UL 2703
Mounting systems, clamping/retention devices, and grounding/bonding hardware.
What UL 2703 covers
How a panel is mechanically held and electrically bonded — rails, mid/end clamps, retention devices, and ground lugs. UL 3700 references UL 2703 for the mounting portion of a kit.
Why it matters for balcony solar
Railing mounting is the part most likely to be improvised, and the part a wind load actually tests. UL 2703 is the standard for doing it with rated hardware instead of generic brackets.
The common mix-up
Racking looks like the low-stakes part, so it's where people substitute generic hardware. It has its own safety standard for a reason — grounding and wind load both run through it.
UL 2703 is one of several UL standards behind a plug-in system. See how they fit together →
What to look for when buying
Buy clamps and rails rated for your railing and panel, not improvised brackets. UL 2703 is the mark.