Question

Question: Hello,I have worked mostly with 120VAC panels, and this is the first time that I will be working with 120 and 208 VAC in the same panel.The devices that I need to work with are 5 chargers, a controller and 3 workstations.The chargers are going to be fed with 208VAC, they have a max current of 15A (L-L) each.The controller is going to be fed with 120VAC, with a max current of 8A (L-N).The workstations are going to be fed with 120VAC, with a max current of 4A (L-N) each.As for the chargers, that are going to be fed with 208VAC L-L, the current has to be taken into account for each line ? Below I left the panel distribution:ABCWS14WS24WS34CONTROLLER8CHARGER 11515CHARGER 21515CHARGER 31515CHARGER 41515CHARGER 51515TOTAL576449

Answer 1

Okay, this is a common scenario, and it's good you're being cautious. Let's break down how to size your panel and breakers for this configuration.

Understanding 208V and 120V in a Panel 208V (Line-to-Line)

This is achieved by connecting to two different hot legs (phases) of a 3-phase system. In your panel layout, this is indicated by the chargers being connected to two lines and no neutral.

120V (Line-to-Neutral)

This is achieved by connecting one hot leg (phase) to the neutral conductor. In your panel layout, this is indicated by the controller and workstations.

Panel Calculations and Distribution

Your panel is three phase so it is possible to distribute the load evenly to avoid issues, which in your current layout you are not doing.Here's a breakdown of the current draw on each phase, and recommendations for balancing the load: Phase A

Workstation 1: 4A Charger 1: 15A (this 15A draw affects both Phase A and Phase B) Charger 2: 15A (this 15A draw affects both Phase A and Phase C)

Total Phase A: 4A (Workstation) + 15A (Charger 1) + 15A (Charger 2) = 34A Phase B

Workstation 2: 4A Charger 1: 15A (this 15A draw affects both Phase A and Phase B) Charger 3: 15A (this 15A draw affects both Phase B and Phase C)

Total Phase B: 4A (Workstation) + 15A (Charger 1) + 15A (Charger 3) = 34A Phase C

Workstation 3: 4A Controller: 8A Charger 2: 15A (this 15A draw affects both Phase A and Phase C) Charger 3: 15A (this 15A draw affects both Phase B and Phase C) Charger 4: 15A (this 15A draw affects both Phase C and Phase A) Charger 5: 15A (this 15A draw affects both Phase C and Phase B)

Total Phase C: 4A (Workstation) + 8A (Controller) + 15A (Charger 2) + 15A (Charger 3) + 15A (Charger 4) + 15A (Charger 5) = 72AKey Considerations

Load Balancing

The biggest issue is the imbalance. Phase C is significantly overloaded compared to Phases A and B. This can lead to voltage imbalances and potentially damage equipment.

Breaker Sizing

Breakers should be sized based on the load they are protecting and the wire gauge used for the circuit. Your 15A chargers likely need a 20A breaker and appropriate wire gauge to account for continuous operation (125% rule, see below).

Continuous Loads

Chargers are likely considered "continuous loads" (operating for 3 hours or more at a time). The NEC (National Electrical Code) requires you to size breakers and conductors for continuous loads at 125% of the continuous load current. 15A 1.25 = 18.75A. This means a minimum 20A breaker and wire gauge sized for at least 20A (typically 12 AWG copper).

Panel Size

Your panel needs to be large enough to accommodate all the breakers, with some spare capacity for future expansion. Your current calculated load (72A) is a significant amount. I recommend a panel with at least 100A capacity, and preferably larger (125A or 150A) to allow for growth.

Neutral Conductor

The neutral conductor must be sized appropriately to handle the unbalanced load from the 120V circuits.

Grounding

Ensure proper grounding of the panel and all equipment.

Revised Panel Distribution (Example for better load balancing)

This is just an example. You may need to adjust based on available breaker slots and physical layout considerations. This is an attempt to balance the load, it may require adjustment with a multimeter once installed to balance the load.

A	B	CWS1	4	-	-WS2	-	4	-WS3	-	-	4Controller	-	8	-Charger 1	15	15	-Charger 2	15	-	15Charger 3	-	15	15Charger 4	15	-	15Charger 5	-	15	15Total	49	57	64

Phase A

Workstation 1, Charger 1, Charger 2, Charger 4

Phase B

Workstation 2, Controller, Charger 1, Charger 3, Charger 5

Phase C

Workstation 3, Charger 2, Charger 3, Charger 4, Charger 5

Phase Loads (with proposed redistribution)

Phase A

4A + 15A + 15A + 15A = 49A

Phase B

4A + 8A + 15A + 15A + 15A = 57A

Phase C

4A + 15A + 15A + 15A + 15A = 64A

Breaker Sizing (Example)

Workstations

20A breaker (for each), 12 AWG wire (minimum) - allows for some plug load other than just the workstation to be plugged in. 15A breaker and 14 AWG would also work, but leaves less flexibility.

