Electrical Wiring: Amps vs Wire Gauge

Discussion in 'Hacks' started by dholaday, Nov 8, 2012.

  1. Woody2627

    Woody2627 Skinny Decaf Latte Thanks

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    Well there ya go, learn something new every day. Bottlenecks? Nobody taught me that at tech when I did my electronics training, but that was 40 years ago, might be a new thing. :cool:
    #21
  2. rmhrc628

    rmhrc628 Long timer

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    Thankyou so much

    I was going to run 14 gauge as I have some lights to hook up.

    Your response was awesome.

    Any suggested wiring from a reputable wiring company ? What about heat shrink material ?
    #22
  3. Unstable Rider

    Unstable Rider Moto Fotografist

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    I find this wiring-sleeve weave stuff most handy. Or I call it boat rigger's weave, or Chinese finger-trap weave :evil

    I get it in various sizes and colors from these guys. It's affordable in bulk, and a roll lasts me a long time, they will indeed sell to the public. Makes the project look nice when it's done too.

    Like in the picture, when combined with a bit of heat shrink tubing, it makes a custom wire run look better than factory.

    Ps: Harbor Frieght sells a great heat gun for like $8 bucks.

    www.cablemarkers.com

    [​IMG]
    #23
  4. dholaday

    dholaday Been here awhile

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    It's been said earlier in this thread but it's worth repeating: When choosing a wire gauge consider not just the amps a device will pull, but also the TOTAL length of the run - i.e., from battery to device to ground.

    On a sidecar rig, that could be 15 feet or more.

    Note also that the chart DRONE posted [and that was included in my link in first post] is for American Wire Gauge - AWG is a little more robust than automotive SAE gauge wire.

    You might also choose to use marine wire - it comes in AWG and the strands are tinned to better resist corrosion; again, a little more robust than plain copper strands.

    I'm considerably more conservative than DRONE when it comes to wiring - I'll move to one size larger [or maybe even 2 sizes] than recommended just for my peace of mind . The difference in cost is negligible.

    Ask The Google for marine wire - there are LOTS of sources, including Amazon :-)

    One of the things I still haven't figured out is what adding a bunch of additional stuff to the bikes OEM wiring does, if anything.

    Thanks,
    Duncan
    #24
  5. Abenteuerfahrer

    Abenteuerfahrer Deaf on Wheels

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    Hi Duncan..

    Rest assured that your rigs accessories are totally isolated from the BMW Canbus system...all accessories are ALL wired directly from the battery protected by a Centech fuse box. Nothing is borrowed from the the bikes system...!

    The only OEM plug that is still dedicated to the Canbus system is the BMW plug underneath your seat...which is never used...anything over 5 amps..Canbus will trigger a shut off. Connections to the taillight for Sidecar stop lights and/or running lights are send there via a relay that is again powered straight from the battery.

    All of these are powered straight from the battery..

    GPS'es
    Dashboard-BMW plug for heated jackets(bike and sidecar
    Flood Lights on Bike and sidecar
    Sidecar Tilt actuator

    One Caveat tho:

    Everything can be run: Heated vests in sidecar and bike; GPS; full flood lights on both appendages and whatever suits your fancy while motoring at 3000-4000+ rpm...but once going through Town and slowing down...it is recommended that the flood lights/hi-beam be dimmed and/or you extinguish your heated vest for SHMBO:D.

    In my travels I have never needed a higher battery or multi batteries. The Odyssey 535 served me very well with smart use of power needed.

    cheers....
    #25
  6. dholaday

    dholaday Been here awhile

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    Hi Elmer:
    Good to hear from you.

    Thanks for the wiring information. It's very helpful.

    I got myself into a re-wiring project slowly:
    - First, I wanted to move the Tilt control switch from the right side of the bike to the left so it would be easier for me to operate while underway.
    - Then 2d, to move the car light switch from the car to the bike.
    - Then 3d I thought it might be nice to replace the IPF driving lights on the car - and maybe the bike - with LEDs to reduce demands on the charging system [BTW, the Odyssey has performed well for me too.]
    - That led to thinking about replacing the Centec with a PDM60.
    - And updating the wiring connections to be more like what Jay is doing now to bring wires into and out of the car.
    - And . . .

    Mission Creep strikes again -

    Please say Hi to the beautiful Sharon for me

    Duncan
    #26
  7. XL-erate

    XL-erate Been here awhile

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    Regarding the AWG wire and SAE wire, AWG American Wire Gauge wire is specifically designed and made for Residential, Commercial and Industrial applications. SAE wire is for vehicles. Marine Grade will have other specifications added for further safety. AWG is much thicker strands made of different copper alloys than SAE. AWG has fewer and heavier gauge strands in a given wire gauge size than SAE does. Conversely the SAE has more strands of a lighter gauge in the same 'Gauge' rating.

