 

Rockyd

Senior Member
Location
Nevada
Occupation
Retired after 40 years as an electrician.
Appleton and Crouse-Hinds both make quality UNY (male) and UNF (female) three piece explosion proof unions. Stand by for sticker shock. Everything in classified spaces always costs...


PS about that paint, duct tape, or masking tape, over the lettering, before a wild man with a spray gun can help, duct is less ocvious and will hold paint normally( but not listed for such activities).
 
Last edited:

nakulak

Senior Member
all of above good advice - nothing worse than having to take the stuff all apart to replace some fittings that aren't xp, especially if it gets writtten up on a punch list and sent to everybody and their brother (making you look bad too) (-- voice of experience lol)
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
don_resqcapt19 said:
In this area a "3 piece coupling" is the item that is also known as an Erickson. This product is not suitable for use in a Class I, Division 1 area. You need an explosionproof union for that application.
Don
Don,

In a previous thread, I mentioned that I was unfamiliar with the term ?Erickson? and you responded with a T&B catalog cut.

I?ve now seen several catalog cuts of the ?Erickson? style and another ?three piece coupling? style that appeared to be something like a turn buckle arraignment. I still haven?t seen any of them ?up close and personal.?

I?m curious about the Erickson style. I believe I can tell from some of the cuts how it is installed but I?m still not absolutely sure.

The T&B description stated ?To couple and effectively bond threaded ends of rigid metal conduit/intermediate metal conduit where neither length of conduit can be rotated.? Assuming this is an accurate description of the application, if an ignition occurred in a raceway system coupled with one of these type fittings, is there any emission path through the coupling that is NOT through a threaded labyrinth?

Second question. Have you ever seen a listed union that was not explosionproof? I.e., it must both be listed and classified as a "union." I can?t seem to find any on the internet.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Bob,
Yes, there is a path without going through the labyrinth of the threads on a 3 piece coupling. You have one piece that looks like a reducing bushing (piece on the left in my link above). This is threaded on one conduit end. You have a coupling nut (piece on right). You slide this on the other conduit end. The last piece is a stopper ring that screws on the conduit with the coupling nut. You butt the ends of the conduits together and screw the coupling nut on to the reducing bushing. The path is where the conduits butt together, over the stopper ring and under the coupling nut and out. No threads.
As far as what I would call a union....I have never seen one that was not a listed as suitable for classified locations.
Don
 

HighWirey

Senior Member
"if it gets writtten up on a punch list and sent to everybody and their brother (making you look bad too)"

I can tell nakulak has been it the trench before !! The emphasis here is on 'sent to everybody and their brother'.

You could hardly ever get rid of a Red Tag here, at least not before 6 months beyond the end of contract . . .

Paint was always part of the corrosion control process, no tape allowed, no contest . . .

Best Wishes
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Thanks Don,

I couldn't quite visualize the slip connection - that of course is what makes the fitting unsuitable for Division 1.

With regard to unions, I'm fairly certain (not absolutely sure) that all listed unions are also explosionproof. I did a random, but fairly large, sampling the other day and every clearly listed union was also explosionproof.
 
Status
Not open for further replies.
Top