What Electrical System Is It?
•
•
•
•
Based on secondary side of upstream transformer, NOT by how load is connected.
Most SPD/TVSS order errors are misunderstandings related to grounding or neutrals.
What
Electrical
System
Is It?
Grounded system means that the system
is referenced
toElectrical
ground,
NOT
that
there
Based on secondary sideWhat
of upstream
transformer, NOTSystem
by how load is connected
Is
It? is a safety ground.
Most
SPD/TVSS
misorders
are
misunderstandings
related
to
grounding
or neutrals
What Electrical System
By convention, ground wires are notBased
‘counted’
of
the
wires
(3-wire,
4-wire,
What
Electrical
System
It? etc.).
on secondaryas
sideone
of upstream
transformer,
NOT
by
how load
isIs
connected
Grounded system means that the system is referenced to ground, NOT that there is a safety ground
Based
secondary
side of upstream transformer, NOT by how lo
on secondary
side
ofmisunderstandings
upstream
transformer,
NOT
howon
load
connected
MostBased
SPD/TVSS
misorders
areare
toby
grounding
orisneutrals
By
convention,
ground wires
not ‘counted’
as one related
of the
wires
(3-wire,
4-wire,
etc.)
Most
SPD/TVSS
misorders
are misunderstandings
related to grou
Most SPD/TVSS
misorders
are
misunderstandings
to grounding
neutrals
Grounded
system means
that the
system
is referenced related
to ground,
NOT that or
there
is a safety
ground
Grounded
system
means
that the system is referenced to ground,
Grounded
means
thatnot
the‘counted’
system isas
to
ground,
NOT4-wire,
that there
A are
Breferenced
B system
By convention,
ground
wires
one
of
the
wires
etc.)
A (3-wire,
Bis a safety ground
3-phase 4-wire Grounded Wye
A
3-phase 4-wire Grounded Wye
By wires
convention,
ground
wires
By convention, ground wires are not ‘counted’ as one of the
(3-wire,
4-wire,
etc.)are not ‘counted’ as one of the wires
Neutral bonded to ground. Neutral pulled into
NeutralA bondedWhat
to ground.Electrical
Neutral
NOT pulled
into
A
B
B
System
Is
A
N
AIt? B
B
A
B
N
A
B
A
B
N
B
facility. Common system configurations.
facility. Common
system configurations
MCC,
Based on secondary
side
of upstream
transformer, at
NOT
byAhow load is connected
What Electrical
System
Is It?
V = 120V (208Y/120V) APT ‘2’ Based on secondary side of upstream transformer,
Most SPD/TVSS
misorders
are
misunderstandings related to grounding or neutrals
andiswater
treatment.
NOTpumping
by how
load
connected
N
N
N
V
V
V
N
related
to 120V
grounding
or neutrals
N G to ground, NOT
Grounded
system
means
that
theNsystem
thatN there is a safety ground
G (208Y/120V)
G misunderstandings
V = 277V (48OY/277V) APT ‘4’ Most SPD/TVSS misorders are
V=
APT
‘2’is referenced
N
Grounded system means that the systemBy
is referenced
to ground,
NOT
thatare
there
is a‘counted’
safety ground
What Electrical S
convention,
ground
wires
not
as
one
of
the
wires
(3-wire,
4-wire,
etc.)
C
C
C
V = 347V (600Y/347V) APT ‘8’ By convention, ground wires are not ‘counted’
277V
(48OY/277V)
APT ‘4’
as one of V
the=wires
(3-wire,
4-wire, etc.)
Based
on secondary
side of upstream transformer, NO
3-phase 4-wire Grounded Wye
3-phase 4-wire
Ungrounded
Wye
3-phase 4-wire Grounded Wye
bonded to ground
Neutral(600Y/347V)
bonded to ground APT
Neutral
ground G V misorders are misunderstandings
V = 127V (220Y/127V) APT ‘21 ‘ (non-USA)
V NOT bonded
V
Mostto SPD/TVSS
rela
V
V = 347V
G Neutral
G
V B
V
A pulled into facilityVG V‘8’
B Neutral mayGor may
A
G not beA
Neutral
NOT
pulled into facility
B is referenced
G pulled into facility
ANeutral
B
A
Grounded
system means that the system
AG system configuration at MCC, B
Common system configuration
Rare system configuration; Error/miss-wire?
Common
V = 220V (38OY/220V)
APT ‘7’ (non-USA)B
V = 127V
(220Y/127V)
APT
‘21 ‘Electrical
(non-USA)
C
Cwires are not ‘counted’ as one o
C C Is It?
