what size wire to use for 30amp 12v circuit ?

The Ancor calculator Matt mentioned is about right. Things to keep in mind
are that a 25 foot length of wire is only good for 12.5 feet of
distance..........out and back, right?

And the type insulation is worth considering, particularly if it's
going to be near any heat, oil, sunlight, etc, etc.

Remember also that under emergency conditions (no alternator turning)
there isn't going to be that comfortable 14.7 volts to fall back on, but
something like 12.3 or 12.4 from a good, recently charged battery. Lots of
high class SSB radios will start jumping frequency or channels with 11 volts
at the radio, and the tuner will also be trying to retune everytime you
holler "Heeeelp" in the mic.

Welding cable is worth considering. Fine, cable laid wire with good
tough neoprene jacketing. Terminals deserve good swedged tools, and wicking
a little solder in after the swedging is super around salt water and
batteries.

Old Chief Lynn
 >> Stay informed about: what size wire to use for 30amp 12v circuit ? 

In article <dsp5jm$j63$1@emma.aioe.org>,
"Lynn Coffelt" <coffelt2.DeleteThis@comcast.net> wrote:

> The Ancor calculator Matt mentioned is about right. Things to keep in mind
> are that a 25 foot length of wire is only good for 12.5 feet of
> distance..........out and back, right?
>
> And the type insulation is worth considering, particularly if it's
> going to be near any heat, oil, sunlight, etc, etc.
>
> Remember also that under emergency conditions (no alternator turning)
> there isn't going to be that comfortable 14.7 volts to fall back on, but
> something like 12.3 or 12.4 from a good, recently charged battery. Lots of
> high class SSB radios will start jumping frequency or channels with 11 volts
> at the radio, and the tuner will also be trying to retune everytime you
> holler "Heeeelp" in the mic.
>
> Welding cable is worth considering. Fine, cable laid wire with good
> tough neoprene jacketing. Terminals deserve good swedged tools, and wicking
> a little solder in after the swedging is super around salt water and
> batteries.
>
> Old Chief Lynn
>
>

I agree with "Old Chief Lynn" here, if the appliance we're discussing
here is an MF/HF SSB Radio. The thing that needs to be understood
is that Battery Voltage at the terminals is NOT Voltage at the back
of the Radio, or at the PowerAmp DC Terminals, especially at the 20
to 25 Amp draw of a 100 to 150 watt Peak Envelope Power Radio.
It is commonly understood that for each volt dropped from 13.6 VDC
at the radios PowerAmp DC Terminals, you lose 50% of your PEP Power.
So if your at 13.6 Vdc you get your 150 PEP, and at 12.6 VDC you
get 75 PEP, and at 11.6 Vdc you get 35 PEP and below 11.0 VDC
the internal Voltage Regulators drop out of regulation and the
radio goes OFF.
So any voltage drop associated with the wiring between the battery and
the radio at the the Demand Input Current of the radio, effects the
available output power. How many times have I seen a radio that receives
perfectly, but dies whenever you press the PTT and modulate the Mic.
LOTS. This is one of the reasons that the Powersupplys for FVSA
(Fishing Vessel Safety ACT) and SOLAS requires that any batteries
used for powering these MF/HF SSB Radios be on or above the same deck
as the Radio, and Battery Condition be certified each year by a
Discharge Test, in the case of SOLAS Required Vessels. When FVSA
was out for Public Comment, there was a bit of a uproar about this
requirment, as no one had that type of power system aboard, but
it was made LAW anyway, and most of the fleet installed the required
battery under the wheelhouse floor, right behind the wheelhouse
on that deck, or on top of the wheelhouse. These locations will
tend to keep the wire runs short, and any installer woirth his Salt,
should and would DOUBLE the wiresize on the MF/HF SSB Radio that
any table stated would be good enough.
Most of the vessels I Inspected had AC PowerSupplies, or DC/DC Converters
running from Ships Power of 120Vac or 32Vdc and Power leads of a foot or
two, before the FVSA, and we just added an 8D battery between the two.

Bruce in alaska
--
add a <2> before @
 >> Stay informed about: what size wire to use for 30amp 12v circuit ? 

