Re: Three phase panel question
Here is Art. 455 from the 2011 NEC.
I. General
455.1 Scope. This article covers the installation and use of
phase converters.
455.2 Definitions.
Manufactured Phase. The manufactured or derived phase
originates at the phase converter and is not solidly connected
to either of the single-phase input conductors.
Phase Converter. An electrical device that converts singlephase
power to 3-phase electric power.
Informational Note: Phase converters have characteristics
that modify the starting torque and locked-rotor current of
motors served, and consideration is required in selecting a
phase converter for a specific load.
Rotary-Phase Converter. A device that consists of a rotary
transformer and capacitor panel(s) that permits the operation
of 3-phase loads from a single-phase supply.
Static-Phase Converter. A device without rotating parts,
sized for a given 3-phase load to permit operation from a
single-phase supply.
455.3 Other Articles. Phase converters shall comply with
this article and with the applicable provisions of other articles
of this Code.
455.4 Marking. Each phase converter shall be provided
with a permanent nameplate indicating the following:
(1) Manufacturer’s name
(2) Rated input and output voltages
(3) Frequency
(4) Rated single-phase input full-load amperes
(5) Rated minimum and maximum single load in kilovoltamperes
(kVA) or horsepower
(6) Maximum total load in kilovolt-amperes (kVA) or
horsepower
(7) For a rotary-phase converter, 3-phase amperes at full load
455.5 Equipment Grounding Connection. A means for attachment
of an equipment grounding conductor termination in
accordance with 250.8 shall be provided.
455.6 Conductors.
(A) Ampacity. The ampacity of the single-phase supply conductors
shall be determined by 455.6(A)(1) or (A)(2).
Informational Note: Single-phase conductors sized to prevent
a voltage drop not exceeding 3 percent from the source
of supply to the phase converter may help ensure proper
starting and operation of motor loads.
(1) Variable Loads. Where the loads to be supplied are
variable, the conductor ampacity shall not be less than
125 percent of the phase converter nameplate single-phase
input full-load amperes.
(2) Fixed Loads. Where the phase converter supplies specific
fixed loads, and the conductor ampacity is less than
125 percent of the phase converter nameplate single-phase
input full-load amperes, the conductors shall have an ampacity
not less than 250 percent of the sum of the full-load,
3-phase current rating of the motors and other loads served
where the input and output voltages of the phase converter
are identical. Where the input and output voltages of the
phase converter are different, the current as determined by
this section shall be multiplied by the ratio of output to
input voltage.
(B) Manufactured Phase Marking. The manufactured
phase conductors shall be identified in all accessible locations
with a distinctive marking. The marking shall be consistent
throughout the system and premises.
455.7 Overcurrent Protection. The single-phase supply
conductors and phase converter shall be protected from
overcurrent by 455.7(A) or (B). Where the required fuse or
nonadjustable circuit breaker rating or settings of adjustablenonadjustable circuit breaker rating or settings of adjustable
circuit breakers do not correspond to a standard rating or
setting, a higher rating or setting that does not exceed the
next higher standard rating shall be permitted.
(A) Variable Loads. Where the loads to be supplied are
variable, overcurrent protection shall be set at not more than
125 percent of the phase converter nameplate single-phase
input full-load amperes.
(B) Fixed Loads. Where the phase converter supplies specific
fixed loads and the conductors are sized in accordance
with 455.6(A)(2), the conductors shall be protected in accordance
with their ampacity. The overcurrent protection determined
from this section shall not exceed 125 percent of the
phase converter nameplate single-phase input amperes.
455.8 Disconnecting Means. Means shall be provided to
disconnect simultaneously all ungrounded single-phase
supply conductors to the phase converter.
(A) Location. The disconnecting means shall be readily
accessible and located in sight from the phase converter.
(B) Type. The disconnecting means shall be a switch rated
in horsepower, a circuit breaker, or a molded-case switch.Where only nonmotor loads are served, an ampere-rated
switch shall be permitted.
(C) Rating. The ampere rating of the disconnecting means
shall not be less than 115 percent of the rated maximum
single-phase input full-load amperes or, for specific fixed
loads, shall be permitted to be selected from 455.8(C)(1) or
(C)(2).
(1) Current Rated Disconnect. The disconnecting means
shall be a circuit breaker or molded-case switch with an
ampere rating not less than 250 percent of the sum of the
following:
(1) Full-load, 3-phase current ratings of the motors
(2) Other loads served
(2) Horsepower Rated Disconnect. The disconnecting
means shall be a switch with a horsepower rating. The
equivalent locked rotor current of the horsepower rating
of the switch shall not be less than 200 percent of the
sum of the following:
(1) Nonmotor loads
(2) The 3-phase, locked-rotor current of the largest motor
as determined from Table 430.251(B)
(3) The full-load current of all other 3-phase motors operating
at the same time
(D) Voltage Ratios. The calculations in 455.8(C) shall apply
directly where the input and output voltages of the phase converter
are identical. Where the input and output voltages of the
phase converter are different, the current shall be multiplied by
the ratio of the output to input voltage.
455.9 Connection of Single-Phase Loads. Where singlephase
loads are connected on the load side of a phase converter,
they shall not be connected to the manufactured phase
455.10 Terminal Housings. A terminal housing in accordance
with the provisions of 430.12 shall be provided on a
phase converter.
II. Specific Provisions Applicable to Different Types of
Phase Converters
455.20 Disconnecting Means. The single-phase disconnecting
means for the input of a static phase converter shall be
permitted to serve as the disconnecting means for the phase
converter and a single load if the load is within sight of the
disconnecting means.
455.21 Start-Up. Power to the utilization equipment shall
not be supplied until the rotary-phase converter has been
started.
455.22 Power Interruption. Utilization equipment supplied
by a rotary-phase converter shall be controlled in such
a manner that power to the equipment will be disconnected
in the event of a power interruption.
Informational Note: Magnetic motor starters, magnetic contactors,
and similar devices, with manual or time delay restarting
for the load, provide restarting after power interruption.
455.23 Capacitors. Capacitors that are not an integral part
of the rotary-phase conversion system but are installed for a
motor load shall be connected to the line side of that motor
overload protective device.
This is just my opinion but for marking the manufactured leg, I prefer to use orange just like what would be used for the high leg of 240V delta.
Disregard the green wire, it has no bearing on this project.
I use is a must and requires every bit of it to start.