What
System
C
By
convention,
ground
V = 120V C(208Y/120V)
APT
‘2’
Note
NEC
285.3(2),
pumping
and
water
treatment
C
C
V = 277V (480Y/277V) APT ‘4’
V = 120V
(208Y/120V)
Rare
- Call
V on
= 120V
(208Y/120V)
APT
‘2’
3-phase
4-wire
Grounded
Wye
3
3-phase
4-wire
secondary
side
of
upstream
transformer,
NOT
by
how
load
is connected
V Based
= 220V
(38OY/220V)
APT
‘7’Wye
(non-USA)
3-phase
4-wire
Grounded
Wye
3-phase
4-wire
Grounded
Wye
3-phase
4-wire
Ungrounded
WyeGrounded Wye
3-phase
4-wire
Grounded
Wye
4-wire
Ungrounded
4-wire
Grounded
V = 347V
(600Y/347V)
APT ‘8’
(480Y/277V)
APTNeutral
‘5’
V =3-phase
277V (480Y/277V)
APT ‘4’bonded
Neutral
to ground V = 277V 3-phase
bonded toWye
ground
N
N
Neutral
bonded
to ground
Neutral
bonded
to
ground
Neutral
NOTto
bonded
A
A
B to
SPD/TVSS
misorders
are
misunderstandings
grounding
neutrals
V = 127V
(220Y/127V)
(600Y/347V)
APT
‘9’ground
V =Neutral
347V
(600Y/347V)
APTN
‘8’
Neutral
bonded
toNground APT ‘21’ (non-USA) Most
bonded
to ground
Neutral
NOT
bonded
to or
ground
Neutral
into facility V = 347Vrelated
Neutral
NOT
pulled into facility
Npulled
N
N
Neutral
pulled
into facility
Neutral
NOT
pulled
into Common
facility
Neutral
may
or may
not
be
into into
facility
V = 220V
(380Y/220V)
V = 127V
(220Y/127V)
(non-USA)
V =Neutral
127V
(220Y/127V)
APT
‘21’the
(non-USA)
Neutral
pulled
into facility APT ‘7’ (non-USA) Grounded
NOT
pulled
into
facility
Neutral
may
orCall
may
notpulled
be system
pulled
facility
system
means
that
system
is referenced
to ground,
NOT
that
there
is a
safetyatground
system
configuration
Common
configuration
MCC,
What Electrical System Is It?
B
N
R
V = 220V
V =Common
220Vsystem
(380Y/220V)
APT ‘7’at(non-USA)
(380Y/220V)
Call (non-USA)
Common
system
configuration
RareRare
system
configuration;
Error/miss-wire?
Common
configuration
Electrical
System
Common
system
configuration Is It? 3-phase
system
configuration;
Error/miss-wire?
system
configuration
at MCC,
Resistive or Impedance GroundedWhat
Wye
4-wire
Ungrounded
Wye
V = 120V
(208Y/120V)
‘2’
N
pumping
and
wateretc.)
treatment
By convention,
ground
wires
areMCC,
not
‘counted’
oneload
of the
(3-wire,
4-wire,
Based
on secondary
side
ofand
upstream
NOT APT
byashow
iswires
connected
V = 120V
(208Y/120V)
APT
‘2’
NoteNote
NECNEC
285.3(2),
water
treatment
V = 120V
(208Y/120V)
APT
pumping
and water
treatment
Vtransformer,
= 277V (480Y/277V)
APT
‘4’
V
V = 120V (208Y/120V) APT ‘2’N
B‘2’ is connected pumping
Based on secondary side of upstream
transformer,
NOT by
how
load
A 285.3(2),
N
V
=
277V
(480Y/277V)
APT
‘4’
V
=
120V
(208Y/120V)
Rare
Call
V
=
120V
(208Y/120V)
APT
‘2’
Neutral bonded to ground
via
grounding
resistor.
Neutral
NOT
bonded
to
ground.
Neutral
mayor
V
=
277V
(480Y/277V)
APT
‘4’
V
=
120V
(208Y/120V)
Rare
Call
V
=
120V
(208Y/120V)
APT
‘2’
V
=
347V
(600Y/347V)
APT
‘8’
V
V
=
277V
(480Y/277V)
APT
‘4’
A
Most
SPD/TVSS
misorders
are
misunderstandings
related
to
grounding
or
neutrals
V
V
Most SPD/TVSS V
misorders are misunderstandings
related to A
grounding
or neutrals
A
G
G
B = 277V
B = (non-USA)
V = 347V
(600Y/347V)
APT ‘8’
V
277V
(480Y/277V)
APTAPT
‘5’(600Y/347V)
V = 277V
(480Y/277V)
APT
‘4’ (220Y/127V)
B
VG
= 347V
(600Y/347V)
APT
‘8’
V = 277V
(480Y/277V)
‘5’
VA=
127V
APT ‘21’
V
V
(480Y/277V)
APT
‘4’ V
VA= 347V
APT
‘8’
V
V
G
Grounded
system
means
that
the
system
is
referenced
to
ground,
NOT
that
there
is
a
safety
ground
Grounded
system
means
that
the
system
is
referenced
to
ground,
NOT
that
there
is
a
safety
ground
V
G
GV = 127V
Neutral may, or may not, be pulled
into
facility.
may
not
be
pulled
into
facility.
Rare
system
V
=
220V
(380Y/220V)
APT
‘7’
(non-USA)
V
V
=
127V
(220Y/127V)
APT
‘21’
(non-USA)
(220Y/127V)
APT(non-USA)
‘21’ (non-USA)
V
=
347V
(600Y/347V)
APT
‘9’
V
= 347V
(600Y/347V)
APT
‘8’
V = 127V
(220Y/127V)
APT ‘21’
V
=
347V
(600Y/347V)
APT
‘9’
V
= 347V
(600Y/347V)
APT
‘8’
V
C
By convention,
ground wires are not
as (380Y/220V)
oneCof the
(3-wire,
4-wire,
etc.)
Bywires
convention,
ground
are (220Y/127V)
notC ‘counted’
of the wires
4-wire,
etc.)
V
V = 220V
(380Y/220V)
V = 220V
APT(non-USA)
‘7’ (non-USA)
V =(3-wire,
127V
(220Y/127V)
Call
(non-USA) APT ‘7’ (non-USA)
V = 127V
‘21’one
(non-USA)
V =‘counted’
220V
(380Y/220V)
APT
‘7’
V = 127V
(220Y/127V)
Call
(non-USA)
V = wires
127V
(220Y/127V)
APT APT
‘21’ as
(non-USA)
N
Becoming popular3-phase
system4-wire
on high-tech
applications.
configuration;
Error/miss-wire?.