Where did you hear that myth??? Iv'e been a marine electronics tech for 30
years and have never heard that one. I know what you stated is total bs but
just for drill I did a little test before leaving work today. Hooked up a
variable power supply to my Icom 735 with a Bird 4381 power analyst in line
(which reads PEP directly). I also verified the wattmeter readings using an
o-scope. The power didn't start to drop til the voltage dropped below 10.5v
and I was able to receive just fine all the way down to 9.5v. Below that the
rig started to die.

Eric

"Bruce in Alaska" <bruceg.RemoveThis@btpost.net> wrote in message
news:bruceg-40498B.10195913022006@netnews.worldnet.att.net...
> It is commonly understood that for each volt dropped from 13.6 VDC
> at the radios PowerAmp DC Terminals, you lose 50% of your PEP Power.
> So if your at 13.6 Vdc you get your 150 PEP, and at 12.6 VDC you
> get 75 PEP, and at 11.6 Vdc you get 35 PEP and below 11.0 VDC
> the internal Voltage Regulators drop out of regulation and the
> radio goes OFF.
 >> Stay informed about: what size wire to use for 30amp 12v circuit ? 

"Eric Fairbank" <fairbank56 DeleteThis @yahoo.com> wrote in news:vvGdna8RzJfu857ZRVn-
iQ DeleteThis @comcast.com:

> Where did you hear that myth???

Old school, Bruce. Still remembers what happened to the tube rigs when the
filament voltage dropped as well as the unregulated vibrator or square-wave
HVPS of old.

If you jumper out the leveling circuit that provides the flat power output
down to 10V on the M-802, she'll put out almost 220 watts until the heat
sink overheats and shuts her down....at 13V. Icom, and the others, have
left plenty of headroom for the power regulators to compensate for a good
bit of DC power loading.

Sure not like the old rigs with the light bulb RF indicators...(c;
 >> Stay informed about: what size wire to use for 30amp 12v circuit ? 

This message is not archived
 >> Stay informed about: what size wire to use for 30amp 12v circuit ? 

In article <vvGdna8RzJfu857ZRVn-iQ.DeleteThis@comcast.com>,
"Eric Fairbank" <fairbank56.DeleteThis@yahoo.com> wrote:

> Where did you hear that myth??? Iv'e been a marine electronics tech for 30
> years and have never heard that one. I know what you stated is total bs but
> just for drill I did a little test before leaving work today. Hooked up a
> variable power supply to my Icom 735 with a Bird 4381 power analyst in line
> (which reads PEP directly). I also verified the wattmeter readings using an
> o-scope. The power didn't start to drop til the voltage dropped below 10.5v
> and I was able to receive just fine all the way down to 9.5v. Below that the
> rig started to die.
>
> Eric
>
> "Bruce in Alaska" <bruceg.DeleteThis@btpost.net> wrote in message
> news:bruceg-40498B.10195913022006@netnews.worldnet.att.net...
> > It is commonly understood that for each volt dropped from 13.6 VDC
> > at the radios PowerAmp DC Terminals, you lose 50% of your PEP Power.
> > So if your at 13.6 Vdc you get your 150 PEP, and at 12.6 VDC you
> > get 75 PEP, and at 11.6 Vdc you get 35 PEP and below 11.0 VDC
> > the internal Voltage Regulators drop out of regulation and the
> > radio goes OFF.
>
>

It is not a Myth, is is a Fact, and as others have stated, your
experiment doesn't prove, or disprove the fact. Also, as Larry
stated the 21st Century Icom Rigs have a lot more headroom in the
SolidState Amps than just about any other Marine MF/HF Radio,
just to deal with this cause. Just try your experiment with ANY
SGC designed and built radio.

Bruce in alaska I am Old School, and an Old Fart, and I do remember
back in the Old Days, before Autotuners, allowed
anyone to think they were World Class Radiomen...
--
add a <2> before @
 >> Stay informed about: what size wire to use for 30amp 12v circuit ? 

