Wenatchee Home Inspections

Fused neutrals may have been common back in the day but is considered a no-no by today's standards unless used in a specific manner or motor applications.

There is many good reasons for this.  Having a circuit or device to appear to be electrically off while its components are electrically live to the line side can be dangerous.

When the neutral are fused and then opened in a manner that does not also open the line side you still have a circuit with current available and if you become the unlucky one to complete the circuit it can lead to shock or electrocution.

On a recent home inspection I came across an old 120v disconnect and when opening the disconnect I found that the branch circuit had a fused neutral.

I opened the blade disconnect and show that we only have voltage on the line side.

     



So let’s look at some of the history behind fused neutrals

Current standard-

2017 NEC

240.22 Grounded Conductor

No overcurrent device shall be connected in series with any conductor that is intentionally grounded, unless one of the following two conditions is met:

(1) The overcurrent device opens all conductors of the circuit, including the grounded conductor, and is designed so that no pole can operate independently.

(2) Where required by 430.36 or 430.37 for motor overload protection.

Back in 1962 we had the same version but different code section 1962 NEC 240.12.

It was in 1956 we get our code version that is much as it is today.

1956 NEC

2409- Grounded Conductor-
 No overcurrent device shall be connected in any permanently grounded conductor except as follows

1. Simultaneous Opening.  If overcurrent device simultaneously opens all conductor of the circuit

2. For motor-running protection as provided in sections 4326 and 4327

Back in 1951 we have the first requirement for not fusing the grounded conductor(neutral) uless used as in the exceptions.

1951 NEC


2409-
No overcurrent device shall be connected in any permanently grounded conductor except as follows

1. Simultaneous Opening.  If overcurrent device simultaneously opens all conductor of the circuit

2. B. Conductors of Branch Circuits. In locations where the conditions of grounding or the likelihood of reversal of connection warrants, the authority enforcing the code may require, on systems having a grounded neutral or having one side grounded, that the conductors of a 2-wire branch circuits shall have an overcurrent device in each conductor.

3. For motor-running protection as provided in sections 4326 and 4327

Prior to 1951 we have the restriction on fusing the grounded conductor only as it pertains to the service conductors. As you see in  article 2373 there is no restriction applied on the branch circuits.

1940 NEC

2371 (b.) Not in Grounded Conductor. No overcurrent device shall be inserted in a grounded service conductor except a circuit-breaker which simultaneously opens all conductors of the circuit.

2373. Location of Branch-Circuit Overcurrent Devices.
If the service overcurrent devices are locked or sealed, or otherwise not readily accessible, branch- circuit overcurrent devices shall be installed on the load side, shall be mounted in an accessible location and shall be of lower rating than the service over-current device.

So this get us pretty well all the way back to the early code and what was in force back then.

Though it once may have been allowed this is a safety concern and should upgraded to current requirements.

“Trouble is, kids feel they have to shock their elders and each generation grows up into something harder to shock.”

Ben Lindsey

If you find any errors or have additional information that would expand on any code, building standards or manufacturer requirements please let me know.

NCW Home Inspections, LLC  is a Licensed Washington State Home Inspection service located in Wenatchee Washington serving Chelan County, Douglas County, Kittitas County, Okanogan County and Grant County Washington and the cities of Wenatchee, Leavenworth, Cashmere, Oroville, Cle Elum, East Wenatchee, Quincy and many more…  

Your Wenatchee and Chelan Professional Real Estate, Home and Structural Pest Inspection Service

Instructor- Fundamentals of Home Inspection-  Bellingham Technical College

WA Home Inspector Advisory Licensing Board

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