12v Sockets

[IdahoMan]

Just how much smaller is GXL than SXL?

I have a sample of 10ga THHN building wire and it is identical to my 12ga SXL wire in total size. And the THHN seems much harder to strip than the SXL, but the crosslink was recommended for automotive wiring.

Also, the largest GXL size available appears to be 8ga from WireBarn.

[bd]

Although rated for 600 volts, PVC insulated/nylon jacketed THHN hasn't the same abrasion resistance of cross-linked wire and may not possess as high a strand count for flexibility.  In addition, THHN is generally intended to be routed inside protective conduit.

The difference in OD between SXL and GXL is nominal - perhaps a few percent.  The 6-gauge GXL @ Terminal Supply Co maybe the heaviest gauge cross-linked polyethylene easily available.

[IdahoMan]

The difference in OD between SXL and GXL is nominal - perhaps a few percent.  The 6-gauge GXL @ Terminal Supply Co maybe the heaviest gauge cross-linked polyethylene easily available.

Had any dealings with them before? I can't get a price without them wanting an account.

WAYTEK has 6 GA SGX Battery Cable, $55 for 100ft. S&H unknown.

[bd]

Setting up an account is a matter of providing your name, phone and email address.  Rarely, I receive a phone message with specials of the month.  Their site doesn't provide instant gratification, but I have never been dissatisfied with their products or prices, which I suppose is a limited endorsement of sorts since I am somewhat particular and specific in what I want.

[IdahoMan]

Back to the breakers..

Carling
Pros Rocker
MasterVolt

They all look identical, but vary in price. Any of these have a good/bad rep?

[roger97338]

not to be mean or anything but i think a small generator would be a better idea

There have been plenty of times I could have used a quiet modest capacity generator.

Several companies also make generator/welder combos. I bet if you've needed a generator, you've needed a welder at least once, too.

[IdahoMan]

Using the cab or frame for the ground path rather than running dedicated return ground legs should be adequate for your purposes.  But as stated in the prior post (especially if using the chassis as the ground path and high-current additions), the various OE ground jumpers should be upgraded.

• Battery-to-engine (4 gauge is typical, 2 gauge is recommended)
• Battery-to-right frame rail (10 gauge)
• Battery-to-radiator support (10 gauge)
• Engine-to-left frame rail (an optional ground) (10 gauge or 5/16" braided copper strap)
• Cab firewall-to-back of right cylinder head (10 gauge or 5/16" braided copper strap)
• Instrument panel and cluster grounds-to-cab sheetmetal next to the parking brake pedal assembly (various gauges ranging 18 to 16 gauge)

You wouldn't happen to know how much resistance the frame rails have would you? They are steel and not copper but there's more area. (The specific resistance of copper is 10.37, I think steel is around 10+ times that)

[bd]

You wouldn't happen to know how much resistance the frame rails have would you? They are steel and not copper but there's more area. (The specific resistance of copper is 10.37, I think steel is around 10+ times that)

You are way overthinking this.  Resistivity is defined as the actual resistance of a uniform material, times the cross-sectional area of that material, divided by its length.  Its units are ohm-meters.

Steel has ~40 times the resistivity of copper.  In contrast, the resistivity of aluminum isn't quite double that of copper.  So what?  The significant limiting factors to current flow through the cabling are whether wire gauge is properly specified for the current demand and that the area of contact between the metals is adequate.  That, in part, is why high current circuits employ connections with high contact area terminals.  Moderate- and low-current circuits are less demanding (more forgiving) on the terminals used. 

The cross-sectional area of a steel frame is huge in comparison to the cross-section of the copper cabling typically used in vehicles.  So the solution to your concern is selecting cable that will result in no more than about 1.5% voltage loss across the run for continuous current circuits, and 2 - 3% loss across intermittent use circuits.

[IdahoMan]

I think you repeated what I said.

Np. I've got it calculated now.

Thanks much.

[IdahoMan]

CAT temperature and drilling into the frame

350 MCM cable in a 1" wire loom (poly or nylon would match the factory wiring, but I can go for the asbestos if need be) will be my "+" run from the AUX Batt to a junction under the center of the truck. This junction can feed the cab interior behind the seat, and the front of the truck bed. My idea is to shape a wooden platform directly above the center driveshaft bearing (pic1) and place a junction block in that.

How hot does the CAT get and what's the rule about running wiring (in loom) within a an inch or two of it? 
I don't know if I can run a 1" loom alongside the factory wiring loom, there may not be room. Factory loom is on the top of the outside of the left frame rail above the gas tank.