> "Eric Fairbank" <fairbank56.DeleteThis@yahoo.com> wrote:
>
> > Where did you hear that myth??? Iv'e been a marine electronics tech
for 30
> > years and have never heard that one. I know what you stated is total bs
but
> > just for drill I did a little test before leaving work today. Hooked up
a
> > variable power supply to my Icom 735 with a Bird 4381 power analyst in
line
> > (which reads PEP directly). I also verified the wattmeter readings using
an
> > o-scope. The power didn't start to drop til the voltage dropped below
10.5v
> > and I was able to receive just fine all the way down to 9.5v. Below that
the
> > rig started to die.
> >
> > Eric
> >
> > "Bruce in Alaska" <bruceg.DeleteThis@btpost.net> wrote in message
> > news:bruceg-40498B.10195913022006@netnews.worldnet.att.net...
> > > It is commonly understood that for each volt dropped from 13.6 VDC
> > > at the radios PowerAmp DC Terminals, you lose 50% of your PEP Power.
> > > So if your at 13.6 Vdc you get your 150 PEP, and at 12.6 VDC you
> > > get 75 PEP, and at 11.6 Vdc you get 35 PEP and below 11.0 VDC
> > > the internal Voltage Regulators drop out of regulation and the
> > > radio goes OFF.
> >
> >
>
> It is not a Myth, is is a Fact, and as others have stated, your
> experiment doesn't prove, or disprove the fact. Also, as Larry
> stated the 21st Century Icom Rigs have a lot more headroom in the
> SolidState Amps than just about any other Marine MF/HF Radio,
> just to deal with this cause. Just try your experiment with ANY
> SGC designed and built radio.
>
> Bruce in alaska I am Old School, and an Old Fart, and I do remember
> back in the Old Days, before Autotuners, allowed
> anyone to think they were World Class Radiomen...
> --
Oh, my gosh, it's just killing me to sit here without jumping in! Then
when I heard SGC mentioned, I knew that someone besides me had experienced
"Bruce's Law". I am compelled to defend his position and scientific
observations without reservation.

How much midnight oil I've spent working on the DC supply system on
"commercial" vessels, trying to reduce the voltage drop. Until the "code"
made batterys in the pilot house almost mandatory, can't you imagine running
an SGC711 from engine room batterys? Here's a typical example (it is a
genuine "commercial", by the way) of a vessel still using this one time
popular rig:

http://www.alaskaboat.com/sn033.htm

Those SGC711's were hard to coax to even 75 watts PEP with any wire
less than #4 if you were more than two feet away from the battery! (OK,
stretching a little here) And the built-in wire antenna tuner was a charmer,
hey? But as the URL and dozens more can show, that not everyone has yet to
install an Icom M802.

Some earlier SEA's and Icom's with first generation digital VCO tuning
were cool, too. A sneeze or laugh in the mic was as apt to change channels
as anything if the antenna was fed directly from the radio, and some joker
installed #10 wire for DC power!

Early automatic antenna tuners were (are) cool, too. A little pitching
and rolling in the North Pacific and they would lock up and refuse to even
try to tune anymore. Then the transmitter's fabulous SWR power foldback
circuit hit the fan and 5 to 10 watts could be used to heat up the tuner's
coils and capacitors. (condensers, actually)

Lots of this early stuff is still out there. By the thousands. Modern
marine SSB radios certainly have improved their ability to survive poor
installations, but is that any reason to go as cheap as possible with DC
wiring and antenna installations? (RF ground on "Tupperware" boats is
probably just as important, but I digress)

Old Chief Lynn

(besides, tubes help heat the pilothouse and ease aching joints)
 >> Stay informed about: what size wire to use for 30amp 12v circuit ? 

