Square D panel question

Status
Not open for further replies.
jim dungar said:
Measure the nominal voltage Line-Neutral.
120V is good to go.
208V means you are on the wild/high leg.

Straight 2-wire 240V loads can be connected to the wild leg
Click to expand...


A circuit breaker w/ a 120/240V slash rating cannot be used on the high leg a 240V 2-pole must be used, cost & availability could be a issue.
 
The utility metering will measure accurately even if loads are connected High leg - neutral.

High leg - Neutral loads are avoided for several reasons (i.e. neutral sizing and 1-pole breaker ratings) but metering is not one of them.

High-leg delta systems have been in use since the early days of rural electrification (the 30's?), so I imagine that is when POCO's figured out how to meter them.
 
I knew it was a tale.
But I thought I had seen a meter that did not seem to measure the high leg years ago,
There is not much delta systems in my area. Have not worked on one in 10 years.
 
Last edited:
Roach said:
...I will be sure to get it marked clearly to define which is 120V and which are 240...
Click to expand...
Please do not mark the B-phase high leg as 240V. It should actually be closer to 208V to ground. The correct system terminology is 240/120V 3? 4W ("W" meaning number of wires not counting any grounding conductor). Some will, for the sake of the untrained, append that with Delta High Leg or something similar. Even marking the B phase as "240V only" isn't enough for an unqualified, weekend warrior (want-to-be)—refer to norcal's post.

FWIW, current code requires the B phase (high leg) to be marked orange by any of a few compliant means. There has been some debate as to colors of A and C, since none are mandated by the NEC.
 
Last edited:
Smart $ said:
Please do not mark the B-phase high leg as 240V. It should actually be closer to 208V to ground.
Click to expand...
I believe they use "240v" because only line-to-line loads, either 1ph or 3ph, can use the high leg, and they would indeed receive 240v.

Any load that uses a neutral connecton will be wired as if from a 120/240v 1ph supply.
 
LarryFine said:
I believe they use "240v" because only line-to-line loads, either 1ph or 3ph, can use the high leg, and they would indeed receive 240v.

Any load that uses a neutral connecton will be wired as if from a 120/240v 1ph supply.
Click to expand...
I understand that, but even if so noted as 240V use only, its still a bit short from explaining the breaker must be rated for a full 240, and not just 120/240.
 
Smart $ said:
I understand that, but even if so noted as 240V use only, its still a bit short from explaining the breaker must be rated for a full 240, and not just 120/240.
Click to expand...
There are many other NEC requirements that are not spelled out on equipment labels. That's why we exist.
 
Status
Not open for further replies.
Top