For panel buyers
SCCR for industrial control panels, explained
A panel's short-circuit current rating (SCCR) tells you how much fault current it can safely be connected to. Here is what the rating means, why a panel has to carry it, what sets it, and how our shop handles it.
What SCCR is
The short-circuit current rating is the highest prospective fault current, at a stated voltage, that a panel can be connected to without damage beyond what the standard allows. It is marked in amperes, often in kA (thousands of amperes), together with the voltage it applies to.
SCCR is not the same as the interrupting rating of a fuse or circuit breaker. An interrupting rating says how much fault current a protective device can safely interrupt; the SCCR applies to the whole assembly, including every component in its power circuit.
Why a panel has to be marked with it
The National Electrical Code requires an industrial control panel to be marked with its short-circuit current rating, except a panel that contains only control-circuit components (section 409.110). It also says a panel may not be installed where the available fault current exceeds that marked rating (section 409.22).
That is why the available fault current matters when you order a panel. A rating that turns out to be too low for the installation usually means changing components after the build, so it is better settled at the quote.
What sets a panel's rating
UL 508A, in its Supplement SB, gives a method for determining the rating from the panel's components. The components that count are the ones in the power circuit, such as the disconnect, the fuses or circuit breakers, motor starters and overload relays, drives, contactors, terminal blocks and power distribution blocks.
Each of those has a short-circuit rating, from the manufacturer's marking or published combination ratings, or a conservative default value from the standard where none is marked. In broad terms, the panel can be rated no higher than its weakest power-circuit component allows, after taking into account any current-limiting protection ahead of that component, and no higher than the interrupting rating of its protective devices.
How component choices raise it
- Current-limiting protection. Current-limiting fuses or circuit breakers ahead of a lower-rated component can raise the rating that component contributes, within the limits the standard sets.
- Tested combinations. Many manufacturers test a drive, starter or other device together with specific fuses or breakers and publish a higher rating for that combination.
- Higher-rated components. Power distribution blocks, terminal blocks and other parts are available with higher ratings, often tied to a specific type or class of protection ahead of them.
These choices are easiest to make while the panel is being designed. Changing them in a finished panel means rework.
How our shop handles SCCR
- Every listed panel from our shop has its short-circuit current rating determined and marked.
- We help customers keep a design within UL 508A, including the fuse and breaker choices that set the SCCR, whether we design the panel or build it to your drawings.
- We also help customers rate their existing panels and choose the fusing or protection to reach a required rating.
- Repairs and modifications can be planned so a panel keeps its certification.
- Our engineering team completed UL's 508A and SCCR training and requalification in 2025. Quality →
What to send
The available fault current where the panel will be installed, or the SCCR your specification requires, together with the voltage. If you don't have the number yet, tell us about the supply and we will ask about the rest. What to send for a panel quote →
Sources: NFPA 70, National Electrical Code, 2023 edition, sections 409.22 and 409.110 (check the edition your jurisdiction has adopted); UL 508A, Supplement SB. This page is general information, not a substitute for the standard or for your inspector's requirements.