    The AWG wire is intended for the express purpose of being used in permanent, static non-moving applications, often run inside conduit and securely fixed to prevent any movement at all. The alloy in AWG is not designed to flex, is less malleable. When run in conduit the conduit is placed with whatever bends in it, then the wire is pushed or pulled through, making those turns and bends, one time. That's it for its lifetime, never intended to be moved [flexed] again.

    AWG wire also has several classifications such as TW, THW, TWN, THWN, THHN etc. which are specifications for a particular purpose and use. This is worth investigating to know what type of wire you're actually dealing with. These can relate to the conductor's alloy and the plastic sheathing layers on outside plus temperature. The plastic sheathing coating on AWG wire isn't friendly to light or ozone and hardens much more quickly than SAE wire which remains far more flexible for a much longer time.

    SAE wire with fine, thin strands is designed to be used in applications with movement, vibration and possibly temperature changes. The fine soft strands are more forgiving of flexing and the alloy is such to withstand flexing without work-hardening much moreso than the AWG stuff. Vehicle use also requires more hand manipulations of the SAE wire during initial installation and it's often moved and flexed several more times in its life in order to facilitate troubleshooting and repairs so it's simply made to be more flexible throughout its life.

    Similar example is wire used in extension cords. Cut one open and you find super-fine strands, lots of them. That's because extension cords are specifically intended to flex around whatever and wherever without becoming work hardened.

    Also regarding solder, note that there's all kinds of different alloys, some very hard, some very soft, some with specific properites for specialized applications including different fluxes in flux core. Some of these alloys may have a chemical reaction with disimilar metals and cause rapid corrosion and conductor failures.

    Another note: Residential/Commerfcial/Industrial wire tools for AWG wire do NOT work on SAE wire because the extrenal size of a gauge is different. You end up with nicks and cuts in all the outside strands in a conductor if you use the wrong type of stripper.

    The proper wire with the proper solder and flux, or else proper wire with proper connectors and assembly technique, using the right tools make all the difference in the world, especially at 10PM in the dark in the rain in the middle of nowhere.
    #27
  8. XL-erate

    XL-erate Been here awhile

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    Regarding the question of adding in or changing of existing looms on a bike: the advice given in previous threads applies. You need a particular size of wire for a particular amperage over a given distance. There have been few cases where a conductor is too large for the application, due to the nature of electron flow. However the fuse or breaker must be matched to the ampacity of the device or else it offers no protection at all. Amps x Volts = Watts and dividing Watts by Volts tells you the Amps and required fuse/breaker rating.

    This means that if you have an 18 gauge wire going to a marker light as original equipment you don't tap into that, just because it has power to it, to install a pair of 100 Watt Hella lights.

    The same obviously goes for the fuses on a given circuit. They're sized for the length of run and the amperage load of the device, period, nothing else! In many cases I've changed from fuses to commonly available circuit breakers yet with the same amp rating.

    There are 'Mains' circuits in a bike that are heavier gauge than 'Auxiliary' circuits. If there aren't, and they're becoming more of a rarity, MAKE YOUR OWN!

    Where you have existing wiring either in a loom or separately, you need to trace it by hand or by diagram to find out what all is connected, what the source fuse rating is, and the amperage of what you wish to add. In some cases, if you're planning to add a lot of doo-dads [my, how we do love those doo-dads!] it's best to go back to the main power panel or fuse box and identify the main circuit, then add a new dedicated main conductor for all the new stuff.

    You run a new wire of say 12Ga from main panel to dashboard and then you can install inline fuses for all the sub circuits off that along the way. These may be lighter gauge wire than the main, specific to the current draw of the device, but never heavier gauge wire or fuses. The separate fuses or breakers for each new device if properly sized will blow before the whole circuit overheats and causes disaster. The new main wire circuit must be of sufficient gauge to handle the total load of all added devices at once, so note the current draw on this circuit somewhere as you build. There is the straw that broke the camel's back syndrome.

    This way you have an independent circuit that doesn't put any extra loads on existing wiring and it's pretty simple to run one new wire. If possible a new color can save you lots of fiddling or headaches later, always knowing that's the new heavyweight 'Main'.

    Same with the hack: one power source over the side, then sub-fuses at the different devices for microwave, colored TV, DVD player, air conditioner, ice maker and dish washer.

