In reviewing Figure 240.144, it appears that "supply side of service bonding jumper" and "grounded conductor" have been combined.

Let us review how the NEC uses the terms "bonding" and "grounded conductor".

Atrticle 100 definitions "Bonding Jumper. A reliable conductor to ensure the required electrical conductivity between metal parts required to be electrically connected."

"Grounded Conductor. A system or circuit conductor that is intentionally grounded."

"Grounding Electrode Conductor. The conductor used to connect the grounding electrode(s) to the equipment grounding conductor, to the grounded conductor, or to both, at the service, at each building or structure where supplied by a feeder(s) or branch circuit(s) or at the source of a separately derived system.

Article 250.24(C) Grounded Conductor Brought to Service Equipment "Where an AC system operating at less that 1000 volts is grounded at any point, the grounded conductor(s) shall be run to each service disconnecting means enclosure. The grounded conductor shall be installed in accordance with 250.24(C) (1) through (C)(3)"

Article 250.24(C)(1) Routing and sizing "This conductor shall be routed with the phase conductors and shall not be smaller than the required rounding electrode conductor specified in Table 250.66...In addition, for service-entrance phase conductors larger than 1100kcmil copper or 1750kcmil aluminum, the grounded conductor shall not be smaller than 12 1/2 percent of the area of the largest service-entrance conductor."

Revisit the first sentence of 250.102(C) "Bonding jumpers for service raceways..." This is requiring service entrance raceways to be bonded to the service entrance enclosure.

The Figure indicates a grouded conductor being routed with the service entrance conductors. The bonding jumper for this Figure should have been drawn as in Figure 250.45 where the bonding jumper is connected to the raceways and to the enclosure. The conductor in Figure 250.144 identified as the service side grounding bonding jumper should be identified as the grounded conductor.

Mike: We have looked and looked in the NEC and your Grd/Bond book but can not find these is answers. Installation: multiple PVC feeders with aluminum conductors installed within an utility tunnel with metallic pull boxes, 200A maximim apartment panel feeders, no parallel feeders, each feeder has an aluminum conductors and aluminum equipment ground conductors installed. Per code if the equipment ground is spliced with these pull/junction boxes the conductor needs to be bonded to the box. The feeder breaker sizesl; 110A, 175A and 200A. Question One...What size copper bond connection to the box from the equipment ground wire splice? Question Two...Splice via Cp/Al split bolt? Question Three...What size single bond wire required to interconnect the metallic pull boxes? Question Four...Install the metallic pull box bond conductor in conduit between the boxes or bare conductor outside the pull boxes? Thank you for your help. Tom

Mike, Could you tell me something about the earth connection of the transformer lightning arrester in fig. 250-148 ? Thank you for you help

I don't think a bonding bushing is the appropriate way to terminate/bond an isolated conduit running down a pole since a weatherhead really needs to be installed at this location. Will an external conduit clamp suffice? This certainly is not as pretty an installation as illustrated in figure 250-148, but it is better than filling the conduit run with rain water.

Good illustration, though I would like to see the code refererences for a new construction and installation for a 4-wire clothes dryer circuit.