BOAF Interpretations

Interpretations Request Input

Original Request

Request ID: 8501
Requested By: Richard Mihalich
Requester E-Mail: rcmihalich@aol.com
Code Version: 2017
Code: NEC
Code Description:
Chapter: Chapter 1 General
Section: NEC Article. 250.92, Services
Topic: Bonding of Electrical Service Equipment
Question: Three questions are contained in the attached pdf along with background information. Here are the questions. Question #1 Is a service installation using standard locknuts and plastic bushings on 2” offset nipples connecting the meter enclosure to the service disconnect not sufficient for bonding under the requirements of 250.92? Question #2 Are the 2” offset nipples installed to connect the meter enclosure to the service disconnect required to be bonded according to the requirements of Article 250.92? Question #3 Are the bonding requirements for the service equipment including the first disconnecting means more stringent than the requirements for bonding after the first service disconnecting mean?
Comment: See the attached pdf
Attachment 1: Download

Existing Interpretations and/or Declaratory Statements Related to this request

Input Received:

1# Depends, if through a concentric knock out no it would not be sufficient, through a hole that is the correct size not concentric it would be sufficient.
2# yes if metallic, if pvc no, the connection through a non concentric hole would qualify as a good bond.
3#No, they are equivalent.

Andrew Bruhn on 01/19/2021 at 12:31 PM

!. Where is your stab? 2. Are we supposed to be able to download attached files? To my knowledge, we have not been able to do so in the past, 3. I agree with Andrew's response. 4. Happy New Year to you, too.

Joseph Belcher on 01/20/2021 at 8:51 PM

I agree with Andrew.

Jonathan Peer on 01/22/2021 at 12:11 PM

Answer:

#1. No. Read 250.92 (B) the last sentence which states "Standard locknuts or bushings shall not be the only means for the bonding required by this section but shall be permitted to be installed to make a mechanical connection of the raceway(s)." #2. If this is a service raceway, meaning it is before the means of overcurrent on the premises, yes. #3. Yes

On 01/25/2021 at 5:17 PM

Commentary:

The electrical code considers the service conductors, those that are are ahead of the first means of overcurrent protection as unprotected conductors. As such, the only way to shut those conductors off is, typically, by tripping the overcurrent on the transformer. That is why we have 2 tables in the electrical code. The bonding of raceways and equipment to the grounded conductor at the service is governed by table 250.102 (C)(1). This sizes conductors for the minimum grounded conductor brought to the service amongst other requirements. Table 250.122 is the table for sizing the equipment grounding conductor. This is different because this conductor only has to trip the defined overcurrent protective device (OCPD). Standard locknuts may be acceptable where there is an overcurrent device ahead of the items that may become energized. See section 250.97 for systems operating at over 250 volts.

Comments on Draft:

I agree with Doug.

Jonathan Peer on 01/25/2021 at 5:34 PM

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