    One thing that causes more problems more often than anything else on vehicle electrical, especially bikes, is POOR GROUNDS! Corrosion is so common with bikes and it wreaks havoc on grounds. All chassis grounds must be to clean bare metal and an anti-corrosive, like dielectric grease or others should be used. Vaseline or chassis grease will do in a pinch. Grounds must also be rated to the current load in a given circuit.

    .
    #28
  9. dholaday

    dholaday Been here awhile

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    XL-erate

    You clearly know a lot about wiring, certainly more than I, and more than enough to confuse me. Especially since we are talking in generalities over time-lagged forum postings.

    But marine-grade wire is tinned AWG, not SAE plain copper. And boats move around a lot, and flex, and are subject to vibration and weather, and seem more like a sidecar rig to me than they do to a house.

    Re fuses - most of the gear I've seen has a fuse with an amperage rating higher than the actual current draw of the attached device. Heated gear is a good example. So is a GPS. And Aux lighting. And Auxiliary power plugs. Seems like the fuse is there to protect the wiring rather than the device.

    I understand that I should not attach a 15-amp device to a 22-gauge wire with a 5-amp fuse. But I don't see anything wrong with attaching a 5-amp device to a 16-gauge wire with a 15-amp fuse.

    Confusing matters further is that my GS runs on a CANBUS and thus has no fuses except for those various owners have put on. I haven't the foggiest idea on how to figure out how BMW has 'fused' the OEM wiring, or what effect tapping relay trigger wires into that wiring might do. But we all still do tap into the OEM wiring for LOTS of things - and the roadside is not littered with burnt out hulks.

    Maybe if we can bring the conversation down to specific applications, rather than generalities, I can become less confused.

    Thanks,
    Duncan
    #29
  10. DRONE

    DRONE Dog Chauffeur

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    If I had learned this somewhere along the way, I certainly didn't retain it in my sieve-like noggin. Just went out to the garage to look at my spools and as far as I can tell EVERYTHING I've been using on my bikes for the past 5 years is AWG! :puke1

    I've never had a wiring related failure on a bike, but maybe I've just been lucky. Anyways, I think I'll head on down to West Marine next week to lay in a stock of SAE or Marine Grade spools and toss the junk I have in the trash. And I might buy a new stripper too!

    Thanks for the schooling, XL! And BTW, I took your advice from earlier in this thread to buy a quality butane powered soldering iron to replace my POS electric one. Haven't tried it out yet, but at least I got it. Guess I better start shopping for some higher quality solder while I'm at it.

    As Davebig likes to say, will it ever end? :lol3
    #30
  11. davebig

    davebig Another Angry Hun !

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    Your the one wondering if it ever ends Ned ! It doesn't
    XL is right of course and marine grade wire is superior to what you have most wire sold over the counter in auto parts or farm stores is crap.
    But the only people still soldering are the airplane wire harness people the rest of us crimp, the problem being too much heat causes a a brittle spot, all high end welders and plasma cutters (lots of heat & amperage) are all crimped.Given that info good crimping pliers are hard to find and it takes a bit of practice, and good ends are hard to find, the welder electric tech endorses digi key.
    He also says simpler is always better avoid high tech drama fuse panels are great, and as XL pointed out grounds are very important need to be clean and well made.
    Duncan that's a really nice bike Elmer did a nice job and in the words of my plumber " if it isn't broke don't fix it".DB
    #31
  12. XL-erate

    XL-erate Been here awhile

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    I hesitated before replying in the first place. My intention is to help others with problems, including attempts at explanations to increase overall understanding of a system or technique etc. The less a person may know on a given subject the more I'll try to explain. Sorry if it gets wordy when I get carried away. I also add info so someone doing archive search may be helped.

    Of the wire types commonly available there are two basic types. One type is Residential, Commercial and industrial wire, which I was referring to as 'AWG', after the National Electrical Code 'American Wire Gauge'. AWG may be listed as various descriptions from TW, THHN etc. to futher clarify what I was referring to. It's the wire normally found at local hardware stores labeled TW [most common], TWN, THW and sometimes THHN which has additional clear nylon outside sheathing.

    AWG isn't the exact nomenclature of wire types but is common, somewhat like a sidecar is called a hack or a tub. I know of well over 100 particular types of electrical wire with specific nomenclature describing alloy, coating, sheathing, protective, usage and size categories. There's probably three or four times that many out there but no point in further sub-categories for sake of brevity and simplicity. AWG shouldn't be used on vehicles.

