[boomer]

I have seen a few schematics where multiple pieces of electric equipment are wired to the same circuit breaker. If my memory is correct, one of the examples from Vans does this. Does anyone have a rule of thumb on when this is appropriate and how to compute the circuit breaker rating? Thanks.

 

[Brantel]

The circuit breaker is there to protect the wire not the device.

That being said, if you combine wires on one breaker, each wire connected must be able to handle current equal to the rating of the breaker.

As far as how to size, sum up the loads and treat them as one...

 

[bharral]

Combining loads on a single circuit breaker

The circuit breaker is there to protect the wire not the device.

That being said, if you combine wires on one breaker, each wire connected must be able to handle current equal to the rating of the breaker.

As far as how to size, sum up the loads and treat them as one...

You should additionally consider the following:

Supplying two or more pieces of equipment from the same breaker means that a fault in one piece of equipment or wiring can effectively depower the remaining device. You need to decide if this is acceptable. It may be acceptable if neither piece of equipment is critical, and they are not intended to serve as backups for one another.

Regards,
Blake Harral
RV-4 N72RV

 

[az_gila]

I know Part 23 does...

You should additionally consider the following:

Supplying two or more pieces of equipment from the same breaker means that a fault in one piece of equipment or wiring can effectively depower the remaining device. You need to decide if this is acceptable. It may be acceptable if neither piece of equipment is critical, and they are not intended to serve as backups for one another.

Regards,
Blake Harral
RV-4 N72RV

...not apply to our planes, but this sentence out of 23.1537 does make sense... just like Blake says --

(b) A protective device for a circuit essential to flight safety may not be used to protect any other circuit.

..and so does the spare fuse bit of the whole section --

http://rgl.faa.gov/Regulatory_and_G...7617A58441097A728525668700722013?OpenDocument

 

[boomer]

Thanks for the good info. I bit the bullet and bought separate CB's for each piece of equipment.

-John