Volume Argument

[mattatouie]

We've been doing work for a gas compression company for quite some time. Recently, their master electrician brought up the volume of the enclosure in relation to seal-off location... I attached a pic for reference, the actual installation is rotated 90 deg clockwise, i'm not sure how to do that. I know the installation pictured meets 2017 NEC. The question is; Does the presence of the ELBY between the seal-off and the device add enough volume that this is not a safe installation? We haven't found any factory spec that says to seal it or not to seal it, so we're sealing it. It's in a Class 1, Div 2 location. Thanks y'all

 

[rbalex]

The relevant text to Section 501.15(A)(1) was modified in the 2017 NEC to reflect concerns of the volume of conduit bodies:

...
Conduit seals shall be installed within 450 mm (18 in.) from the enclosure or as required by the enclosure marking. Only explosionproof unions, couplings, reducers, elbows, and capped elbows that are not larger than the trade size of the conduit shall be permitted between the sealing fitting and the explosionproof enclosure.

That said, the installation indicated is nevertheless acceptable.

IMO, from years of successful industry practice, conduit bodies that met the previous verbiage should be acceptable too.

 

[romex jockey]

It's been a while since i did any expolosionproof installs, but iirc we would install the next size up seal w/ex-pf bushings to have it meet the same pipe fill as the raceway ~RJ~