Panel Replacement in an Older Ungrounded Dwelling
A 1958 single-family house has a 100 A fuse panel, two-wire ungrounded NM cable, and a 30 A, 240 V dryer receptacle. The owner hires a licensed electrician to replace the panel with a 200 A panel and install AFCI/GFCI breakers. The service is overhead with 2/0 copper. During inspection, the electrician finds: the bathroom receptacle has no equipment ground and is fed by old 2-wire cable; kitchen counter receptacles are on two 20 A circuits with no GFCI; the dryer receptacle is a 3-wire 10-30R fed by 10/2 NM cable with the bare conductor used as both neutral and ground; and the laundry receptacle is ungrounded. The electrician proposes to replace the bathroom and laundry receptacles with GFCI receptacles marked 'No Equipment Ground,' replace the kitchen receptacles with GFCI receptacles, and keep the 3-wire dryer receptacle. The AHJ enforces the adopted NEC.
1. Are the proposed GFCI replacements for the ungrounded bathroom, laundry, and kitchen receptacles acceptable? What labeling and limitations apply?
Read the worked answer
Yes, with conditions. 406.4(D)(2) permits replacing a receptacle on an existing ungrounded branch circuit with a GFCI receptacle, but the receptacle must be marked 'GFCI Protected' and 'No Equipment Ground,' and the GFCI does not create an equipment grounding conductor. The bathroom and laundry receptacles are in locations requiring GFCI under 210.8(A); the kitchen counter receptacles also require GFCI. If the electrician only replaces the receptacles, the lack of an EGC can be handled by the GFCI and labeling. If the circuit is extended, new cable is run, or a new receptacle outlet is added, an EGC must be provided. Do not connect the GFCI grounding terminal to the neutral or to a remote ground unless a compliant EGC exists. Test and label downstream receptacles.
2. Evaluate the 3-wire dryer receptacle. Can it remain after the service and panel replacement?
Read the worked answer
The 3-wire dryer receptacle can remain only as an existing installation under 250.140, and only if all conditions are met: the branch circuit is 3-wire with no EGC, the neutral is not smaller than 10 AWG Cu, the receptacle is a 10-30R, and the dryer is listed for the 3-wire connection. Replacing the service panel does not by itself convert the dryer branch circuit to new work, so the existing exception may still apply. However, using the bare conductor as both neutral and ground is not permitted for any new or extended circuit, and a new dryer branch circuit requires a 4-wire receptacle with separate neutral and EGC. Also check 210.8(A) for laundry-area GFCI; a 2-pole GFCI breaker may be required. If the dryer is replaced with a 4-wire unit or the circuit is altered, install a 4-wire circuit.
3. What grounding and bonding checks are required for the service replacement?
Read the worked answer
The service replacement must establish a complete grounding electrode system and main bonding jumper. Verify the GEC is sized per 250.66 for the 2/0 Cu service, connect it to the water pipe if it qualifies and to a supplemental electrode, bond the water piping and gas piping, and ensure the panel neutral bar is bonded to the enclosure only at the service. Confirm the equipment grounding conductor for every feeder and branch circuit is continuous, and that no subpanel has a neutral-to-ground bond. Check the dryer circuit, the new AFCI/GFCI breakers, and the grounding of the laundry and bathroom receptacles. The AHJ should inspect the bonding and grounding before the panel is energized.