    Generally the other common type is automotive wire, referred to here as 'SAE', after Society of Automotive Engineers, which doesn't use the descriptions TW, TWN, THW etc. Automotive 'SAE' wire contains more strands of finer thickness in a particular gauge size than 'AWG' wire such that it's more flexible. May also be different alloy than 'AWG' wire and uses different insulation coatings. SAE wire gauge size is not the same as AWG, SAE being smaller overall outside diameter per gauge. That affects the use of strippers and how well they perform without damaging wire. SAE gauge strippers will damage 'AWG' wire conductors and solid wire strippers will damage multi-strand wire.

    One of the stronger automotive types is HDT. GXL isn't as thick insulation but is more flexible. SXL is the common wall thickness of insulation usually found. GPT is the most common automotive retail store type. HDT is a good choice for motorcycles and some marine apps [other than actual Marine grade wire] if kept from extreme heat. In general, Marine wire such as Ancor is a good choice per specification when in doubt. Some but not all Marine wire is tinned. CAN-Bus is sized according to SAEJ1939, yet another type and Metric, has much larger minimum bending radius.

    Fuses are sized to protect the circuit to prevent damage. Attaching a 5-amp device to a 16-gauge wire with a 15-amp fuse will protect the wire circuit but not the device. Also depends on where fuse is located, at source or just before individual device as to what's protected.

    Info on general wire types:
    http://www2.eem.com/Wire_Cable.aspx
    http://www.daburn.com/wire-singleconductor.aspx

    This site incorrectly implies that SAE wire is the same gauge as AWG gauge:
    http://www.awcwire.com/FAQ-Automotive-Wire.aspx

    Automotive types, after SAE Specs:
    http://www.kayjayco.com/wiretables.htm

    http://www.automotivewire.info/automotiveprimarywire.htm

    Excellent Marine info with size warning, shows difference in Mean Circular Mils of SAE and AWG:
    http://www.cncphotoalbum.com/doityourself/wiring/wiring.htm

    Beyond earthly wire:
    http://aerospace-cable.info/types.php

    A common problem with wiring nowadays is foreign mfd. products. Metric and ISO 6722 measures don't match American SAE J1128 or AWG inch/foot, never can. Products sized to one system don't precisely match the other. Both wire and wire tools may be sized metric or 'American', often causing mismatched tools to nick or cut conductors under coatings which weakens wire and lowers conductivity. Added to differences in actual gauge size in wire types it becomes more serious. I prefer Klein tools.

    Another potentially serious problem comes from abrasion caused by loose or incorrect wire ties and clamping devices. Proper tie-wraps or restraints are critical in cycle wiring. Nylon tie-wraps can cut right through many common wire coatings so it's real important to get them very tight to prevent movement and abrasion. I like to wind a couple of wraps of Scotch 33+ or Scotch Temflex 1700 around the wires or bundles before tie-wrapping to further guard against wear and abrasion.

    I spent a lifetime working with various different electrical systems, controls and wiring of all sizes and types so I have more than a passing familiarity with wire, wiring and devices. There are many different working standards governing wire types all with their own specifications and peculiar nomenclature. I stuck with the terms already used in the thread so as not to pour in more confusion. Because I have some experience there I thought I might be able to help, sorry to confuse.
    #32
  13. dholaday

    dholaday Been here awhile

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    I agree that Elmer did a great job, but I need to make a couple of changes to suit my riding style [moving the tilt control and sidecar light switches], and, as Elmer said earlier, the halogen IPF driving lights really put a load on the battery - one that can be fixed by using LEDs [I'm sure that if they had been readily available when Elmer built the rig, he would have used them].

    I've had some corrosion problems with the Centec. There are lots of replacement choices but I decided to give the PDM60 a try. If it doesn't work out you will see it in the flea market.

    Thanks,
    Duncan
    #33
  14. davebig

    davebig Another Angry Hun !

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    I took a look the Lowe PDM 60 site and since I don't have a Canbus bike I'm thinking its not for me, here's something you'd rarely here me say, I'll take a more conservative approach.DB
    I'm not going to post my organized rats nest under the tank.
    [​IMG]
    Fuse box in trunk of sidecar always hot only will handle externals and sidecar stuff.
    [​IMG]
    Optima battery wired to BMW power via 4 awg welding cables, under the tank is a eastern beaver 3 circuit solution with one circuit switched and 2 PIAA harness their associated fuses in relays tied up in semi neat bundles, I hate it but its reliable and simple may take it to welding shop where I hang out during winter and reorganize once more but I don't like the idea of chopping up PIAA harnesses unnecessarily. DB
    #34