Note
NEC
285.3(2).
C
V(380Y/220V)
V
N Ungrounded
CAPT APT
C Grounded Wye
Grounded Wye
3-phase
4-wire
3-phase 4-wire
V = 220V
V = 220V
(380Y/220V)
‘7’ Wye
(non-USA)
G
G
V = 220V
V = 220V
(380Y/220V)
‘7’ (non-USA)
(380Y/220V)
Call Call
(non-USA)
N(non-USA)
B
Neutral bonded to ground
Neutral bonded
to ground
Neutral
A
B
N
A
B NOT bonded to ground
R B Grounded
A
3-phase
4-wire
3-phase
4-wire Ungrounded
Grounded
Wye
V = 120V (208Y
/120V)
Rare
Call APT A
V =N120V
(208Y/120V)
- Call
BB
ANeutral
A 3-phase
B APT
C Wye
C
B Wye
A
B
Neutral
pulled
into -facility
NOT pulled
into facility
Neutral
may or 4-wire
mayAnotRare
be
pulled
into
facility
A A
V
G
Ato ground
Neutral
bonded
to ground
Neutral
bonded
Neutral NOT bonded
to ground
A
Common system configuration
Rare
system
configuration;
Error/miss-wire?
Common
system
configuration
at
MCC,
A
3-phase
4-wire
Grounded
Wye
3-phase
4-wire Grounded Wye
A
V = 277V (48OY/277V)
APT
‘5’
V
=
277V
(48OY/277V)
APT
‘5’
G
V
Neutral
pulled
intowater
facility
Neutral
NOT pulled into facility
Neutral may orVmay
not bonded
be pulled
into facility
V = 120V (208Y/120V) APT ‘2’
Note
NEC 285.3(2),
and
treatment
Neutral bonded to ground
Neutral
to ground
N pumping
G
C
N
V = 277V APT
(480Y/277V)
120V (208Y/120V)
Rare
-VCallNeutral
V = 120V
(208Y/120V)
B GAPT
V N V =Common
V into facility
VError/miss-wire?
pulled
Neutral NOT
pulled into facility
G V configuration;
Common
system
configuration
Rare system
system
configuration
at MCC,
GAPT ‘2’
V = 347V (600Y/347V)
‘9’ APT ‘4’
V = 347V
(600Y/347V)
V ‘9’
N
Single-Phase
N
V = 347V (600Y/347V) APT ‘8’
V
=
277V
(480Y/277V)
APT
‘5’
V
=
277V
(480Y/277V)
APT
‘4’
Common system configuration Note NEC 285.3(2),
Common system configuration at MCC,
V = 120V
(208Y/120V)
APT
‘2’
pumping
and water treatment
N
N
Resistive
or
Impedance
Grounded
Wye
Split-Phase
‘Single-Phase’
Verify
where
Neutral
and
Ground
are!
V = 127V (220Y/127V) APT ‘21’ (non-USA)
V = (220Y/127V)
347V (600Y/347V)
‘9’C (non-USA)
V = 347V (600Y/347V) APT ‘8’
NCall
C pumping and water treatment
V = 120V (208Y/120V) APT ‘2’ N N
C
V = 127V
APT
RAPT
N
V = 277V
(480Y/277V)
‘4’
V = of120V
V bonded
= 120V
(208Y/120V)
APT
‘2’ Often for one leg or one piece
Neutral
bonded to groundAPT
via grounding
resistor
Neutral
to ground
equip. (208Y/120V) Rare - Call
V = 277V (480Y/277V) APT ‘4’
V = 120V (208Y/120V) APT ‘2’
V = 220V (380Y/220V) APT ‘7’ (non-USA)
V = 127V (220Y/127V) Call (non-USA)
V = 127V (220Y/127V) APT ‘21’ (non-USA)
Neutral
not, APT
be pulled
into facility
Neutral
usually
pulled(480Y/277V)
into
facility 4-wire
Neutral
bonded to groundV =3-phase
4-wire
Grounded Wye
4-wireVUngrounded
Wye APT ‘4’
V
V may, or may 3-phase
3-phase
Grounded
Wye
R(600Y/347V)
V = 347V
‘8’
277V (480Y/277V)
‘5’
= 277V
APT
V (600Y/347V)
G
G
V
= ‘4’
347V
APT ‘8’
= 277V APT
(480Y/277V)
VV =V
220V
VBecoming
= 220V
(380Y/220V)
APT
‘7’ G(non-USA)
(380Y/220V)
CallAPT
(non-USA)
V
=
220V
(38OY/220V)
Call
(non-USA)
R
popular
system
on
high-tech
Very,
very
Common
Less common than perceived!Neutral NOT bonded to ground
Neutral
bonded
to
ground
Neutral
bonded
to
ground
V = 127V
(220Y/127V)
APT
‘21’
(non-USA)
V
=
347V
(600Y/347V)
‘9’
V
=
347V
(600Y/347V)
APT
V = ‘8’
127V
(220Y/127V)
APT G
‘21’
(non-USA)
V = 347V APT
(600Y/347V)
APT ‘8’
G
V
V
=
120V
(208Y/120V)
Rare
Call
V
=
120V
(120/240V)
APT
‘1’
V
=
120V
APT
‘11’
C
Neutral pulled into facility
Neutral
NOT pulledV into
facility
Neutral may or may
not
be pulled
into facility
C
C
B
V
G
=
220V
(380Y/220V)
APT
‘7’
(non-USA)
V
=
127V
(220Y/127V)
APT ‘21’ (nonSplit-Phase ‘Single-Phase’
G
A
V ‘5’
V CAPT
V B Error/miss-wire?
