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December 1, 2020

Inspector’s Perspective

Field problems


Q – What are some Sealants Approved by NEC Code to keep rodents and water out.

A – NEC Article 227.8-spray foam insulation is not NEC approved. Ductseal is NEC  approved. Polywater is also acceptable.


Q – What is the interpretation of the New 2020  NEC Article 250.109 when it comes down to Bonding Metal Enclosures?

A – Metal enclosures are permitted to be used to connect bonding jumpers or equipment grounding conductors, or both, together to become a part of an effective ground-fault current path.


Code Change Summary: New code section permits a metal enclosure to serve as an effective ground-fault current path.

There are several examples in Article 250 of metal boxes and other enclosures being part of the effective ground-fault current path but until now, Article 250 has never officially recognized it.

  • NEC 250.110 requires enclosures of fixed equipment containing ungrounded conductors to be connected to an equipment grounding conductor.
  • Part V of Article 250 requires bonding to ensure electrical continuity and the capacity of an enclosure to conduct safely any fault current likely to be imposed on it.
  • Section 250.97 considers a metal raceway carrying a 277/480 circuit as properly bonded if it is connected to a box with listed fittings.

But what about the metal box itself? Is there any language in the NEC officially allowing a metal box or enclosure to be part of an effective ground-fault current path?

In the 2020 NEC, metal enclosures are now permitted to be used to connect bonding jumpers or equipment grounding conductors, or both, together to become a part of an effective ground-fault current path.

There were several similar public inputs (code change proposals) this cycle to recognize metal boxes and enclosures as an “equipment grounding conductor” by adding another line item to Section 250.118. This section provides a list of fourteen different items that are considered an “equipment grounding conductor”.

The new code language was placed in a new section and was worded carefully so as not to give the impression that a metal box or enclosure is technically an “equipment grounding conductor” since not all metal boxes or enclosures are listed as grounding and bonding equipment.

Q – Are local jurisdictions enforcing the 2020 addition to 230.71b

 A- Yes – Most jurisdictions started the adoption 8/1/2020 – Please see below references.


2017 Code Language:

230.71 Maximum Number of Disconnects.

(A) General. The service disconnecting means for each service permitted by 230.2, or for each set of service-entrance conductors permitted by 230.40, Exception No. 1, 3, 4, or 5, shall consist of not more than six switches or sets of circuit breakers, or a combination of not more than six switches and sets of circuit breakers, mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard or in switchgear. There shall be not more than six sets of disconnects per service grouped in any one location.

For the purpose of this section, disconnecting means installed as part of listed equipment and used solely for the following shall not be considered a service disconnecting means:

(1) Power monitoring equipment

(2) Surge-protective device(s)

(3) Control circuit of the ground-fault protection system

(4) Power-operable service disconnecting means

(B) Single-Pole Units. Two or three single-pole switches or breakers, capable of individual operation, shall be permitted on multiwire circuits, one pole for each ungrounded conductor, as one multipole disconnect, provided they are equipped with identified handle ties or a master handle to disconnect all conductors of the service with no more than six operations of the hand.