Showing voltage over disconnect breaker when off?

good question, lets go socratic method.

if you reply, tell us which load center is in use, and i can provide more detail.

"I have the disconnect breaker wired on the top going to the positive inverter connection and on the bottom to the positive battery bank terminal and the positive pv output breaker"

Q: so, where is the bottom of the breaker connected to?
A: "and on the bottom to the positive battery bank terminal"

Q: so . . . if the bottom of the inverter disconnect circuit breaker is connected to the positive terminal on the battery bank can it ever be off?

A: no, because it is opening the circuit between the battery terminal and the inverter, not the battery and the box, or more specifically the bottom of the breaker.

Q: does the same hold true for the negative busbar?

A: yep, the busbars (and bottom of inverter disconnect either holding one or acting like one) are extensions of the battery bank terminals.  they are always live, as you cant turn the batteries off.

because the busbars in a DC load center are always energized by the battery bank, it is very important that safety gear (appropriate ppe) and precautions are used when operating inside one.  the disconnects (pv, controller, inverter, loads) all
disconnect each other from sources.  with pv and batteries, it is important to remember that opening a disconnect may stop current flow after that disconnect, but there is no stopping the potential for voltage (and current in the event of a short) from a source before that disconnect. 

you would expect voltage across the postive and negative busbars in a dc load center.  they are merely an extension of the terminals inside a box, to facilitate connecting all those disconnects and branch circuits.  should you try to measure current (WHICH YOU SHOULD NOT) you may have an explosion as you would short the battery bank.

hope that helps,

james
altE staff

James, thanks very much for your quick response. Somehow I was expecting an open but I"m glad to know it's wired OK..I just somehow expected the breaker to create open the circuit.  I'll disconnect the terminal to one battery post before I do any more work inside the box.  I guess I'll have to re-read what the DC quick disconnect actually disconnects.

TO John:  I guess I was not clear in my post.  I was not taking a voltage from the bottom of the breaker to a the battery terminal I was taking the voltage from the bottom of the DC disconnect breaker to the negative post on the **Inside Negative Post*** in the DC box...I guess it's considered the negative bus bar.   I don't think the leads on my multimeter would reach from the inside of the DC positive breaker to the battery bank

Thanks again everyone!!!