You are absolutely correct. Your understanding is spot on!Here's a breakdown to reinforce your interpretation: The 10-Foot Rule and Seals

The requirement for a seal within 10 feet of the Class I, Division 1 boundary is to prevent the propagation of explosions or the transfer of flammable gases/vapors beyond the classified area.

The Restricted Conduit Section

The key part is the section of conduit between the seal and the boundary. This is the critical zone. The intent is to have a continuous, unbroken conduit run through this area. This is where the restriction on fittings applies.



After the Boundary

Once you are outside the classified area, the rules regarding conduit fittings relax. You are no longer bound by the same explosionproofing considerations. You can use standard fittings (like C bodies or LB fittings) for routing the conduit to the MCC.

In Summary

The restriction on fittings only applies to that portion of the conduit run that is between the seal-off fitting and the point where the conduit exits the Class I, Division 1 classified area.

Therefore, your statement

"After I am outside the boundary of the Class 1 area that pipe run could have a fitting like a C body or LB to go into my MCC... it is just that small section between the boundary and the sealoff in which I can not have the fitting not all the way back to the MCC?"

...is entirely correct!

Think of it this way: The seal is your firewall. The section of conduit leading up to the firewall must be as simple and robust as possible to prevent any leakage of gas/vapor before it reaches the seal. Once you've passed the seal and are outside the classified area, the risk of explosion propagation is significantly reduced (assuming the seal is properly installed and maintained). Flag for review