A chart of if the sub-panel is wired properly. Produced by Charles Buell and Dylan Chalk

Use This Flow Chart To Get Them Right!

The way most home inspectors are trained to understand the difference between sub-panel wiring and main panel wiring is that once you have a sub-panel, the equipment grounds (green covered or bare wires) should be separated from the neutral conductors (the white ones) and the neutrals should not be bonded to the panel and would remain “floating,” while the grounds should be bonded to the panel. This is not a half-bad place to start the conversation, but unfortunately, sub-panels do not end there, and to think they all end there is to statistically be wrong at least 20% of the time.

Where I like to start with any sub-panel is determining if the sub or distribution panel is a three-conductor feed or a four-conductor feed. Once I determine this, I can go down a path to determine if it is correct or if it is wrong. To help illustrate this path, my friend and fellow home inspector Charles Buell built this flow chart to illustrate the circuitous path I take when inspecting a sub-panel. This is kind of a go/ no-go chart that can help you determine if the sub-panel in question is wired correctly or not.

Flow chart single phase

The color-coding of the chart is this:

Yellow = Proceed with caution

Red = Wrong – seek further investigation and repair by a licensed electrical contractor

Green – Good to Go

Please note that the chart also includes the required grounding system for detached buildings.

Check out this Video

To help you fully get your head around this flow chart, check out the video Charles Buell and I made. This video explains the flow chart works and also uses segments of Charlie’s 8-Hour Electrical Class to help you see why the sub-panels need to be wired this way.

Sub-Panel Video Link

One handy idea is to embed this flow chart write into your Scribeware template. This video here shows how I did this in Scrobeware. Now, when I’m on the job, this chart can just get recalled with a few clicks. The bottom line is ScribeWare can really help make you a smarter inspector.

Video showing the sub-panel flow chart built into the ScribeWare mobile app. 

Want to use this flow chart? Click here

Want to book Charlie or Dylan Chalk to present at your home inspection event? Reach out here.

By the way… Did you know ScribeWare’s mobile app is blazing fast and getting better all the time? Read about it here.

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