Controller

15A breaker, 14 AWG wire (or as specified by the controller's documentation).

Chargers

20A breaker (two-pole, since it's 208V), 12 AWG wire (minimum).

Crucial Steps to Take

Consult a Qualified Electrician

This is essential. Working with 208V and 120V in a 3-phase panel requires expertise. An electrician can perform the load calculations accurately, ensure proper load balancing, select the correct panel size and components, and ensure all wiring meets local codes.2.

Accurate Load Calculations

Get the actual current draw of each device. Nameplate ratings are a maximum, not necessarily what the device draws under normal operation. You can use a clamp meter to measure the current.3.

Local Codes and Permits

Comply with all local electrical codes and obtain necessary permits before starting any work.

In summary, while it's possible to run both 120V and 208V devices from the same panel, you MUST ensure proper load balancing, correct breaker sizing, appropriate wire gauge, and compliance with all electrical codes. Get a qualified electrician involved to ensure the safety and reliability of your system. Flag for review

Answer 2

Okay, this is a common scenario, and it's good you're being cautious. Let's break down how to size your panel and breakers for this configuration.

Understanding 208V and 120V in a Panel 208V (Line-to-Line)

This is achieved by connecting to two different hot legs (phases) of a 3-phase system. In your panel layout, this is indicated by the chargers being connected to two lines and no neutral.

120V (Line-to-Neutral)

This is achieved by connecting one hot leg (phase) to the neutral conductor. In your panel layout, this is indicated by the controller and workstations.

Panel Calculations and Distribution

Your panel is three phase so it is possible to distribute the load evenly to avoid issues, which in your current layout you are not doing.Here's a breakdown of the current draw on each phase, and recommendations for balancing the load: Phase A

Workstation 1: 4A Charger 1: 15A (this 15A draw affects both Phase A and Phase B) Charger 2: 15A (this 15A draw affects both Phase A and Phase C)

Total Phase A: 4A (Workstation) + 15A (Charger 1) + 15A (Charger 2) = 34A Phase B

Workstation 2: 4A Charger 1: 15A (this 15A draw affects both Phase A and Phase B) Charger 3: 15A (this 15A draw affects both Phase B and Phase C)

Total Phase B: 4A (Workstation) + 15A (Charger 1) + 15A (Charger 3) = 34A Phase C

Workstation 3: 4A Controller: 8A Charger 2: 15A (this 15A draw affects both Phase A and Phase C) Charger 3: 15A (this 15A draw affects both Phase B and Phase C) Charger 4: 15A (this 15A draw affects both Phase C and Phase A) Charger 5: 15A (this 15A draw affects both Phase C and Phase B)

Total Phase C: 4A (Workstation) + 8A (Controller) + 15A (Charger 2) + 15A (Charger 3) + 15A (Charger 4) + 15A (Charger 5) = 72AKey Considerations

Load Balancing

The biggest issue is the imbalance. Phase C is significantly overloaded compared to Phases A and B. This can lead to voltage imbalances and potentially damage equipment.

Breaker Sizing

Breakers should be sized based on the load they are protecting and the wire gauge used for the circuit. Your 15A chargers likely need a 20A breaker and appropriate wire gauge to account for continuous operation (125% rule, see below).

Continuous Loads

Chargers are likely considered "continuous loads" (operating for 3 hours or more at a time). The NEC (National Electrical Code) requires you to size breakers and conductors for continuous loads at 125% of the continuous load current. 15A 1.25 = 18.75A. This means a minimum 20A breaker and wire gauge sized for at least 20A (typically 12 AWG copper).

Panel Size

Your panel needs to be large enough to accommodate all the breakers, with some spare capacity for future expansion. Your current calculated load (72A) is a significant amount. I recommend a panel with at least 100A capacity, and preferably larger (125A or 150A) to allow for growth.

Neutral Conductor

The neutral conductor must be sized appropriately to handle the unbalanced load from the 120V circuits.

Grounding

Ensure proper grounding of the panel and all equipment.

Revised Panel Distribution (Example for better load balancing)

This is just an example. You may need to adjust based on available breaker slots and physical layout considerations. This is an attempt to balance the load, it may require adjustment with a multimeter once installed to balance the load.

Topic: Panel Size with 120/208