Wiring type needed for new circuit to bedroom for 2- 12v power point plugs.

[powerscol]

I have a CPAP that can pull 8 amps. I am installing two 12V round power point plugs (used to be cigarette lighter) in the bedroom night stands. I will be putting the second one on the Boss Unit's side for the possibility she will need one too. I am looking at using 12 gauge wire from the battery compartment and inline 30amp fuse to have a separate circuit. Is there a particular type I should be look for. I was looking at 12-2 cable, but most are for speaker wiring. I did find this one though and was wondering if it would be better. http://www.bestboatwire.com/12-2-awg...-blk-red-50-ft

Any advice would help.
Keith

[TucsonJim]

You don't state how long the wire run will be. I know the wire you listed is 50 feet long. To make sure you're specifying the correct wire, some assumptions have to be made.

If you're running two CPAPs at 8 amps each, you'll have a 16 amp draw at times.
Then we need to know the distance from the battery (or other power connection) to the CPAP. Then double that number to get the circuit length.


Using the chart I'm attaching below, you can see that the appropriate column for "current flow in amps" is 20 amps.

If the circuit path distance is 20 feet or less, the correct wire is 14AWG
If the circuit path distance is up to 30 feet, use 12AWG
Up to 50 feet, go with 10AWG.

These are based on a non-critical 10% voltage drop. You can use the chart to see the impact of selecting a 3% voltage drop vs. the wire size.

Normal fuse sizing is 135% of the full load current taken to the next standard size. 16 Amps x 135% = 21.6 Next standard size is a 25 amp fuse. This will provide both short circuit and over-load protection.




Jim

[powerscol]

Well - from the battery to under the bed is about 6'. At that point it will split and run inside the bed frame to the night stands each side. My best guess is each run will be about 8' from the split. I was thinking of the marine wire as it has a second covering and I could use the stick on cable ties to hold it in place inside the bed frame and not need additional protection such as a loom. I chose the 12 awg just in case for this projects and also have the remainder for other projects. As the wire is tinned it will make soldering the connections easier too.

[shanes318]

You don't state how long the wire run will be. I know the wire you listed is 50 feet long. To make sure you're specifying the correct wire, some assumptions have to be made.

If you're running two CPAPs at 8 amps each, you'll have a 16 amp draw at times.
Then we need to know the distance from the battery (or other power connection) to the CPAP. Then double that number to get the circuit length.


Using the chart I'm attaching below, you can see that the appropriate column for "current flow in amps" is 20 amps.

If the circuit path distance is 20 feet or less, the correct wire is 14AWG
If the circuit path distance is up to 30 feet, use 12AWG
Up to 50 feet, go with 10AWG.

These are based on a non-critical 10% voltage drop. You can use the chart to see the impact of selecting a 3% voltage drop vs. the wire size.

Normal fuse sizing is 135% of the full load current taken to the next standard size. 16 Amps x 135% = 21.6 Next standard size is a 25 amp fuse. This will provide both short circuit and over-load protection.




Jim

Is that braided or solid core sizes in the chart? The chart, although a bit blurry, is a great reference. Thanks for posting.


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[Cate&Rob]

This might be a more readable version of the chart . . .

[powerscol]

First thanks to all for the help and the nifty chart. I checked with my CPAP manufacturer and while it can operate at various voltages they do not recommend it. So I did some online shopping for everything I needed and found this place. http://shop.pkys.com/

I decide to go with 10/2 AWG duplex wire and got a 100' roll so I have extra for other projects.http://shop.pkys.com/Ancor-124110-Ti...l-_p_6833.html

I also decided to put in a fuse block for possible future projects. This fuse block has a negative buss bar on it too. http://shop.pkys.com/Blue-Sea-5025-S...ts_p_1619.html

I plan to put a master fuse before the fuse block, then run separate lines to each 12v power plugs I am installing each side the bed. As mentioned GD got me framing information (Excellent Service).

Ill try to do a write up when I get this completed. BTW - I do know this is probably overkill but figured it is a safe bet and should be problem free.

Thoughts

[shanes318]

First thanks to all for the help and the nifty chart. I checked with my CPAP manufacturer and while it can operate at various voltages they do not recommend it. So I did some online shopping for everything I needed and found this place. http://shop.pkys.com/

I decide to go with 10/2 AWG duplex wire and got a 100' roll so I have extra for other projects.http://shop.pkys.com/Ancor-124110-Ti...l-_p_6833.html

I also decided to put in a fuse block for possible future projects. This fuse block has a negative buss bar on it too. http://shop.pkys.com/Blue-Sea-5025-S...ts_p_1619.html

I plan to put a master fuse before the fuse block, then run separate lines to each 12v power plugs I am installing each side the bed. As mentioned GD got me framing information (Excellent Service).

Ill try to do a write up when I get this completed. BTW - I do know this is probably overkill but figured it is a safe bet and should be problem free.

Thoughts

Thanks for the info. We bought a new Reflection back in December and i know we wool be freestanding at Eldora... So I will need to make similar mod. I will watch for the details when you post them.

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