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Old 05-04-2016, 11:22 AM   #1
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Outlet wire runs 14/3 vs 12/3

34' boat with a 30A shore power service. Several AC outlet runs are solid core romex style residential wire. I'm going to replace with tinned marine wire.

For outlets, am I supposed to use 12/3 or is 14/3 AWG ok? The 14/3 will be much easier to run. I'm not sure if the outlet breaker is 15 or 20A, but the supply run from the generator to the panel is 14/3.

Main breaker on generator is 15A, single phase. Currently only one hot leg is in use, which is a topic for a future thread.

Trying to get as close to ABYC as possible, while DIY when within my ability.

Thanks
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Old 05-04-2016, 11:40 AM   #2
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Go back and check the breaker. 15 amp means 14/3 is OK. 20 amp calls for 12/3. 12/3 isn't really that much harder to run than 14/3.


The breaker for the genset is irrelevant.
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Old 05-04-2016, 01:08 PM   #3
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WesK is correct. But separately you should look at how your genset is wired. If you only need 120V then both legs can usually be wired in parallel to give you 30 amps. You will need to upgrade the 15A breaker to 30A if you do this.


Both the way the genset is set up and the use of Romex type solid wire is weird. Must be some PO installed crap. CHB wouldn't do this at the factory.


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Old 05-04-2016, 01:22 PM   #4
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Nobody ever said, "I wish I had run smaller gauge wire".

The power to the outlet on the end of the cable runs through a power pedestal breaker, a crappy receptacle, a shore power cord (with crappy ends), a crappy boat receptacle, a shore power / generator selector switch, a breaker panel, and finally your new cable. There are more than enough places for voltage loss; don't add you new cable to the equation.

Just my $ .02

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Old 05-04-2016, 01:30 PM   #5
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I only use 14/3 for lighting runs. I would not use 14/3 to power a plug/receptacle. 12/3 being my self imposed minimum. Because, in the future you may need to operate a device (heater?) that pulls a good amount of amperage. OC is right, nobody regrets running wire thats larger than needed.
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Old 05-04-2016, 03:40 PM   #6
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If the existing breaker is 15 amp and you are replacing all the wire, it's only the cost of a new breaker ($15) and the slight additional cost of 12/3 over 14/3 to "upgrade". That way, you can use the toaster and the coffee maker at the same time.
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Old 05-04-2016, 04:23 PM   #7
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Quote:
Originally Posted by winty View Post
34' boat with a 30A shore power service. Several AC outlet runs are solid core romex style residential wire. I'm going to replace with tinned marine wire.

For outlets, am I supposed to use 12/3 or is 14/3 AWG ok? The 14/3 will be much easier to run. I'm not sure if the outlet breaker is 15 or 20A, but the supply run from the generator to the panel is 14/3.

Main breaker on generator is 15A, single phase. Currently only one hot leg is in use, which is a topic for a future thread.

Trying to get as close to ABYC as possible, while DIY when within my ability.

Thanks
The solid copper conductor romex really needs to go.

Does household Romex, even stranded, meet ABYC would be my question?

My Californian is wired with 12/2 marine grade cable throughout. It's round yellow sheathed cable, much like dock power cord, with three insulated conductors (Hot Black, Common White and Ground green). Common residential Romex 12/2 or 14/2 is going to have an insulated black and white conductor and an "uninsulated" Ground conductor. Is this an issue?

That's a question for all you ABYC Guru's. . . . . .
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Old 05-04-2016, 05:01 PM   #8
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QUOTE=Edelweiss;439364]The solid copper conductor romex really needs to go.

Does household Romex, even stranded, meet ABYC would be my question?
NO. Not Marine Grade, no USCG or ABYC approvals. No bare conductor grounding conductors.

My Californian is wired with 12/2 marine grade cable throughout. It's round yellow sheathed cable, much like dock power cord, with three insulated conductors (Hot Black, Common White and Ground green).
This should be labeled 12/3.

Common residential Romex 12/2 or 14/2 is going to have an insulated black and white conductor and an "uninsulated" Ground conductor. Is this an issue?
It is still going to be solid, not Marine Grade, and the ground wire needs to be insulated green.

That's a question for all you ABYC Guru's. . . . . .[/QUOTE
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Old 05-04-2016, 05:25 PM   #9
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Thanks for all the suggestions.

I'm sitting in front of the ABYC tech standards book... Based on my findings, planning to run 14/3 105deg C marine wire to specific outlets, which do not require runs though the engine space. New runs are replacing solid core AC wire which appears to have been installed by PO, not the factory. Locations are, transom outlet, flybridge outlet, additional aft cabin outlet, dedicated inverter to galley outlet. Also adding GFCI to all outlets on board, in series wherever possible.
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Old 05-04-2016, 06:03 PM   #10
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Quote:
Originally Posted by High Wire View Post
QUOTE=Edelweiss;439364]The solid copper conductor romex really needs to go.