Lynn Coffelt wrote:
>> "Eric Fairbank" <fairbank56.TakeThisOut@yahoo.com> wrote:
>>> Where did you hear that myth??? Iv'e been a marine electronics tech for 30
>>>years and have never heard that one. I know what you stated is total bs but
>>>just for drill I did a little test before leaving work today. Hooked up a
>>>variable power supply to my Icom 735 with a Bird 4381 power analyst in line
>>>(which reads PEP directly). I also verified the wattmeter readings using an
>>>o-scope. The power didn't start to drop til the voltage dropped below 10.5v
>>>and I was able to receive just fine all the way down to 9.5v. Below that the
>>>rig started to die.
>>>
>>>Eric
>>>
>>>"Bruce in Alaska" <bruceg.TakeThisOut@btpost.net> wrote in message
>>>news:bruceg-40498B.10195913022006@netnews.worldnet.att.net...
>>>
>>>>It is commonly understood that for each volt dropped from 13.6 VDC
>>>>at the radios PowerAmp DC Terminals, you lose 50% of your PEP Power.
>>>>So if your at 13.6 Vdc you get your 150 PEP, and at 12.6 VDC you
>>>>get 75 PEP, and at 11.6 Vdc you get 35 PEP and below 11.0 VDC
>>>>the internal Voltage Regulators drop out of regulation and the
>>>>radio goes OFF.
>>>
>>It is not a Myth, is is a Fact, and as others have stated, your
>>experiment doesn't prove, or disprove the fact. Also, as Larry
>>stated the 21st Century Icom Rigs have a lot more headroom in the
>>SolidState Amps than just about any other Marine MF/HF Radio,
>>just to deal with this cause. Just try your experiment with ANY
>>SGC designed and built radio.
>>
>>Bruce in alaska I am Old School, and an Old Fart, and I do remember
>> back in the Old Days, before Autotuners, allowed
>> anyone to think they were World Class Radiomen...
>>--
>
> Oh, my gosh, it's just killing me to sit here without jumping in! Then
> when I heard SGC mentioned, I knew that someone besides me had experienced
> "Bruce's Law". I am compelled to defend his position and scientific
> observations without reservation.
>
> How much midnight oil I've spent working on the DC supply system on
> "commercial" vessels, trying to reduce the voltage drop. Until the "code"
> made batterys in the pilot house almost mandatory, can't you imagine running
> an SGC711 from engine room batterys? Here's a typical example (it is a
> genuine "commercial", by the way) of a vessel still using this one time
> popular rig:
>
> http://www.alaskaboat.com/sn033.htm
>
> Those SGC711's were hard to coax to even 75 watts PEP with any wire
> less than #4 if you were more than two feet away from the battery! (OK,
> stretching a little here) And the built-in wire antenna tuner was a charmer,
> hey? But as the URL and dozens more can show, that not everyone has yet to
> install an Icom M802.
>
> Some earlier SEA's and Icom's with first generation digital VCO tuning
> were cool, too. A sneeze or laugh in the mic was as apt to change channels
> as anything if the antenna was fed directly from the radio, and some joker
> installed #10 wire for DC power!
>
> Early automatic antenna tuners were (are) cool, too. A little pitching
> and rolling in the North Pacific and they would lock up and refuse to even
> try to tune anymore. Then the transmitter's fabulous SWR power foldback
> circuit hit the fan and 5 to 10 watts could be used to heat up the tuner's
> coils and capacitors. (condensers, actually)
>
> Lots of this early stuff is still out there. By the thousands. Modern
> marine SSB radios certainly have improved their ability to survive poor
> installations, but is that any reason to go as cheap as possible with DC
> wiring and antenna installations? (RF ground on "Tupperware" boats is
> probably just as important, but I digress)
>
> Old Chief Lynn
>
> (besides, tubes help heat the pilothouse and ease aching joints)
>
Let's just watch out here. I was in a junk shop a while ago and I told
the proprietor what was actually hoping to find. We got talking about
ships and boats. He stopped and asked if I could tell him about
something in back. When retrieved, it turned out to be a marine HF -
real live dinosaur (dynosoar?). I think is was Hammerlund or EF Johnson
- most of the crystals had been pulled, but it still had a the 2 1625s
in the final (and a little burned spot on the tank). I looked at him
and said "You know - They haven't made 'em like this for a long time".
(Aren't we glad!)

Matt Colie - Lifelong Waterman, Licensed Mariner and Perpetual Sailor
 >> Stay informed about: what size wire to use for 30amp 12v circuit ? 

So, now your saying your theory only applies to certain radios? Then you
shouldn't make blanket statements like you did. You mislead the average joe
who reads this newsgroup. It is not common knowledge and while it may be a
"fact" for "one" radio, it is certainly not a "fact" in general. I disproved
your statement on the Icom 735, and today I disproved it on the SEA222,
Icom-710, Icom-802, SEA235 and a Yaesu FT-897. I'm not disputing the fact
that minimizing voltage drops on an HF installation is of prime importance.
I just think you are way out of line making such a statement and claiming it
as a commonly understood fact.

