Cute Ammeters

[Mike90250]

The fuse needs to be close to the battery to protect the wires. Having 15 feet of unprotected wire misses the point of a fuse as a protection device.

[-TX-]

So, no attaboy

I'll do that. Easy enough because I have it running to my bank fusebox, just not on a fuse. I was afraid the added circuitry of the fusebox would affect the meter's readings, but I see now that it doesn't. The AC meter (shown) is running off a 20 circuit breaker so I guess I'm good there.

[Mike90250]

Anything running from a 20A breaker, needs to safely handle 20A, so that would need a 12ga wire

[foo1bar]

Anything running from a 20A breaker, needs to safely handle 20A, so that would need a 12ga wire

There are many lamps and other appliances that are on a 20A breaker have smaller wire than 12AWG and are UL listed.
So 12AWG isn't the minimum necessary.
I'm not sure NEC (which is where the 12AWG for 20A originates from) actually applies to an RV. (I don't know if there is a code - there's probably a standard for autos but my guess is no law enforcing it unlike AHJ's adopting the code as law)
12AWG or putting a 10A fuse on a 16AWG wire is what I would do - but it may be possible to justify smaller AWG for a given fuse/breaker protection since it is an automotive application.

[SunEagle]

There are many lamps and other appliances that are on a 20A breaker have smaller wire than 12AWG and are UL listed.
So 12AWG isn't the minimum necessary.
I'm not sure NEC (which is where the 12AWG for 20A originates from) actually applies to an RV. (I don't know if there is a code - there's probably a standard for autos but my guess is no law enforcing it unlike AHJ's adopting the code as law)
12AWG or putting a 10A fuse on a 16AWG wire is what I would do - but it may be possible to justify smaller AWG for a given fuse/breaker protection since it is an automotive application.

If you look at a lot of the automobile wiring it is smaller than 12awg or even 16awg. Check out the fuse ratings and they get down to 1amp in most places which mean the wire is pretty tiny or can easily handle the DC load like the lights or electronics found in a car.

[Sunking]

There are many lamps and other appliances that are on a 20A breaker have smaller wire than 12AWG and are UL listed.
So 12AWG isn't the minimum necessary.
I'm not sure NEC (which is where the 12AWG for 20A originates from) actually applies to an RV. (I don't know if there is a code - there's probably a standard for autos but my guess is no law enforcing it unlike AHJ's adopting the code as law)
12AWG or putting a 10A fuse on a 16AWG wire is what I would do - but it may be possible to justify smaller AWG for a given fuse/breaker protection since it is an automotive application.

You keep me busy correcting you all the time.

Automotive does use a different tables because the insulation type they use is rated much higher temperature than those types use for building power and lighting wire. RRH-2, THHN-2 and quite a few others are rated 90 degree C. Automotive and Marine use 105 degree insulation which means they can run more current. However when we are talking low voltage application you throw the table away in most cases because you need to keep voltage drop to 3% or less.

For RV's it is best to use Marine Standards and Tables which take Voltage Drop, In/Out of Engine Compartment, and How Many Conductors are Bundled Together into consideration. Ironically you end up pretty much where the NEC ends up. Here is a very good web site that sums it up. Note that with a 20 amp fuse the minimum is 14 AWG and @ 3% voltage drop is limited to 6-feet one-way wire distance. That same 20-Amp breaker can be as large as 1 AWG @ 130 feet. It is so simple anyone can use it.

Having said all that this whole discussion is ignorant. His panel meter uses milli-amps. All it needs a 1-Amp fuse using the smallest power panelboard wire allowed which is 18 AWG wire. If there is a direct fault, just a little pop and no damage.

[foo1bar]

You keep me busy correcting you all the time.

Ok - so if you're "correcting" me I must have gotten something wrong.
What did I say that was incorrect?
I don't see anything in the rest of your post that's contradicting what I said.

And I don't think I'm keeping you very busy since the last time we were on the same discussion was a month ago - and that was me correcting your misinformation about Cook County.

Having said all that this whole discussion is ignorant. His panel meter uses milli-amps. All it needs a 1-Amp fuse using the smallest power panelboard wire allowed which is 18 AWG wire. If there is a direct fault, just a little pop and no damage.