V = 220V
(380Y/220V)
APT
‘7’ (non-USA)
127V
(220Y/127V)
Call (non-USA)
V
127V
(220Y/127V)
‘21’V(non-USA)
(480Y/277V)
APT
V =G
240V
(240/480V)
Rare - Call
= 240V
APT ‘12’ G V =Rare
GV = 277V
G =Wye
Common
system configuration
system configuration;
Common
system
configuration
at MCC,
A APT ‘9’
3-phase 4-wire
3-phase
4-wire Ungrounded
3-phase 4-wire Grounded
V = 220V (380Y/220V) APT ‘7’ (non(600Y/347V)
V
= 127V
(127/254V)
APT ‘15’ (non-USA)
V(non-USA)
= 277V APT ‘16’
A Grounded Wye
G
GV = 347VWye
V
=
220V
V
=
220V
(380Y/220V)
APT
‘7’
(380Y/220V)
Call
(non-USA)
Sin
V = 120V Neutral
(208Y/120V)
APTto‘2’
Note NEC 285.3(2),
pumping and water treatment
Single-Phase
C
Neutral bonded
to ground Neutral usually pulled
Neutral bonded
NOT bonded
ground
Neutral bonded
to ground.
B
V =Grounded
480V APT ‘17’
Call – almost
always different
Gto ground C C
Impedance
Wye
‘Single-Phase’
Ver
V = 277V Neutral
(480Y/277V)
APT
=C120V (208Y/120V)
Rare - Call
V = 120V Vor
(208Y/120V)
APT
‘2’ Single-Phase
B V Split-Phase
Neutral pulled into facility
Neutral NOT pulled into facility
may or may
not‘4’
be pulled into facilityCBResistive
V = 127V
APT ‘13’ (non-USA)
V
Neutral
bonded
to
ground
via
grounding
resistor
Neutral
bonded
to
ground
Oft
B
A
V
=
347V
(600Y/347V)
APT
‘8’
V
=
277V
(480Y/277V)
APT
‘5’
V
=
277V
(480Y/277V)
APT
‘4’
Verify
where
neutral
and
ground
are!
Often
this
is
used
Common
system
configuration
Rare
system
configuration;
Error/miss-wire?
Common
system
configuration
at
MCC,
A Wye
Single-Phase
into facility.
Very, very Common.
V = 220V
APT3-phase
‘12’
(non-USA)
Resistive
or Impedance
Grounded
Wye
Split-Phase
‘Single-Phase’
A
Verify
where
Neutral
andUngrounded
Ground are!
3-phase
4-wire
Grounded
Wye
4-wire
3-phase
4-wire
Grounded
Neutral
may,
orWye
may not, be
pulled
facility
usually
pulled into
facility
Neu
V = 120V (208Y/120V) APT ‘2’
Note
NEC
285.3(2),
pumping and
water treatment
V Grounded
= 127V
(220Y/127V)
APTSplit-Phase
‘21’
(non-USA)
V Neutral
=one
347V
(600Y/347V)
APT
‘9’
V
= 347V
(600Y/347V)
APT
‘8’ into
A
Resistive
or
Impedance
Wye
‘Single-Phase’
Verify
where
Neutral
and
Ground
are!
Neutral
bonded
to
ground
via
grounding
resistor
Neutral
bonded
to
ground
Often
for
one
leg
or
piece
of
equip.
N
A
N 220V V (380Y/220V)
Neutral bonded
bonded
toBecoming
ground
Neutral
NOTVbonded
to ground
popular
systemNeutral
on
high-tech
Very,
very
Common
V = (120/240V)
277V (480Y/277V)APT
APT ‘1’
‘4’
= 120V (208Y/120V)
Rare
- or
Call
V = 120V (208Y/120V)
APT ‘2’to ground
Les
forAPTone
leg
one
piece
ofintoequipment.
is
bonded
‘7’Neutral
(non-USA)
=piece
127V
Call (non-USA)
V
= 127V
(220Y/127V)
APT
‘21’ (non-USA)
V = 120V
V
bonded
to‘4’
ground
via
grounding
resistor
Neutral
bonded
topulled
ground
Often
forNeutral
onebonded
leg may
or one
of (220Y/127V)
equip.
Neutral
may,
or may
not,
be pulled
into facility
Neutral
usually
pulled
facility
BV =
toor
ground
V = 347V (600Y/347V) APT ‘8’
V = 277V
(480Y/277V)
APT
‘5’
V = 277V Neutral
(480Y/277V)
APT
Neutral
pulled
into
facility
Neutral
NOT
facility
not
be
pulled into
facility
VV=into
(208Y/120V)
CallNeutral
= 120V
(120/240V)
APT
‘1’
V=
VV
=may
220V
=120V
220V
(380Y/220V) Rare
APT -‘7’
(non-USA)
(380Y/220V)
Call
(non-USA)
V
R
Becoming
popular
system
on into
high-tech
Very,
very pulled
Common
Less
common
than
perceived!
may,
or
may
not,
be
pulled
facility
Neutral
usually
into
facility
A
A
Neutral
bonded
to
ground
V = 127V (220Y/127V) APT ‘21’ (non-USA)
V
=
347V
(600Y/347V)
APT
‘9’
V = 347V Neutral
(600Y/347V)
APT
‘8’
AVless
V
= 277V (480Y/277V)
APT commonly
‘5’
V = 240V (240/480V)
Rare - CallN
V=
to
ground.
This
configuration
is
Common system configuration
Rare than
system configuration;
Error/miss-wire?
