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I’m building household electrical distribution boards where the LED lighting controllers take 24V. To this end I am using a DIN rail-mounted 220-to-24V converter. I connect this converter to controllers using 1mmsq (approx AWG16) wires, which normally requires 6-10A circuit breakers.

My question: which circuit breakers should I use for this? From what I understand, ordinary AC breakers (designed for 230V) work fine on DC but the response characteristics are lengthened. I also know that DC-specific circuit breakers exist. Are they worth using or am I overthinking this?

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    \$\begingroup\$ Are the 230VAC circuit breakers rated for 24VDC? If not then you have to use breakers rated for 24VDC. If you are going to sell these, you as the manufacturer are responsible for safety and compliance with local laws and electric codes. \$\endgroup\$
    – Justme
    Jul 25, 2022 at 19:44
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    \$\begingroup\$ Breakers in electrical panel is for protecting wires from catching fire. Your device may have protected from overcurrent output so additional protection may not be necessary. \$\endgroup\$
    – user263983
    Jul 25, 2022 at 19:46
  • \$\begingroup\$ @Justme the spec sheet says that rated operational voltage is 230/400 whereas operational voltage (without the word rated) is between 12VDC and 72VDC. \$\endgroup\$
    – Dmitri Nesteruk
    Jul 25, 2022 at 19:54
  • \$\begingroup\$ @user263983 the problem is that I use one 24V output on a bus bar shared between several different devices. \$\endgroup\$
    – Dmitri Nesteruk
    Jul 25, 2022 at 19:54
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    \$\begingroup\$ In practice a 230VAC breaker will always work at 24VDC. If you were asking about say 150VDC I’d be worried about the continuous arc, but your only problem is the electrical code. \$\endgroup\$
    – Navin
    Jul 28, 2022 at 6:02

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There is no reason to have problems using breakers rated for a higher AC voltage.

DC powered LED controllers will normally control the current by PWM at some rate to match the average current and therefore % max brightness on demand. There may be a decoupling capacitor on the input to reduce transient EMI on PWM switching but will create a surge current to charge due to V/ESR=I for some T=(Rs+ESR)C= xxx microseconds in duration. It is not much different than driving a motor with a low DCR. The main difference is the stored energy will not arc like an operating motor when disconnected and with DC there is no zero-crossing so there is no turn-off arc or necessary zero cross quenching of breaking current even if the load cuts out before or after disconnect.

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  • \$\begingroup\$ Breakers need for protection wires from overheating. OP asks if AC rated breakers can be used for DC. \$\endgroup\$
    – user263983
    Jul 26, 2022 at 2:44

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