Eric

"Bruce in Alaska" <bruceg.TakeThisOut@btpost.net> wrote in message
news:bruceg-C00779.10144528022006@netnews.worldnet.att.net...
>> > It is commonly understood that for each volt dropped from 13.6 VDC
>> > at the radios PowerAmp DC Terminals, you lose 50% of your PEP Power.
>> > So if your at 13.6 Vdc you get your 150 PEP, and at 12.6 VDC you
>> > get 75 PEP, and at 11.6 Vdc you get 35 PEP and below 11.0 VDC
>> > the internal Voltage Regulators drop out of regulation and the
>> > radio goes OFF.
>>
>>
>
> It is not a Myth, is is a Fact, and as others have stated, your
> experiment doesn't prove, or disprove the fact. Also, as Larry
> stated the 21st Century Icom Rigs have a lot more headroom in the
> SolidState Amps than just about any other Marine MF/HF Radio,
> just to deal with this cause. Just try your experiment with ANY
> SGC designed and built radio.
 >> Stay informed about: what size wire to use for 30amp 12v circuit ? 

Bruce in Alaska <bruceg.RemoveThis@btpost.net> wrote in news:bruceg-
C00779.10144528022006.RemoveThis@netnews.worldnet.att.net:

> Just try your experiment with ANY
> SGC designed and built radio.
>

Whoa! Hang on! You'd never get an SGC out of the shop long enough to
complete the experiment! That wouldn't be fair....(c;

SGC SUCKS! Ask any ham....(c;
 >> Stay informed about: what size wire to use for 30amp 12v circuit ? 

"Bruce in Alaska" <bruceg DeleteThis @btpost.net> wrote in message
news:bruceg-C00779.10144528022006@netnews.worldnet.att.net...
> It is not a Myth, is is a Fact, and as others have stated, your
> experiment doesn't prove, or disprove the fact. Also, as Larry
> stated the 21st Century Icom Rigs have a lot more headroom in the
> SolidState Amps than just about any other Marine MF/HF Radio,
> just to deal with this cause.

But.... it is also a fact that any modern rig that is also allowed on
commercial vessels (IEC/EN60945) will never show this behavior, otherwise
they wouldn't be able to pass the the tests to comply with that standard.

Meindert
 >> Stay informed about: what size wire to use for 30amp 12v circuit ? 

In article <taKdnRHvnovLdJnZRVn-pg DeleteThis @comcast.com>,
"Eric Fairbank" <fairbank56 DeleteThis @yahoo.com> wrote:

> So, now your saying your theory only applies to certain radios? Then you
> shouldn't make blanket statements like you did. You mislead the average joe
> who reads this newsgroup. It is not common knowledge and while it may be a
> "fact" for "one" radio, it is certainly not a "fact" in general. I disproved
> your statement on the Icom 735, and today I disproved it on the SEA222,
> Icom-710, Icom-802, SEA235 and a Yaesu FT-897. I'm not disputing the fact
> that minimizing voltage drops on an HF installation is of prime importance.
> I just think you are way out of line making such a statement and claiming it
> as a commonly understood fact.
>
> Eric

Eric, just how did you disprove this? Using the same setup that you
used in your original experiment? Well, now, why don't you try modifing
your setup and put 30Ft of #14 Wire from your very stiff powersupply to
the radios.
Now try the putput power test again, and come back and tell us all
what you find.

You see Bill Forgey, the Retired Chief Engineer at SEA, and I, did all
of these experiments years ago in the SEA Engineering LAB, and concluded
that yes, this was the case. One of the reasons that more headroom in
the HF Amplifier sections was a prime design factor in the SEA 322-330
Series Radios, but which still did not completely resolve the problem of
trying to operate a 20+ amp Current draw, thru a less than steller
Power Wire.


Bruce in alaska
--
add a <2> before @
 >> Stay informed about: what size wire to use for 30amp 12v circuit ? 

I'm just shaking my head here Bruce. You keep changing your story. I
disagree with your original blanket statement which was not in reference to
old SGC rigs or installations with 30ft of #14 wire. Jeez!

Eric

"Bruce in Alaska" <bruceg DeleteThis @btpost.net> wrote in message
news:bruceg-5AAC28.10465801032006@netnews.worldnet.att.net...
> Eric, just how did you disprove this? Using the same setup that you
> used in your original experiment? Well, now, why don't you try modifing
> your setup and put 30Ft of #14 Wire from your very stiff powersupply to
> the radios.
> Now try the putput power test again, and come back and tell us all
> what you find.
>
 >> Stay informed about: what size wire to use for 30amp 12v circuit ?