120/240 V 1? panel fed from 120/208V 3? 4W

[srisser]

I am reviewing a set of plans with a 120/208V 3? 4W electrical service to an 120/208V 3? 4W MDP. Fed from the MDP is a 120/240V 1? 3W sub panel. There is no transformer between the two panels. The feeders consist of two conductors (I am assuming one hot, one neutral) and an equipment ground. All of the loads server by the 120/240V panel are 120V loads only. I have the following questions...1. Shouldn't the 120/240 panel be a 120/208V panel board as the panelboard is required to be marked by the manufacturer per NEC 408.58? 2. When calculating the feeder and service load, shouldn't 120V be used per NEC 220.5? The designer used 208V to calculate his loads. If you have 120V loads from the single phase panel, you only have 120V single phase loads...correct?

The loads appear to be balanced across the 3? panel as there are some other 120 and 208 loads on other phases that the 120/240 V is not connected to.

 

[Smart $]

1. I agree, but others say it is okay.

2. To achieve the highest degree of accuracy, you should calculate 120V and 208V loads separately, for the single phase panel. Here is an example I did for another post awhile back...

Separating 120V and 208V loads on a 3? panel is not necessary, provided they are fairly well balanced.

 

[don_resqcapt19]

Is there such a thing as a single phase panel marked for 120/208? I have never seen one.

 

[jim dungar]

Panels are usually marked for a maximum voltage (both line-line and line-ground), based on the correct number of 'wires'.

A 120/240V 3W panel can be used on a 120/208V 3W circuit.

A 120/240V 3W panel cannot be used on a 120V 2W circuit.

 

[LarryFine]

The feeders consist of two conductors (I am assuming one hot, one neutral) and an equipment ground.

It should contain two line conductors, along with a neutral and EGC. Otherwise, it's only 120v 1ph.

And, as mentioned above, a 120/240v panel is fine on 120/2081ph.