Circuit Breakers...when do I need more?

[Gary C]

Okay...I'm very lost on this one I just bought the following for my boat (Catalina 30'):Simrad AutopilotDepth SounderKnotmeterWater pump (for the shower)Nav lights (were previously missing)What do I need to do to power these things? Can I just add them to my current circuit panel (believe there is 6 breakers) or should I install an additional panel? How do I know when I've put too much on a circuit breaker?If I need to install additional breakers, should any of the above be put on there own breaker...or can they be shared? When I go to buy the breakers, what do I get...10A...20A...40A...????I'm sorry for so many questions, I just want to do it correctly.Thanks,Gary Call

 

[Steve]

Volts

Simply put, you need current at the specified voltage (power) to run your new (and old) equipment. The circuit breaker is sized to allow the current you need, but will trip if more is used (IE: a short in the line).Specifically, you will need to size the current draw on the line, and size the circuit breaker AND the wiring to provide the power required. If you have spares, or ones that are not fully used, then you can wire the equipment to those breakers. If not, you will need to add new.From the sounds of it, you have not delt with electrical too much. While you can most likely manage to put the stuff in, I would strongly recommend that you invest in a book as a reference for this. It is much better to do it right the first time than redo it a number of times. I would also recommend that you consider the entire package (batteries, breakers, wiring,

 

[Paul Akers]

Some can be combined

Consider doing the following:Your Simrad Autopilot should have it's own circuit. (Big draw).Your Depth Sounder and Knotmeter can probably be combined on one circuit since they draw so little together.The Water pump (for the shower)can probably be combined on a circuit with the interior lights since it would only be used intermittently. (Moderate draw when used).Your Nav lights (were previously missing)should be on a dedicated circuit. (Moderate draw)

 

[Gary C]

Thanks...can you recommend a good book?

Thank you both for your responses! I'm going to pick up a book so I can be a little more up to speed. I was looking at "Sailboat Electrics Simplified", or "Boat-Owner's Illustrated Handbook of Wiring".Do either of you have any good recommendations?Thanks again!Gary

 

[Paul Akers]

Water Pump??

I was asuming that the water pump is to pump out the shower sump. This can be combined as indicated.But if you are speaking of the pressure water pump to the sinks or shower, then it should be on a dedicated circuit because of the amount of power draw that pump has.

 

[Dave Koirtyohann]

Get some professional help

Unless you have some electrical background and some experience in designing and installing electrical circuits and equipment I'd leave a large installation such as this to a professional.If you decide to go it alone read and heed the installation manuals for these pieces of equipment first. Such things as wire size, routing, circuit loads can drastically effect how you do your installation.

 

[Ron]

Some slightly misleading info given

Circuits are protected at the Circuit Breaker (or fuse) panel to ensure the maximum short circuit current drawn will not exceed the current/heat dissipation rating of the WIRING installed. Devices on a circuit are protected at each device by a fuse, circuit breaker, fuselink, etc. to ensure the maximum current drawn will not damage the DEVICE.The advice about what devices to put onto which protected circuit was pretty good. Most instruments (e.g., depth, speed, wind) operate together in a complementary manner, draw little current, and can be on a common circuit. An Autopilot or RADAR can have a higher current draw, and are needed only intermittently, so they would be on separate circuits. Ditto for each radio (VHF, SSB). Things like pumps (e.g., Pressure Water, Macerator, Bilge, shower drain) and winches usually each have separate circuits -- you don't want one to blow the CB leaving you without the services of the others (especially the Bilge pump!).In addition to selecting the properly sized

 

[Ray]

Gary, The current West Marine catalog has 6

books dealing with elctrical matters with Nigel Calder's being one of the best. It also includes alot of mechanical info about many other boat systems.I found it to be very helpful as a resource to understand many of the issues discussed on this form.RayS/V Speedy