I agree he could use a 1A fuse instead of a 10A. I think the vast majority of potential issues would be covered by 10A and there'd be very few cases where you'd see a 1A fuse blow and protect things in this case where a 10A fuse wouldn't blow. So it's not a huge gain in safety I think - but with no difference in cost between putting in a 1A vs. a 10A fuse, he might as well do a 1A fuse.

[Sunking]

Here you go. 14 AWG is as small as you can go on a 20 -amp breaker using 105 degree insulation. If you use 90 degree insulation is 12 AWG. Only exception is on motor circuits under engineers supervision.

What you left out was the most important part. Wire Insulation Type. NEC only goes to 90 degrees in the tables. Auto and Marine uses 105 degree. What is below is Marine. Makes life real simple, meets or exceeds NEC. You cannot go wrong using the table.

It is even color coded so you know which dies to use on the crimper.

[foo1bar]

Here you go. 14 AWG is as small as you can go on a 20 -amp breaker using 105 degree insulation. If you use 90 degree insulation is 12 AWG. Only exception is on motor circuits under engineers supervision.

This table/chart is for marine (boat) use - not automotive/RV.
And I don't think it contradicts what I've said.
If you find an automotive standard that says 12AWG is minimum required for 20A I would say that would legitimately be a correction to what I said.
From what I can find there isn't an automotive (or RV) standard that says that.
And what I can find like this: https://www.tessco.com/yts/industry/...get_wired.html shows 16AWG is OK for a 10' long 20A circuit.
(Wouldn't be what I'd do - but I've already stated what I would do)

And now I have to correct you.
There are MANY more exceptions to using smaller than 12AWG on a 20A circuit.
Look around your house and it is likely that there are MANY appliances that are using a 20A circuit but have 14, 16, or even 18AWG wires and don't have any other over-current protection device.
My old clock radio used 16 or 18AWG.
My lamps are mostly 18AWG. (and they're UL listed/approved).
I think even my washing machine has a smaller than 12AWG wiring - and with it's motor it's using a decent amount of power.

[DanS26]

Here's my "cute" system. I use this setup to monitor my generator output during utility outages to balance the split phase loads. Frequency on top, then Phase A, then Phase B.

Gen Monitor System.JPG

By the way guys, I protected this system with 0.5 amp fast blow fuses and wired it up with 22 ga solid wire reused from florescence lighting fixtures left over from converting to LED.

4 foot LED strips are just the nuts....love the lighting and no more florescence buzzing and delay in cold weather.

[Sunking]

This table/chart is for marine (boat) use - not automotive/RV.

You are correct. Marine Standards exceed automotive. Automotive or SAE accepts 10% voltage loss, while Marine list at 10% and 3%. So if you accept 10% voltage loss as acceptable and defend it, well then you are a HACK. Like I said for low voltage you design for Voltage Loss a point that appears to be way above your head. I never said you have to use 12 AWG on a 20 amp circuit. I said in a NEC application it is required to use a minimum 12 AWG conductor on a 20 amp circuit with a 90 degree cable rating no questions asked. If you meet certain conditions like a motor circuit or high temp wire,you can use 14 AWG on a 20 amp circuit with 60 degree insulation. But not for any solar application in a building.

In fact in NEC you are allowed to run up to 55 amps on 12 AWG if you use 200 degree celsius insulation and have no minimum voltage drop requirement to meet or care about. Thus is why Automotive or SAE specify 105 and 125 degree silicone rubber insulation degree insulation you keep failing to mention with a SLOPPY 10% voltage drop.

The Marine Table I posted is Safe, meets or exceeds all known standards, and very easy for anyone to use, even you. In fact is now a Sticky Post to answer all wire size questions. . How many stickies do you have posted?

And I don't think it contradicts what I've said.
If you find an automotive standard that says 12AWG is minimum required for 20A I would say that would legitimately be a correction to what I said.
From what I can find there isn't an automotive (or RV) standard that says that.

You are right, it is 14 AWG. Look for yourself. If you use 14 AWG and run 20 amps, at 14-feet 1-way you incur 10% voltage and power loss. Unacceptable.

And now I have to correct you.
There are MANY more exceptions to using smaller than 12AWG on a 20A circuit.
Look around your house and it is likely that there are MANY appliances that are using a 20A circuit but have 14, 16, or even 18AWG wires and don't have any other over-current protection device.
My old clock radio used 16 or 18AWG.
My lamps are mostly 18AWG. (and they're UL listed/approved).
I think even my washing machine has a smaller than 12AWG wiring - and with it's motor it's using a decent amount of power.