Common
system
configuration
atused
MCC,
V = 240V
(240/48OV)
Rare
Call
APT
V = 120V
Rare V
- Call
Vvery
= 120V
APT
‘1’
= 120V than
APTperceived!
‘11’V = 127V (127/254V)
popular
system
on high-tech
Very,
Common
V = 220V (380Y/220V) APT ‘7’ (non-USA)
=V127V (220Y/127V)
Call
(non-USA)
V = 127V Becoming
(220Y/127V)
APT (208Y/120V)
‘21’
(non-USA)
LessVcommon
B pumping
V
V =treatment
347V
(600Y/347V)
APT ‘9’
APT ‘15’ (non-USA)
V=
A
G(120/240V)
V
=
120V
(208Y/120V)
APT
‘2’
Note
NEC
285.3(2),
and
water
V
V
V
V = 220V (380Y/220V)
V = 220V V
(380Y/220V)
APT (480Y/277V)
‘7’ (non-USA)
V = 277V
V (non-USA)
=
240V
(240/480V)
V = 240V
= 120V
Rare
-APT
Call‘5’
V =Call
120V
(120/240V)
APT Rare
‘1’ - Call A R
V = 120V
APT APT
‘11’ ‘12’
perceived
(see
“split-phase”).
V=
N - Call
A APT
G(208Y/120V)
V = 127V (127/254V)
APT
‘15’
(non-USA)
V = V277V
(480Y/277V)
‘4’‘9’
V = 120V
(208Y/120V)
Rare
V=
120V
(208Y/120V)
APT
‘2’ (non-USA)
N
=
347V
(600Y/347V)
APT
V
=
127V
(127/254V)
APT
‘15’
V
=
277V
APT
‘16’
V = 277V (480Y/277V) APT ‘5’
V = 240V (240/480V) Rare - Call
V = 240V APT
‘12’
G
V=
V277V
V = 347V (600Y/347V) BAPT ‘8’
V
=
(480Y/277V)
APT
‘5’
V = 277V (480Y/277V) APT ‘4’
A
CB
V
V = 480V
V = 120V
‘11‘ APT ‘15’ (non-USA)
V = 347V
V = 127VAPT
(127/254V)
VV= 277V
APT APT
‘16’ ‘17’ Call – almost always different
V=
A (600Y/347V) APT ‘9’
R
A
V = 127V
(220Y/127V) APT ‘21’ (non-USA)
V = 347V
(600Y/347V)
APT G
‘9’
V = 347V (600Y/347V) APT ‘8’
Single-Phase
V
=
127V
APT
‘13’
(non-USA)
V = 480V APT ‘17’ Call – almost always different
Resistive or Impedance Grounded Wye V = 220V
Split-Phase
‘Single-Phase’
APT ‘7’ A (non-USA)V = 240V
V = 127V
VV
= 127V
APT are!
‘21’ G
(non-USA)
C V = 220V
Verify
where (220Y/127V)
Neutral
and Ground
C (380Y/220V)
APT (220Y/127V)
‘12’
(non-USA)Call
N (non-USA)
APT
‘12’
B
VC= 127V
APT
(non-USA)
V
G C Call
N V
BN
B ‘13’ (380Y/220V)
B
Bof equip.
Neutral bonded to ground via grounding resistor
Neutral bonded to ground
Often
for oneC
leg or one piece
V = 220V
V = 220V
(380Y/220V)
APT
‘7’ (non-USA)
(non-USA)
VImpedance
= 220V APT
‘12’ (non-USA)
A
G
R
Neutral may, or may not, be pulled into facility
Neutral
usually
pulled
into
facility
Resistive
or
Grounded
Wye
Split-Phase ‘Single-Phase’
Neutral
bonded
to
ground
N= 277V APT ‘16’
V
A
N
B
G Very, very
B
Neutral bonded toVground via grounding resistor
Becoming popular
system on high-tech
Less common than perceived!
A G A Neutral bondedVto ground
C Common
G
GV
Hi-Leg Grounded
Delta
V pulled into facility
AAPT
R V = 120V (208Y/120V)
B - almost
Neutral may,
be
Neutral usually pulled into facility
Aor may not,
A APT
BG
Rare - Call
V = 120V (120/240V)
APT ‘1’
V = 48OV
‘17’
always
different
V = 120V
APT
‘11’ Call
A
G
Single-Phase
Becoming popular system on Open
high-tech
Very, very Common
V NeutralAPT
= 277V
(480Y/277V)
‘5’ pulled into
VHi-Leg
= 240VGrounded
(240/480V)
Rare - Call
V
V
GV
Delta
Delta
A = 240V APT ‘12’
A
G
Neutral bondedVVto
ground.
often
V V = 120V
V
A (208Y/120V) Rare3-phase
Resistive
or Impedance
Grounded
Wye
Split-Phase
‘Single-Phase’
- Call 3 where
Vand
= 120V
(120/240V)
Verify
Ground
are! APT ‘1’
V 3-wire
= 127V
APTAPT
‘13’
3-phase
Delta
3-phase 3-wire
BCorner
= 347V (600Y/347V) APT ‘9’
VNeutral
= 127V
(127/254V)
‘15’C(non-USA)
bonded
to groundAPT
or 4-wireNeutralV
VUngrounded
= 277V
‘16’(non-USA)
G
V VDelta
G
V
= 277V
(480Y/277V) APTCould
‘5’
= 240V
Single-Phase
has no reference
to ground
Neutral oftenground
pulled into
facility
ungrounded,
Neutral bonded
via
grounding
resistor
Neutral
ground
Often
for one legcorner
or V
one
piece(240/480V)
of equip. Rare - Call
V = 480V
APTbonded
‘17’ Call to
–Grounded
almost
always
different
Csystem configuration.
