Editor’s Note: This column was written by Wade Elliott, owner of Washington-based Utility Supply Group, as part of his monthly e-newsletter, “Words from the Wizard of Watts.” To subscribe for free you can click here.
This month we’re changing it up a bit and taking a question from a ‘Wizard of Watts’ reader.
Earlier this month we received this great question from Don:
“Why do all RV pedestals use the breaker as a switch? Shouldn’t they have a disconnect switch so the breaker is not weakened by constant use?”
Dear Disconnect Don,
The breaker used in an RV pedestal is used as a disconnecting device and as an over current device. This comes in handy when upkeep needs to be done on the circuit or an overload is present. When this happens, the electromagnet circuit and a spring turns the circuit breaker off automatically and the only thing you need to do to restore power (once the problem has been fixed) is to reset and turn the circuit breaker back on. By combining the two you have a cost-effective practical device.
The other option is a fused disconnect. The fused disconnect is a combination of a switch to disconnect the circuit and a fuse to provide over-current protection in the event of a problem. So, why don’t we have the option to get either or? This is where the practicality of the breaker comes into play. The fused disconnect requires a fuse to restore power. Fuses are available in multiple sizes and ratings. Standard fuses can react quickly to over-current situations, breaking the circuit almost immediately, while slow-burning fuses can handle high currents for short intervals, which can be useful to handle the in-rush current of motors when they first start.
Fused disconnects are typically used in high current applications and use a fuse for over current protection. Because they are used in high current applications, they are expensive as they need to carry higher currents, therefore beefier.
Even though circuit breakers and fused disconnects both serve the same general purpose, to open circuits in the occurrence of an overload or short circuit, breakers are still more cost effective and practical. Breakers typically have an expected service life of thousands of on-off cycles. Breakers can also provide ground fault and arc fault protection. Ground fault protection for 15- and 20-amp circuits used outdoors and in wet locations (bathrooms, kitchens, etc.) are important in RV park applications. Arc fault is not normally used in RV site equipment.
Back in the ‘dark ages’ RV pedestals had fuses. But like most things in life, especially in the electrical field, innovation found a more practical way to safeguard our pedestals (and ourselves). It’s interesting to think about what the next great innovation to these pedestals might be.
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