You are full of crap. Are you that Ignorant? You are stating Appliance Apparatus wiring standards under UL regulations. Again completely forgetting about Cable Insulation temps, voltage drop, and the authority of jurisdiction.

Look dud I am a Professional Engineer of 40 years working with codes and standards. Even sat on NEC code panel for 6 years. How about you? You will loose any code or standard argument with me. Give it up dude.

[-TX-]

This table/chart is for marine (boat) use - not automotive/RV.
And I don't think it contradicts what I've said.
If you find an automotive standard that says 12AWG is minimum required for 20A I would say that would legitimately be a correction to what I said.
From what I can find there isn't an automotive (or RV) standard that says that.
And what I can find like this: https://www.tessco.com/yts/industry/...get_wired.html shows 16AWG is OK for a 10' long 20A circuit.
(Wouldn't be what I'd do - but I've already stated what I would do)

And now I have to correct you.
There are MANY more exceptions to using smaller than 12AWG on a 20A circuit.
Look around your house and it is likely that there are MANY appliances that are using a 20A circuit but have 14, 16, or even 18AWG wires and don't have any other over-current protection device.
My old clock radio used 16 or 18AWG.
My lamps are mostly 18AWG. (and they're UL listed/approved).
I think even my washing machine has a smaller than 12AWG wiring - and with it's motor it's using a decent amount of power.

For all intents and purposes, this RV is a home. A small home, no doubt, but it's wired with romex just as a house would be.

I own a home and treat this thing's AC circuitry the exact same way. Except for grounding issues while on the road, it is the same.

[foo1bar]

You are correct. Marine Standards exceed automotive. Automotive or SAE accepts 10% voltage loss, while Marine list at 10% and 3%. So if you accept 10% voltage loss as acceptable and defend it, well then you are a HACK.

Voltage loss isn't a concern in this application and you know it.
So it appears you're just using that to puff yourself up.

I said in a NEC application ...

Yeah, that's all nice and good - and irrelevant to actually contradicting anything I said.

The Marine Table I posted is Safe, meets or exceeds all known standards

And that's the thing - in some cases it exceeds other standards.

How many stickies do you have posted?

again - irrelevant.

You are right, it is 14 AWG. Look for yourself. If you use 14 AWG and run 20 amps, at 14-feet 1-way you incur 10% voltage and power loss. Unacceptable.

So you can find a table on the internet that almost supports your case (doesn't actually say OCPD or fuse or breaker)
There are a lot that don't support your case:

https://www.swe-check.com.au/pdfs/library1.pdf

http://bdfuses.com/fusesnwires.php

https://www.westmarine.com/WestAdvisor/Marine-Wire-Size-And-Ampacity

https://www.tessco.com/yts/industry/products/itm/automotive/get_wired.html

I didn't find any standards from SAE or similar - but feel free to point me to one.

You are full of crap.

And yet you can't actually quote a line of mine that is factually incorrect with a reference to back it up.
Who's full of crap?

You are stating Appliance Apparatus wiring standards under UL regulations.

YOU asserted that it's simply unacceptable under any circumstances to use less than 12AWG on a circuit with 20A OCPD.
I am pointing out that isn't the case and there are many counterexamples which are certified/approved by an organization which has safety as one of their primary goals.

[quote] and the authority of jurisdiction.[/qoute]
And what AHJ has jurisdiction over an RV?
Seriously - which one?
From what I can tell in the terms used by NEC there isn't one.

Look dud I am a Professional Engineer of 40 years working with codes and standards. Even sat on NEC code panel for 6 years. How about you? You will loose any code or standard argument with me. Give it up dude.

And yet you still haven't actually shown a quote from me that is factually incorrect.

[Sunking]

foo1bar no point in debating. You do not know the difference between Branch Supply circuits and a Power Cord or Apparatus. It is above your pay grade.

[foo1bar]

foo1bar no point in debating.

I'm not debating - I'm correcting your factually inaccurate statements and challenging you to back up with references the BS you're posting.

You do not know the difference between Branch Supply circuits and a Power Cord or Apparatus.

I do know the difference.
What I don't know is why you think that's relevant for an RV's 12V system.

It is above your pay grade.

Ah yes - rather than provide references to support your assertion that I am wrong you resort to insults.