VSystem
V
V be
facility. Common
BCommonto
Vreference
= 347V to(600Y/347V)
APTgrounded
‘9’ Verify
= 127V
(127/254V)
APT ‘15’ (non-U
Resistive
or into
Impedance
Grounded
WyeAPT
Split-Phase
‘Single-Phase’
L-L voltages
fixed
but
L-(non-USA)
system configuration
or Hi-leg
where NeutralVand
Ground
are!
V=
220V
APT
‘12’
Systeminto
has
ground
Vby=transformer,
127V
‘13’
(non-USA)
Single-Phase
Neutral may,
or
may
not,
be
pulled
facility
Neutral
usually
pulled
facility
Neutral
bonded
to
ground
C
A
N because
voltages
vary;
become
V = 120/240V APT
‘3’
Very rare,
tend
toone
be rural
Neutral
bonded
to G
ground
viacan
grounding
resistor
Neutral
bonded
to ground
Often
forN
leg or one piece of equip.
B phase
N is grounded
Resistive orAPT
Impedance
Split-Phase
‘Single-Phase’
Verify where
Neutral
and
Ground
are! toAPT
V =Known
220V
(non-USA)
V = 120/240V
‘3’ Grounded Wye
Cperceived!
B
B
Becoming
system
on may,
high-tech
Very,
very‘12’
Common
LessNeutral
common
unstable.
V popular
= 240/480V
Call’
Various
solutions,
Callthan
for
V =usually
240V APT
‘61’into facility
Neutral
orfor
may
not,
pulled
intooffacility
Neutral
pulled
bonded
toinfo
ground
Neutral bonded to ground via grounding resistor
Neutral bonded to ground
Often
one
leg be
or one
piece
equip.
R
C
A
V
=
240V
APT
‘6’
V = 120V
(208Y/120V)
-popular
Call bonded
= 120V (120/240V)
APT
‘1’
Vvery
= 480V
APT ‘51’
120V
APT than
‘11’ perceived!
Becoming
system
on
high-tech V 3-wire
Very,
Common
common
Neutral may, or
may APT
not, be pulled into facility
Neutral usually
pulled into
facility
to3-phase
ground
N Rare Neutral
V = 240/48OV
Call
Ungrounded
Delta C VV == Less
B APT
V = 480V
APT
‘5’
B
B - Call
B ‘91’
C
V = 600V
APT
(208Y/120V)
Rare
V = 120V
(120/240V)
APT ‘1’
Becoming popular system on high-tech
Very, veryVCommon
V240V
= 120V
APT‘12’
‘11’
Less
common
than
perceived!
= 277V (480Y/277V)V =APT
‘5’
V = 240V C(240/480V)
Rare
- Call
V120V
G
G G
V APT
= 600V
APT
C
A V(480Y/277V)
Note NEC
285.3(2) Rare - Call
AGAPT
V = 120V (208Y/120V) Rare - Call
V = 120V V(120/240V)
‘1’
‘11’
V =APT
277V
APT
‘5’‘9’ has
V = 240V
(240/480V)
V277V
= 240VAPT
APT‘16’
‘12’
Bfixed by
A285.3(2)
= 347V AAPT
(600Y/347V)
‘9’= 120V Note
V
=
127V
(127/254V)
‘15’
(non-USA)
V
=
System
NO
reference
to
ground.
L-L
voltages
N
NEC
Occasionally
seen
at
industrial
G
B
C
B‘12’
B
C
C
V = 277V (480Y/277V) APT ‘5’
V = 240V (240/480V) Rare - Call
= 240V APT
V = 347V V(600Y/347V)
APT ‘9’
V = 127V
(127/254V)
APT ‘15’ (non-USA)
V
=
277V
APT
‘16’
Hi-Leg
Grounded
Delta
A
V
G
system configuration at older
V = V480V
APT
‘17’ Call––almost
almost
always different
G
facilities, normally not used on new
V
V
V = 347V (600Y/347V) APT ‘9’
V = 127V
(127/254V)
APT C
‘15’G
(non-USA)
V =V277V Common
APT ‘16’G
= 480V
APT ‘17’ Call
always different
3-phaseV3-wire
Ungrounded
Delta
3-phase
3-wire Corner
transformer,
but
L-G
voltages
cantovary.
bonded
ground
facilities,
normally
not different
used
onNeutral
B construction
V = 480V industrial
APT ‘17’
Call – almost
always
V
= V127V
‘13’
(non-USA)
127V
APT
‘13’ (non-USA)
3/16/09
V APT
V
Single-Phase
SystemRev
hasDate:
no =
reference
to
ground
Neutral
Grounded Delta
Hi-Leg Grounded Delta V = 127V new
Open
Delta
APT
‘13’ (non-USA)
Goften pulled into facility
Gconstruction
V
=
220V
APT
‘12’
(non-USA)
V
=
220V
APT
‘12’
(non-USA)
Voltage
Diagrams
RevC
G
This
configuration
is
known
to
become
unstable.
L-L voltages
by
transformer,
butare!
LCommon
configuration
Resistive
orbonded
Impedance
Wye
Split-Phase
‘Single-Phase’
Verify
where fixed
Neutral
and Ground
System has reference to g
V = 220V 3-phase
APT ‘12’ (non-USA)
3-wire
Ungrounded
Delta system
3-phase
3-wire Corner
Neutral
to groundGrounded
3-phase
3 or 4-wire
3-phase 3-wire Corner Grounded Delta
G voltages
canleg
vary;
Known
to become
Vground
= 120/240V
APT ‘3’ Delta
because
B
phase
is groun
Neutral
bonded
to
ground
via
grounding
resistor
Neutral
bonded
to
Often
for
one
or
one
piece
of
equip.
