Is There Such a Thing as Using Wire That Is *Too* Thick?

[Anonymous]

I was just going over some wiring instructions concerning gauge, and I starting thinking about wiring in general. Of course, using wiring that is too thin causes current and safety problems. But, is there ever any issues when you use wire that is obviously way too large a gauge than is needed? Does resistance become a problem?

Jim

[SteelMonsters]

Thicker wire costs more.

Running bus wires for DCC usually should be thicker to protect the system and locos against shorts where thin wires might not shut the power off properly.

There is a point where thick wire simply takes up too much space. (think a 0 gauge bus of 50 wires) For most wiring, you don't have any use for wire a size or two larger than needed.

To answer your question, too thick is not much of a problem at all, but not budget friendly.

[Anonymous]

Yes, too think means to much power degrigation and signal loss (if using DCC).

Edit: err meant power, not resistance.

[Anonymous]

I'm not sure about DCC signal loss, but if my memory from college is correct, the thicker the wire, the less the resistance. This is why smaller wire heats up.

[Anonymous]

Just out of curiosity, I googled "wire resistance" and found this:

Wire Gauge Resistance per foot
4 .000292
6 .000465
8 .000739
10 .00118
12 .00187
14 .00297
16 .00473
18 .00751
20 .0119
22 .0190
24 .0302
26 .0480

[Anonymous]

As with any material, the wire should be correctly matched to the requirement. While with copper wire, the resistance dminishes as the diameter increases (per dkelly's post above), not only cost but ease of working suggest that you are better off not doing "overkill" on your wire gauge. Crimping and soldering are harder with the larger diameters, larger and heavier wire management hardware is needed, etc. I use 18-gauge stranded wire for the main track-power buses on my conventional-DC layout with wire runs up to about 10 feet and have no problems. I use 24-gauge stranded for the track feeders which of course are only a few inches long.

[Anonymous]

rails5: Good point about the larger wire does have some cons to go with the decreased resistance lol. I guess a 1 foot diameter copper "wire" would get expensive and crimping it would be a little difficult!

I am curious about the above post that mentioned larger wire causes signal problems in DCC. Anyone else have that problem?

[cmrproducts]

The larger wire reduces resistance and allows the DCC signal to get through to the Decoder. As resistance increases the DCC signal will be reduced and eventually will be lost in the noise (that is present on all the wires and rail). Then you will complain that my engine seems slow in responding, when infact it is all the noise on the rails causing the reduced DCC signal to get lost.

Use #12 stranded houe wire and rail drops every 3 feet. You will never have a problem. Anything less and you will never know if it is a problem with the DCC system or excessive resistance.

Your choice!

BOB H Clarion, PA

[Anonymous]

Bob H.

Thanks for the info! Makes sense to me. And like you inferred, it is a balancing act between resistance and signal loss, but thankfully, someone else has done the research already!

Dave

[Anonymous]

Axtually Bob, signal degrigation comes from wavelength distortion and overlapping caused by to low a resistance (as caused by larger diameter wire) and to high a resistance (caused by to small a gauge), this is why phone lines use very tiny gauge wire to prevent any overlapping and degrigation loss of voice waves. Computer CAT cables use a slightlyy larger diameter wire to compensate for the additional power going through the line as well. Proper Resistance Balance actually helps Digital signals stay in frequency.

people have done the work, you're good with 18-22 guage feeders and a 14-16 busline. anything larger than probably 10 gauge and smaller than 30 gauge may cause problems (course i doubt you'll use anything over 24 for the layout as fires could occur).

[Anonymous]

I've used the following numbers for wire gauge and maximum current limits for many years. I've never had a wire overload and burn or melt the insulation. Select your wire to match the application -- don't waste money putting in too heavy a wire, but select a realistic size to match the application. If you plan to increase the usage at some time in the future, upgrade the size now and you'll have it already done..
Electrical Load Current Limits
AWG amps
6 101
7 89
8 73
9 64
10 55
11 47
12 41
13 35
14 32
15 28
16 22
17 19
18 16
19 14
20 11
21 9
22 7
23 4.7
24 3.5
25 2.7
26 2.2
27 1.7
28 1.4

[lonewoof]

SteamerFan: I would like to see the reference where anybody claims that LARGER diameter wire EVER causes signal degradation. Is that published somewhere?

[rrinker]

I think you'll find that any such degredation is frequency related, any calculations involing AC transmission have a frequency component. Now, 100mb ethernet has a WAY higher signal frequency than DCC.

That said, there's WAY more distortion to the DCC signal caused by the fact that the track is a HUGE perfectly parallel (well, MY track is perfect, isn't yours? [:D]) conductor, and as such is going to cause far more inductive and capacitive distortion than using 00 bus wire. This is also why some users have reported better results by slightly twisting the bus wires for long runs rather than running the bus wires perfectly parallel.

--Randy

[cmrproducts]

Yes the signal will degrade with distance using an AC type of signal (Inductive reactance and Capacitive Reactance thing) but with our small layouts this is usually not a problem.

On my layout I twisted all my wires (as in CAT 5 cable), as I was not planning on using Signal Detection. If you are going to use block detection then separate the wires. But now you run into the Inductive/Capacitive reactance thing. Yes it is a balancing act.

Using #12 stranded wire is about the best compromise when making long runs of wire (50ft). And I have went to #8 stranded for some of my very long runs.

My layout is set up in a 25’ x 75’ basement and I have over 2600 feet of track. During some of our big OPTUDs (OP Till U Drop) I have had 40 people on the layout. I am using Digitrax Radio system and am powering this layout with ONE 8amp command station and NO boosters. We are also running about 20 radios

What I have tried to do is pu***he limits of the Digitrax system. So far the only limitation is the BLI sound units with the current in rush problem. I am working on this problem.

So I think I have run into just about every problem there is except the signal blocks problems.

As a side note with the many peninsulas and having run 120 volt outlets for tool use I shielded all of the 120v ac wiring using BX cable. I wanted to eliminate any AC hum from getting into the Loconet or the track via the buss wires. I am trying to keep the noise on the layout/Loconet as low as possible so there is not signal degradation.

And so far it seems to be working. I have helped other Clubs and home layout modelers with their systems that were not able to run any trains without the system crashing. Once they changed the wiring over to #12 stranded the problems suddenly went away. I also recommend that you put wire drops from every piece of track (and I solder all wires at the track joints) and all three ends of a turnout, no exceptions.

So far it must be right as the layout runs anytime I fire it up. Although this is a very young layout only 5 years old.

BOB H Clarion, PA

[leighant]

If the wire is too thick, can't the electricity get lost inside such a big chunk of wire?

[Anonymous]

Naw, the lost electrons just go with the flow and follow the current.

[Bikerdad]

There's one more aspect, regarding the "heavier gauge may be wasting money." Sure, if you go out and buy it just for this project.

What if you've just finished wiring up your train room with all new lights, outlets galore, ceiling fan, etc, and you have a couple hundred feet of 12g left over? Should you go out and buy 14 or 16 or whatever for you main bus, or just use what you have?

hmmmm, spend money, or use money already spent...