Residential Service Change

J

Jimmy7

Senior Member
Location
Boston, MA
Occupation
Electrician
I have to change a 100 amp overhead service for an elderly relative. The panel is in the finished sheetrocked basement. The three wire range and dryer are on the first floor. We’re going on the 2026 code here in Massachusetts. What is the best way to do this service when three wire appliances are involved? Do I have to try to snake both a new range and dryer cable? Everything is finished, so snaking would be difficult.
 
Depends on what existing wiring method you have;
What I have found in my area is old NM with no bare wire, I use NEC 250.130(C) that allows running a separate EGC to a outlet, sometimes I can run green #10 solid from the panel and hit both receptacles. A old T25 phone cable stapler works well for #10. Then update the appliances to 4-wire.
The last time I ran into this the original installer had actually had installed a 8/3 WG and cut off the bare wire, I was able to get enough eek slack and pigtail.
 
infinity said:
That won't help because the new panel is going to be a sub-panel not the service.
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I think they actually changed the wording slightly in 2023 (B) to allow leaving them be, even off a sub panel as long as the neutral is fully insulated.
250.140(B)(5) even allows a SE cable to have the bare insulated, I'd probably use heat shrink in that case.
 
tortuga said:
I think they actually changed the wording slightly in 2023 (B) to allow leaving them be, even off a sub panel as long as the neutral is fully insulated.
250.140(B)(5) even allows a SE cable to have the bare insulated, I'd probably use heat shrink in that case.
Click to expand...
Could be. He said under the 2026 is that the same as the 2023?
 
infinity said:
Could be. He said under the 2026 is that the same as the 2023?
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tortuga said:
Pretty much I think the only change in the 2026 is they made was editorial.
Click to expand...

That is correct. They simply added more specific references to 250.140(B)(1) through (5)


That section in 2026 is written as follows:

(B) Grounded Conductor Connections.

For existing branch-circuit installations only, if an equipment grounding conductor is not present in the outlet or junction box the frame of the appliance shall be permitted to be connected to the grounded conductor if all the conditions in the following list items 250.140(B)(1), 250.140(B)(2), and 250.140(B)(3) are met and the grounded conductor complies with either list item 250.140(B)(4) or 250.140(B)(5):
The supply circuit is 120/240-volt, single-phase, 3-wire; or 208Y/120-volt derived from a 3-phase, 4-wire, wye-connected system.

The grounded conductor is not smaller than 10 AWG copper or 8 AWG aluminum or copper-clad aluminum.

Grounding contacts of receptacles furnished as part of the equipment are bonded to the equipment.

The grounded conductor is insulated, or the grounded conductor is uninsulated and part of a Type SE service-entrance cable and the branch circuit originates at the service equipment.

The grounded conductor is part of a Type SE service-entrance cable that originates in equipment other than a service. The grounded conductor shall be insulated or field covered within the supply enclosure with listed insulating material, such as tape or sleeving to prevent contact of the uninsulated conductor with any normally non-current-carrying metal parts.
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I struggle with the wording on #4. Am I to read that as the following two scenarios

1a. The grounded conductor is insulated and the branch circuit originates at the service equipment.

2a. The grounded conductor is uninsulated and part of a Type SE service-entrance cable and the branch circuit originates at the service equipment.

Or am I to instead read it as these two alternatives?

1b. The grounded conductor is insulated (may originate from the service equipment, OR MAY ORIGINATE FROM SUB PANEL)

2b. The grounded conductor is uninsulated and part of a Type SE service-entrance cable and the branch circuit originates at the service equipment.

Rob G
Seattle
 
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