There are many different 3Ø systems so it might be helpful to label this according to the system it is actually representing. Based on the color scheme depicted of Black/Red/Blue/White this would be a 208Y/120 volt system.
Also if you’re going to say that the three phase conductors are 120 volts then you shouldn’t say that There also may also be a neutral (grounded) conductor present. Without the neutral conductor there would not be any 120 volt circuits so it must be present. Also a Wye service must have a neutral conductor so the mention of an optional neutral is incorrect.
A bond bushing may or not be required. It is voltage dependent along with whether this is a service or a feeder to a distribution panel and knockout type.
The incoming conductors are not always service conductors. They could be feeder conductors.
The ground does not always go to a grounding electrode. Nor is a bond screw always required. The bonding jumper may not be required also.
The panel may or may not have or need a main breaker.
The neutral should be identified at its termination.
It appears that the graphic is depicting a 3Ø service. Maybe it should clearly indicate that it is actually a 3Ø service to avoid confusion.
Service or distribution panel would help.
- The label Ground Busbar should say Neutral Busbar as they are connected together with the tie bar at the bottom.
- Since this is a service there should be a green screw or strap serving as the main bonding jumper (MBJ).
- One minor thing is that the SPD should have the neutral landed on the neutral bus on the left as the conductors for SPD’s should be a short as practicable.
- Also this is a 3Ø system so there should be a 3-pole breaker depicted for the SPD power not a 2-pole.
- The 120V/208V is an improvement. The NEC and IEEE terminology for defining this system is 208Y/120 volts.
The SPD is not “wrong”, but the way it’s dawn encourages a common mistake which is to double tap the breaker. The SPD needs a dedicated non-AFCI non-GFCI breaker, or a breaker listed for two taps. Or a panel mounted breaker.
Why a two wire SPD, when there are THREE phases?
The 3-pole breaker for the SPD is good but the SPD is missing the third black conductor from the circuit breaker. Also the previous graphic had the green EGC from the SPD that is now missing and is required for the SPD so it needs to be put back. It can connect to the neutral bus on the left.
Hit refresh: 3-Phase Panel (208Y - 120V) - Inspection Gallery - InterNACHI®
Better?
Better!
First Issue:
But not aligned with @rmeier2 here. The SPD should only have a white wire, no green at all.
Check a typical part number like Square D SDSA2040 to see the connections.
Note the SDSA2040 labels the wires A B and C.
Second issue:
Since this is an awareness graphic, not a serious attempt to teach three phase, I recommend labeling the phases A B and C. Then label the three bus bars A B and C. The goal would for inspectors seeing an ABC/3P/208Y panel to quickly identify it, and get out of Dodge City as quickly as possible. There’s too much to know to summarize. An inspector seeing a 120V outlet on “Phase B” should think back to this graphic, and know where that came from.
Third issue:
Ad drawn that’s a dedicated breaker, and the word dedicated would not be inappropriate.
Fourth issue:
The warning against doing 3 phase inspections could be stronger. Is a HI ready to verify phase rotation, for example?
Typical three phase SPD, model SDSA2040 from Square D. Note
the labeled A, B, C and neutral wires, and plastic (non-conductive) case:
Eaton makes 3 phase SPD’s with an EGC.
I looked up the part number. The probable reason that has no EGC is because it’s a Type 1 designed to go ahead of the servcie disconnect where there would not be an EGC. In Nick’s graphic the SPD is a not a Type 1 but a Type 2 which would have an EGC.
If so then maybe the fix for the graphic is to label it as a “Type 2 SPD”.
I see the Type 2 part number SSP02XDSE20A is listed as 4 wire, but appears to have 5 wires (ABC, N, G) and is listed as having separate G ratings:
700 V L-N
700 V L - G
600 V L - L
1000 V N - G
Though given that N and G are bonded at this point, would it make a difference if a Type 1 were used?
According to the NEC there are specific uses for each type. Type 1 can be installed as a Type 2.
Surge-Protective Device (SPD).
A protective device for limiting transient voltages by diverting or limiting surge current; it also prevents continued flow of follow current while remaining capable of repeating these functions and is designated as follows:
Type 1: Permanently connected SPDs intended for installation between the secondary of the service transformer and the line side of the service disconnect overcurrent device.
Type 2: Permanently connected SPDs intended for installation on the load side of the service disconnect overcurrent device, including SPDs located at the branch panel.242.12 Type 1 SPDs.
Type 1 SPDs shall be installed in accordance with 242.12(A) and (B).
242.12(A) Installation.
Type 1 SPDs shall be permitted to be connected in accordance with one of the following:
(1) To the supply side of the service disconnect as permitted in 230.82
(2) As specified in 242.14
242.12(B) At the Service.
When installed at services, Type 1 SPDs shall be connected to one of the following:
(1) Grounded service conductor
(2) Grounding electrode conductor
(3) Grounding electrode for the service
(4)Equipment grounding terminal in the service equipment
242.14 Type 2 SPDs.
Type 2 SPDs shall be installed in accordance with 242.14(A) through (C).
242.14(A) Service-Supplied Building or Structure.
Type 2 SPDs shall be connected anywhere on the load side of a service disconnect overcurrent device required in 230.91 unless installed in accordance with 230.82(8).
242.14(B) Feeder-Supplied Building or Structure.
Type 2 SPDs shall be connected at the building or structure anywhere on the load side of the first overcurrent device at the building or structure.
242.14(C) Separately Derived System.
The SPD shall be connected on the load side of the first overcurrent device in a separately derived system.