Does household Romex, even stranded, meet ABYC would be my question?
NO. Not Marine Grade, no USCG or ABYC approvals. No bare conductor grounding conductors.

My Californian is wired with 12/2 marine grade cable throughout. It's round yellow sheathed cable, much like dock power cord, with three insulated conductors (Hot Black, Common White and Ground green).
This should be labeled 12/3.

Common residential Romex 12/2 or 14/2 is going to have an insulated black and white conductor and an "uninsulated" Ground conductor. Is this an issue?
It is still going to be solid, not Marine Grade, and the ground wire needs to be insulated green.

That's a question for all you ABYC Guru's. . . . . .[/QUOTE
Ahha Some of it is just common sense.

Interesting, In residential wiring, only the "non-grounded" conductors are counted. So 12/3 would be 2 hots black and red, white neutral and the bare ground conductor.

My boat wiring is 38 years old, so probably out of date with modern cable, but it's branded, 3 conductor - marine grade -12 awg.

Thanks for the info
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Old 05-04-2016, 07:37 PM   #11
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At the very least run 12/3 to the galley. A coffee maker and an electric skillet (breakfast?) will max out 14/3.
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Old 05-04-2016, 07:49 PM   #12
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Must be a little gennie to have a 15a breaker and 14/3 output cable. A typical little marine gennie is 5kW, breaker 40A and cable 10/3.
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Old 05-04-2016, 09:48 PM   #13
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example 2 on page 51 is a good example for you.

http://uscgboating.org/regulations/a...ELECTRICAL.pdf

the mothership...

http://uscgboating.org/regulations/a...ELECTRICAL.pdf
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Old 05-04-2016, 10:07 PM   #14
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Must be some PO installed crap. CHB wouldn't do this at the factory.
Don't be so sure. I've seen it before in older boats.
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Old 05-04-2016, 11:05 PM   #15
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Thank you for the link, this is consistent with the ABYC standards book I'm reviewing. Based on the above link, why is 14/3 AWG not large enough to feed a duplex outlet? Breakdown as follows.

•*My shorepower service is 120v 30A one leg. Generator is 3600w single phase, but only one leg is feeding selector switch on panel. However, ignore the generator for now.

• Outlet circuit breaker is either 15A or 20A, TBD, but lets assume 20A.

• Page 41, Table 5A "Allowable Amperage of Conductors of 50 Volts or
More When No More Than 2 Conductors are Bundled"

2 conductors table selected based on this statement, page 50, #4 "If the electrical system is 50 volts or more, determine the number of current carrying conductors
(grounding conductors are not normally current carrying) that will be bundled together. "

Table 5A
14 AWG 105 temp rated = 29.8amp for inside engine space

Unless I'm missing a variable here, 14AWG is 1/3rd more capacity than I need for a 20A max load on the outlets. Yes?

EDIT - less than 1V volt loss from pedestal to end of longest run, outlet at transom. I will meter again tomorrow, but it was so small, that I don't consider increasing cable gauge to compensate for voltage drop as an issue.

I'm not against 12/3 vs 14/3. However, based on all the documentation it doesn't appear necessary.
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Old 05-04-2016, 11:53 PM   #16
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While I only glanced over the table, I didn't see the compensation for length of the cable. Normally 120 vac wiring charts specify a wire size or amperage limit based on the length of the cable. As an example: you can use 10 gauge wire for 30 amps, but not if the length is over 30' (depending on the wire size table).

Ted
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Old 05-05-2016, 12:44 AM   #17
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In order to use the 105c rating for the wire you will also need to use a 105c rated breaker. Best practices are to use #14 wire for a 15a circuit, #12 for a 20a circuit.
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Old 05-05-2016, 06:58 AM   #18
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Irrespective of what the ampacity calculators or charts say, NEC specifies a minimum of 14 gauge wire for a 15 amp breaker and 12 gauge wire for a 20 amp breaker.


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Old 05-05-2016, 07:26 AM   #19
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Many dock power supplies are really sad.

When everyone has air cond on the dock voltage may only be 105 or less.

When a few AC start at once it gets really low.

Treat your appliances to the best juice and have bigger wire in the boat than required.

The downside is cost and a harder install, a one time hit.
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Old 05-05-2016, 09:29 AM   #20
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Don't be so sure. I've seen it before in older boats.
Damn right. I've removed romex from my boat along with cloth insulated wire. Crazy I say. I also removed a type of wire that I've seen in houses from the '20s & '30s. I have one left to remove. Not done it yet, needed a break from the electrical stuff. Holly Molly.
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