I don't like to drill, and I don't want to compromise the frame in any way. Any rules/pointer for making small holes in the frame for mounting?
For the wire runs going from the center junction to the cab corner hole under the cab I made some "L" shaped pieces out of sheet-metal and stuck them on with 3M mounting tape, the loom clamp attaches to these (pic2).

Pic3 is CAT.

[bd]

350 MCM cable in a 1" wire loom (poly or nylon would match the factory wiring, but I can go for the asbestos if need be) will be my "+" run from the AUX Batt to a junction under the center of the truck

350,000 cmils is between 4/0 and 5/0 cable.  Even welding cable that size will likely be fairly stiff and a challenge to route.  What's your criteria for specifying cable that heavy?  Junction block studs for cable that heavy will need to be at least 1/2" diameter.

How hot does the CAT get and what's the rule about running wiring (in loom) within a an inch or two of it? 
I don't know if I can run a 1" loom alongside the factory wiring loom, there may not be room. Factory loom is on the top of the outside of the left frame rail above the gas tank.

±1,200° F at full operating temperature...
Allow plenty of space for air circulation between a catalytic converter and any electrical power cable, preferably install a heat shield between them.  Arbitrarily, allow >12" between the cat and cable loomed in reflective double wall fiberglass.  Run the cable outside the frame to insulate from exhaust heat where necessary, if possible, but near the top of the frame rail to help protect from road hazards. 

I don't like to drill, and I don't want to compromise the frame in any way. Any rules/pointer for making small holes in the frame for mounting?
For the wire runs going from the center junction to the cab corner hole under the cab I made some "L" shaped pieces out of sheet-metal and stuck them on with 3M mounting tape, the loom clamp attaches to these (pic2).

You can drill the frame face to mount 1/4" Adelle clamps or share the existing holes used to secure the factory loom.  Do not drill the frame flanges.

[IdahoMan]

350,000 cmils is between 4/0 and 5/0 cable.  Even welding cable that size will likely be fairly stiff and a challenge to route.  What's your criteria for specifying cable that heavy?  Junction block studs for cable that heavy will need to be at least 1/2" diameter.

350 kcmil may be excessive. A 1-1.5KW inverter and three 50A DC accesory sockets attached to the end of the main artery (AUX to Junction, 15ft). The heaviest thing I imagine having to use briefly would be a 1KW micowave. 4/0awg or 250kcmil should be fine, better safe than sorry. Surge current needs to be considered too.

Run the cable outside the frame to insulate from exhaust heat where necessary, if possible, but near the top of the frame rail to help protect from road hazards..

..or share the existing holes used to secure the factory loom.

That would be ideal, if there's room.

Thanks.

[bd]

The following discussion isn't intended to invalidate anything that you have already accomplished, rather help you engineer a design that is both high performance and cost effective.  Using cable as heavy as you are proposing (250 - 350 MCM), the surge current in a low voltage environment is immaterial due to its short duration, measured in milliseconds.  The cable can easily dissipate the negligible amount of virtually instantaneous flash heating. 

A 1,500-watt inverter will draw a maximum of ~110 amps for only a couple of minutes before tripping its internal breaker.  It will deliver 1,000 watts for considerably longer at ~75 amps of draw.  Similarly, the 50-amp accessory sockets, individually protected, will deliver 100% (50 amps apiece) of their individual circuit protection, momentarily, before tripping, versus ~80% (40 amps apiece) continuously, without tripping.  That equates to 150 amps of momentary current flow, versus ~120 amps of continuous current flow.  So, three 50-amp sockets, plus the 1.5 kW inverter, collectively operating at maximum draw would be ~260 amps of current flowing through the supply cable lasting for a maximum of under two minutes, versus a continuous current flow of up to ~195 amps.  Of course, voltage loss across the supply cable generates heat in the cable, which is the major concern.  And, the amount of heat generated is dependent on the cross-sectional area of the cable.

Now, realistically, how much total combined current do you actually anticipate drawing at any given time through the supply cable?  A constant 195 amps?  What is the likelihood that you will be supplying maximum current through all four appliances at the same time?  For how long?  Next, how much voltage loss across the supply cable is tolerable to the appliances you will be powering?  Bear in mind that a starter cable while cranking an engine, commonly consumes 3%, but can consume as much as 5% of the supply voltage and yet the starter still functions.  Use these two criteria along with the length of the cable run to arrive at a workable specification for supply cable cross-sectional area.  I'll leave it to you to do the math and post the outcome, assuming you haven't already pondered this exact scenario.

Edit:  corrected arithmetic and restated for clarity