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-   -   Refrigerator off main breaker? (http://www.sailnet.com/forums/electrical-systems/104217-refrigerator-off-main-breaker.html)

GrahamO 09-29-2013 07:29 AM

Refrigerator off main breaker?
 
I am just installing a new fridge system. The old one is tied to the main breaker but I am considering going direct from the battery through its own breaker so we could leave it on with the rest of the boat off. Is this OK?

It is for long term cruising and we have a very well insulated (4 1/2"+) refrigerator and 400w of solar.

Advice appreciated as always.

Thanks

Graham

Minnewaska 09-29-2013 07:34 AM

Re: Refrigerator off main breaker?
 
You should have a main breaker that feeds all the sub breakers, for which one could be dedicated to the fridge. Everything else should go through other sub breakers, so that anything can be isolated, but everything can be killed by the one master in the event of an electrical fire.

deniseO30 09-29-2013 09:27 AM

Re: Refrigerator off main breaker?
 
Need, more information! Guessing it's only 5 amps but more importantly; use the right size wire!

mitiempo 09-29-2013 01:57 PM

Re: Refrigerator off main breaker?
 
This is DC so a main breaker is not needed - the house bank main fuse takes care of that before feeding the DC panel. It is common to have a few "always on" circuits, bilge pump for one and the refrigeration can also be one. These are best fed from a sub panel that is not main switch dependent. A small panel or a fuse block works well. The feed wire to this panel or fuse block should be appropriately fused for the wire size leading to it. If desired a switch can be installed in this wire so total isolation is possible.

GrahamO 09-29-2013 03:07 PM

Refrigerator off main breaker?
 
Thanks guys,
I am planning battery to 30amp fuse to 30amp+ switch to refrigerator compressor. The wiring is all oversized as the old fridge was a monster. New one is a Seafrost BDXP air/water.

Graham

Minnewaska 09-29-2013 03:47 PM

Re: Refrigerator off main breaker?
 
Quote:

Originally Posted by mitiempo (Post 1095683)
This is DC so a main breaker is not needed......

Not sure what you mean by not needed. If you mean that separate breakers are not absolutely necessary to safely protect a circuit, I agree.

However, in the event of smelling an electrical fire (the most common form of boat fire), wouldn't you want one master switch to kill it all? In addition, if you're up on the hard or away or just need to kill all parasitic loads, a master is very helpful. That may not be a breaker, but often goes through a kill switch of some kind.

deniseO30 09-29-2013 04:45 PM

Re: Refrigerator off main breaker?
 
Size the breaker per unit specs.. 15 amp.. guessing again..

why is needed information always a secret with people asking for advice?

mitiempo 09-29-2013 07:51 PM

Re: Refrigerator off main breaker?
 
Quote:

Originally Posted by Minnewaska (Post 1095714)
Not sure what you mean by not needed. If you mean that separate breakers are not absolutely necessary to safely protect a circuit, I agree.

However, in the event of smelling an electrical fire (the most common form of boat fire), wouldn't you want one master switch to kill it all? In addition, if you're up on the hard or away or just need to kill all parasitic loads, a master is very helpful. That may not be a breaker, but often goes through a kill switch of some kind.

A main breaker is not needed because the house bank should be fused within 7" of the positive post. That fuse will protect the wire to the main switch and from there to the main DC panel, where each circuit has a breaker or fuse which it must have. Whenever the wire size drops a new fuse is required if the main fuse is below the ampacity of the smaller wire.

As I posted a sub panel or fuse block is often used for "always on circuits" like the bilge pump or refrigeration. I also said a switch can be installed to isolate the sub panel or fuse block if desired. It is a good idea but I rarely see it.

Bene505 09-30-2013 12:20 AM

Re: Refrigerator off main breaker?
 
We use a dedicated fuse for the fridge, wired directly to the battery. Fuses cause less voltage drop than circuit breakers. Our fridge is always on.

Actually, our compressor is well aft, far from the house bank and right near the shore power charger. I use the (now disconnected) shore power charger's wire. It's 6 gauge. Then I have the fridge fuse coming off that, to a short-ish 14 or 16 gauge wire. 5 amps load. Seafrost says to make sure the compressor gets good power.

Regards,
Brad

GrahamO 09-30-2013 01:11 AM

Thanks Brad,
Do you have a switch that allows you to isolate the refrigerator?

Graham

Quote:

Originally Posted by Bene505 (Post 1095979)
We use a dedicated fuse for the fridge, wired directly to the battery. Fuses cause less voltage drop than circuit breakers. Our fridge is always on.

Actually, our compressor is well aft, far from the house bank and right near the shore power charger. I use the (now disconnected) shore power charger's wire. It's 6 gauge. Then I have the fridge fuse coming off that, to a short-ish 14 or 16 gauge wire. 5 amps load. Seafrost says to make sure the compressor gets good power.

Regards,
Brad



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