225.27 Raceway Seal.

Questions the inspector may have: Are the parallel raceways above the transformer feeding or supplied by the exterior panelboard? If the exterior panelboard is on the secondary side of the transformer, does it have a main OCPD that provides secondary overcurrent protection for the transformer? If the exterior panelboard supplies the transformer, where is the required secondary overcurrent protection for the transformer and is it located close enough to comply with the rules in NEC 240.21(C)? Securing of the liquidtight flexible metal conduit? Are pipe bollards needed for protection?
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Questions the inspector may have: Are the parallel raceways above the transformer feeding or supplied by the exterior panelboard? If the exterior panelboard is on the secondary side of the transformer, does it have a main OCPD that provides secondary overcurrent protection for the transformer? If the exterior panelboard supplies the transformer, where is the required secondary overcurrent protection for the transformer and is it located close enough to comply with the rules in NEC 240.21(C)? Securing of the liquidtight flexible metal conduit? Are pipe bollards needed for protection?

Code Change Summary: Clarifications were made regarding the sealing of raceways.

The previous code language required raceways to be sealed as they enter a building if they were part of an underground distribution system. Now, raceways that are outside in general, must be sealed where they enter the building.

Note that the code language is not exclusive to below grade raceways. The new code language will apply to any exterior raceway that contains feeders and enters the building.

One example is a fused disconnect switch mounted outside the building adjacent to an air conditioner. If the raceway containing the feeder (supplying the fused disconnect switch) penetrates the building, then it must be sealed, even if there is no temperature difference from outside to inside. The other rule for raceway sealing in 300.7(A) only applies when portions of a raceway or sleeve are known to be subjected to different temperatures, and where condensation is known to be a problem.

The main intent of the code change is to always have measures in place so that moisture doesn’t enter electrical enclosures through the connected raceways.

Below is a preview of Article 225. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2017 NEC® edition of NFPA 70.

2014 Code Language:

225.27 Raceway Seal. Where a raceway enters a building or structure from an underground distribution system, it shall be sealed in accordance with 300.5(G). Spare or unused raceways shall also be sealed. Sealants shall be identified for use with the cable insulation, conductor insulation, bare conductor, shield, or other components.

2017 Code Language:

225.27 Raceway Seal. Where a raceway enters a building or structure from outside, it shall be sealed. Spare or unused raceways shall also be sealed. Sealants shall be identified for use with cable insulation, conductor insulation, bare conductor, shield, or other components.

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225.27 Raceway Seal.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Which of the following raceways must be sealed?

A: A feeder raceway installed above a suspended ceiling.
B: All branch circuit raceways connected to junction boxes.
C: An interior feeder raceway entering a panelboard.
D: An exterior feeder raceway entering a building.
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