System
has
no
reference
to
ground
Neutral
often
pulled
into
facility
Could
be
ungrounded,
corner
Grounded
Hi-Leg Grounded Delta
Open Delta
V = 240V
‘6’
B voltages
unstable.
V
= L240/480V
Call’ has reference toNeutral
V = 240V APT ‘61’
Neutral
may,
orsystem
may
not,
be pulled into
facility
Neutral
usually
pulled
into
facility
L-L
by APT
transformer,
but
Common
or Hi-leg
bonded
togrounded
ground
Bconfiguration
C B to ground because
A
System
3-phase
3-wire fixed
Ungrounded
Delta
3-phase
3-wire Corner ground
Neutral
bonded
to
ground
3 or 4-wire
System has reference
V = 240V
APT3-phase
‘6’ Very
A
AV = 480V APT ‘51’
N
A
A
G
voltages
can
vary;
Known
to
become
V
=
120/240V
APT
‘3’
rare,
tend
to
be
rural
B
Becoming
popular
system
on
high-tech
Very,
very
Common
A
C
Less
common
than
perceived!
B
because
B
phase
is
grounded
B
C
C
C
A
A
System hasVno=
reference
to
Neutral often pulled into facility
be ungrounded, corner VA= 600V APT ‘91’
Aground
48OV
APT
‘5’
Grounded Delta
= 480V APTCould
‘5’ Various
NVVA
unstable.
V = 240/480V
Call’ Rare - CallL-L voltages
Call for info
C
B
=has
240V
APT ‘61’
VVtransformer,
VCommon
= 120V
(208Y/120V)
= 120V
(120/240V)
APTV‘1’
= 120V APT
‘11’ B
V
B phase is grounded.
but Lsystem
grounded
or solutions,
Hi-leg
V
Vto ground
V
V fixed by
V
V configuration
System
reference
V = 600V APT
‘9’
Note NEC 285.3(2)
V = 240V
APT
‘6’= 240V
480VV APT ‘51’
VV== 277V
(480Y/277V)
APT ‘5’ V
V
(240/480V)
RareV -=Call
= 240V
APT
‘12’
V =vary;
600V
APT
‘9’
G voltages
can
Known
to become
120/240V
APT ‘3’
Very
rare, tendVto be rural
V480V
NEC 285.3(2)
because
B phase is groundedVNote
Occasionally seen at indus
G
G
V
=
APT
‘5’
V‘15’
= 600V
APT ‘91’
V = 240V APT ‘61‘
G
VV== 347V
(600Y/347V)
APT ‘9’
V = 127V (127/254V) VAPT
(non-USA)
VCommon
= 277V system
APT
‘16’
unstable.
240/480V
Call’
Various
solutions,
configuration
at Call
olderfor info facilities, normally
G
=
240V
APT
‘61’
G
not
used
V = 600V
APT
‘9’ 285.3(2)
G
Note NEC 285.3(2)
Note
NEC
Vindustrial
= 480V facilities,
APT ‘17’
Call – not
almost
different
normally
usedalways
on
V = 240V
construction
= 480V
APT ‘51’
OpenVDelta
Note APT
NEC ‘6’
285.3(2)
V = 48OV
APTHi-Leg
‘51’ Grounded Delta
Occasionally
seen at industrial
VDelta
= 127V
APT ‘13’ (non-USA)
new
construction
Hi-Leg
Grounded
V = 480V
APT
‘5’
3-phase 3-wire Ungrounded Delta
3-phase
3-wire
Corner
V
=
600V
APT
‘91’
Neutral bonded toAground
3-phase
3
or
4-wire
C
Common
system
configuration
at older
facilities,
normally
not
used
new APT3-phase
Common
systemCconfiguration
atNeutral
older
industrial
facilities.
C
A
3-wire Ungrounded Delta
3-phase 3bonded
to ground
V =on
220V
‘12’ (non-USA)
Bfacilities,
B
VC= 600V
APT
‘9’
System has C
no reference to ground
Could
be ungrounded,
corner
N Delta
NEC
285.3(2)
Grounded
V = 600V APTNeutral
‘91‘Noften pulled into facilityB
industrial
normallyBnot
used
on Note
B
CNeutral
construction
B into facility
C has no reference
C Grounded
System
often pulled
Rev Date: 3/16/09 to ground
Note has
NEC
285.3(2)
L-L voltages fixed by transformer, but LCommon system configuration
grounded
ornew
Hi-leg
Occasionally
seen
at industrial
System
to ground
newreference
construction
Normally,
this
is
not
used
on
construction.
C
A
L-L
voltages
fixed
by
transformer,
but
LCommon
system
configuration
System has
G voltages can vary; Known
become
V = 120/240V APT ‘3’
tend normally
to be ruralnot used on new
Common
system
configuration at older Very rare,
Note NEC 285.3(2)
Voltage Diagrams
RevC
because
B phase
is grounded
facilities,
G to B
N
G
to become
V = 120/240V
B Known
G = 240/480V Call’
C construction
because
Bp
B normally notGused onVarious
B info
CG voltages can vary;
C
G APT ‘3’
unstable.
V
solutions, Call for
facilities,
VG
=industrial
240V APT
‘61’
unstable.
