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Page 26
d) The main device can be installed before the meter, between the meter and panel or
it can be part of the panel itself.
e) The most common installation is a combination circuit breaker panel, where the main
circuit breaker is located at the top or bottom of the panel.
f) If the main device is located before the panel, then turning it off will insure that there
are no energized parts in the panel.
g) If the main device is part of the panel, then turning the device off leaves the incoming
lugs of the main device still energized. In this case you really should have the MTU
and CT’s professionally installed.
h) Refer to Fig. A-2 (Page 29).
4) Understand the terminology.
a) Your service has two power conductors and one neutral conductor (grounded con-
ductor) coming in. The power wires are sometimes referred to as Line 1 and Line 2,
however in this manual we have referred to them as Phase A and Phase B.
b) The NEC and CEC sometimes refer to the neutral conductor as the grounded con-
ductor. This wire is always white, except for large conductors, which might be black
with a white band of phasing (marking) tape or in the case of service entrance cable
where it may be bare. Don’t confuse this with the “grounding” conductor, which is an
equipment ground and is either bare or green in color. At the main neutral bus of the
main device, the center tapped conductor of the main service is grounded to either
a ground rod or metal water pipe. Thus the neutral conductor is referred to as the
grounded conductor in the NEC and CEC.
c) 120 Volt loads such as receptacles and lights are connected between one of the
phase circuit breakers and the neutral bus and will have a single pole circuit breaker.
240 Volt loads are connected between Phases A and B and will have a two pole
circuit breaker. The MTU must be connected to a single pole 15 or 20A circuit breaker
(15 Amp in Canada) and the neutral bus.
d) The MTU transmits bits of data over the existing power lines to the electrical recep-
tacle that the RDU is plugged into.
e) Referring to Fig A-1 you can see that if the MTU is connected to Phase A and the
RDU is plugged into a receptacle on Phase A, then the data path is from the panel to
the receptacle. However if the MTU is on Phase A and the receptacle is on Phase B,
then the path is from the panel, out to the utility transformer, across the secondary
windings of the transformer, back to the panel and then to the receptacle. TED is not
designed to transmit all this way. It may work, but for consistent, reliable operation
you need to insure that they are both on the same phase.
5) How do I know if they are on the same phase?
a) Generally the phases alternate as they go down the panel. The circuit breakers on
the left side of the panel are usually numbered 1, 3, 5, 7, ...... and those on the right
hand side are numbered 2, 4, 6, 8 ...... . Generally circuit 1 will be Phase A, Circuit 3
A P P E N D I X A
D E T A I L E D I N S T A L L A T I O N I N S T R U C T I O N S
(Continued)
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