Understanding Sub-Panels and Neutral Wires
By Dave Rongey - Summary:|
Electrical Panels with Neutral Wires and Ground Wires: Is it true that an un insulated neutral is not allowed to be used with the power feed cable for a sub-panel?
Sub-Panels Require a 4-Wire Cable with an Insulated Neutral
- The main line coming into my home and my fathers home from the power company transformer to my main box is not insulated.
- There are 3 wires from the pole twisted 2 insulated and one that is not.
- So is this a Double Standard where the power company can do whatever they want?
This electrical question came from: Greg, a Homeowner from Durham, North Carolina.
Thanks for your electrical wiring question Greg.
Wiring a Sub Panel with an Insulated Neutral and Separate Ground
Application: Wiring a Sub Panel.
Skill Level: Intermediate to Advanced – Best performed by a Licensed Electrical Contractor, Not Recommended for Homeowners.
Tools Required: Electricians pouch of hand tools and the various power tools necessary for installing the sub-panel.
Estimated Time: Depends on the type and size of the panel and available access to the project area.
Precaution: Any existing electrical wiring within the immediate area that may interfere with the installation of the sub panel should be identified and turned OFF and Tagged if necessary. Working in an electric panel is dangerous due to arc flash hazards and the possibility of electric shock.
Notice: Installing additional electrical wiring and a sub-panel should be done according to local and national electrical codes with a permit and be inspected.
Understanding Electrical Panels with Neutral Wires and Ground Wires
Greg, the panel that you are referring to is a Sub-Panel, not a Main Panel, and there is a Big Difference which I will explain with the following example:
- All single phase 240 volt Sub-Panels MUST have a 4-wire cable feed which must have a separate insulated neutral wire and a separate ground wire, which may be uninsulated.
- The neutral wire used with the Main Panel overhead service feed from the electrical utility company is most always un insulated as you and your father observed. If the Main Service feed was underground then the neutral wire would be required to be insulated.
- There is no Double Standard, and the power company cannot do whatever they want because they have electrical codes to follow as well. The only difference would be in some third world countries where they do not have established codes like we do here in the USA.
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- This information will help as you consider a Sub-Panel and its size.
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