V = 240/480VACall’
A
A
V = 240V A
Rev
Date:
3/16/09
Occasionally
seen atDelta
industrial facilities. V = 240V APT ‘6’
Hi-Leg Grounded
Open Delta
V =new
480V
APT
‘51’
construction
V = 240V APT ‘6’
Open
Delta
V = 480V A
Hi-Leg
Grounded
Open
Delta
3-phase 3-wire VUngrounded
3-phase 3-wire
Corner
Neutral bonded to ground
3-phase 3 or 4-wire
= 480V APTDelta
‘5’
V
Voltage
Diagrams
RevC
V = 600VVDelta
APT ‘91’
VV
= 480V APT ‘5’
V G
V = 600V A
System
has no reference
to ground
3-wire
3-phase 3-wire Corner
Neutral
oftenis
pulled
facilityon new
Could be ungrounded,
corner Ungrounded Delta
Normally,
this
notintoused
construction.
ground
3-phase 3 or 4-wire
Delta bonded
G
V = 600V
APT ‘9’
Note to
NEC
285.3(2)
GGroundedNeutral
V = 600V APT ‘9’
3-phase
33-phase
or 4-wire.
Note NEC 2
Common system configuration
V = 120/240V APT ‘3’
V = 240/480V Call’
L-L voltages fixed Note
by transformer,
but Lgrounded or
Hi-leg has no reference to ground
System has Neutral
reference
toOccasionally
ground
System
often
pulled into facility
Could be ungrounded, corner
Grounded Delta
NEC 285.3(2)
seen
at industrial
Note NEC 285.3(2)
Occasionally
G voltages can vary; Known to become
Very rare, tend
to be ruralfixed by transformer, but Lbecause
phase
is grounded
L-L
Common
system
configuration
groundedDelta
or Hi-leg
System has reference to ground
CommonHi-Leg
system configuration
atBolder
facilities,
normallyVarious
not used
onvoltages
new
Grounded
Open
Common system configuration
at older
unstable.
solutions,
Call for
V = 240V Delta
APT
‘61’
G
voltages
caninfo
vary; Known to become
V
=
120/240V
APT
‘3’
Very rare, tend to be rural facilities, nor
because B phase is grounded
facilities,bonded
normallyto
notground
used on
construction
industrial facilities,3-phase
normally not
used
on
construction
V = 240V APT ‘6’industrialNeutral
3-phase
3-wire
Ungrounded
Delta
3-phase
3-wire
Corner
3
or
4-wire
V = 480V
APT
‘51’
unstable.
V = 240/480V Call’
Various solutions, Call for info
Rev Date: 3/16/09
V = 240V APT ‘61’
new construction
V = 480V APT ‘5’new construction
V = 600Vinto
APT
‘91’
System has no reference
to ground
Neutral
facility
Could be ungrounded, corner
Grounded
Delta
V = 240V APT
‘6’Voltage Diagrams
C often pulled
A
APT ‘51’
RevCV = 480V
V = 600V APT ‘9’
Note NEC
N 285.3(2)
V =by
480V
APT
fixed
transformer,
Common system
configuration
grounded orCHi-leg
= 600V
APT
C ‘5’ but LB
B System Vhas
C ‘91’
reference
to ground B
Note NEC 285.3(2)
Occasionally
seen at industrial L-L voltages
V = 600V
APT to
‘9’ become
NEC 285.3(2)
Common system configuration
older
G voltages can vary;
Known
V =at120/240V
APT ‘3’
Very rare, tend to be rural
facilities,
normally not used on new
becauseNote
B phase
is grounded
Note NEC 285.3(2)
Occasionally seen at industrial
industrial facilities, normallyV
not=used
on
construction
unstable.Rev Date:Common
240/480V
Call’
Various solutions, Call for info
V = 240V
APT ‘61’
3/16/09 system configuration
new construction
facilities, normally not used on new
G at older
G
Could be ungrounded, corner grounded or Hi-leg.
Very rare, tend to be rural. Various solutions.
Call APT for information.
G
Hi-Leg Grounded Delta
Neutral bonded to ground
Neutral often pulled into facility
Common system configuration
V = 120/240V APT ‘3’
V = 240/480V Call’
“Protecting the electronic world from surges”
V = 240V
APTDiagrams
‘6’
Voltage
APT ‘51’
industrial RevC
facilities, normally not usedVon= 480V
th construction
Rev Date: 3/16/09
V = 480V APT ‘5’
new construction
V = 600V APT ‘91’
Open Delta
Voltage Diagrams RevC
V = 600V
APTUngrounded
‘9’
Note
NEC Corner
285.3(2)
3-phase
3-wire
Delta
3-phase
3-wire
3-phase 3 or 4-wire
Note has
NEC
Occasionally
System
no285.3(2)
reference to ground
Grounded
Delta seen at industrial Could be ungrounded, corner
system
configuration
L-LCommon
voltages fixed
by transformer,
butatL-older Systemfacilities,
normally
not used on new
grounded or Hi-leg
has reference
to ground
industrialcan
facilities,
normally
not used onbecause
G voltages
vary; Known
to become
Very rare, tend to be rural
construction
B phase is grounded
Rev Date:
3/16/09
unstable.
Various solutions,
Call for
info
new construction
V = 240V APT ‘61’
14550 58 Street North, Clearwater, Florida 33760
(727) 535-6339 • (800) 237-4567 • Fax (727) 539-8955
www.aptsurge.com • info@aptsurge.com
V = 240V APT ‘6’
V = 480V APT ‘5’
V = 600V APT ‘9’
Note NEC 285.3(2)
V = 480V APT ‘51’
V = 600V APT ‘91’
Note NEC 285.3(2)
Occasionally seen at industrial
Voltage Diagrams RevC