This article is intended to provide guidance to wiring a ZEFNET wallmounted EVSE.

Materials Required:

Junction Box

Double Pole Breaker (40A/50A/60A/80A/100A)

Materials Provided with EVSE:



Lag bolt spacers

Plug Socket

Plug Socket attachment screws

Power Requirements:

208v or 240v - L1 + L2 + GND

Installation - Service Connections

Only 3 wires are connected, but care must be taken that the service transformer secondary connection is definitely known, and the 3 wires from the main circuit breaker panel are connected and labeled correctly. Figures 1, 2, and 3 show the most common service transformer secondary wiring formats.

Notice that L1, L2, & Ground are labeled on each diagram. Those transformer outputs correspond to the same inputs on the ZEFNET HCS charger. Also, each of the two 3-phase diagrams shows an L3 output, which is not used. Do not connect all three phases of a 3-phase secondary to the ZEFNET HCS charger. This is a single-phase device.

The Neutral at the service panel must be connected to Earth Ground somewhere in the system on any of the three connection arrangements. Ground-fault protection is not possible unless the Neutral (center-tap on the service transformer) is connected to an Earth Ground. If no Ground is provided by the electrical service, a grounding stake must be driven into the Ground nearby, following local electrical codes. The grounding stake must be connected to the ground bar in the main breaker panel, and Neutral connected to Ground at that point.

Figure 1: 220/240V Single Phase

Figure 2: 208V Three Phase, Wye Connected

Figure 3: 240V Three Phase, Delta Connected, w/Center-Tap on One Leg

CAUTION: With the delta connection, one leg must be center-tapped. Only the two phases on either side of the

center tap can be used. The two phases must both measure 120V to Neutral. The third line (L3) of the delta is 208V, with respect to Neutral, and is sometimes referred to as a “stinger”. Do not use this third line! Consult the transformer manufacturer’s literature to be sure the single leg can supply the required power.