Circuit Breaker amp requirement

[Phil23]

What amp circuit breaker is required for 70amp switch gear on a 12v DC system.
Thank you.

 

[MikeD]

What type of load are you switching?

 

[Phil23]

I am about to install a 70amp Cole Hersee reversing solenoid to convert my capstan. Current circuit breaker has handled capstan load previously but just checking to ensure I do the right thing.I think current circuit breaker/fuse is 250amp

 

[MikeD]

I think you will be Ok with your current CB, but I would look carefully at the motor specifications for the capstan. The starting current is likely to be much higher than the running current.

 

[DavidM]

Generally circuit breakers are sized to protect the wire downstream as a primary consideration and the appliance that they serve secondly. Most windlasses are wired with very large wire to minimize voltage drop but the windlass motor needs less than 90 amps so they are typically installed with a 75-90 amp breaker.

If you have an existing circuit breaker (which I doubt is 250 amps) then you don't need another one.

David

 

[Doug]

This link may be helpful. https://www.bluesea.com/resources/96

 

[FF]

My concern would be the solenoid.

If the unit has a monster CB it is to protect the wiring , not the windlass.

Cole Hersey is a fine co and will post ratings for their solenoids.

Much of the rating is the units ability to break a heavy DC load with out destroying the contacts. Usually if not used as a switch under load , a solenoid will pass loads more current than its listed rating.

Explore the site C/H for the limits the solenoid can actually carry.