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View Full Version : Gauge: 10 vs. 12


Mike M
01-07-2008, 06:33 AM
Most arguments for transformers with taps above 15 include the benefits of longer runs. However, what about typical runs that aren't so long, but simply using the higher taps to keep wire gauge smaller?

I ran some numbers, and it appears the extra cost of a multap transformer above 15 is pretty close to the wire savings on medium sized jobs (couple runs above 100, etc.).

So for the sake of argument, let's say it all breaks even between trans and wire costs. Well, the labor saved would be significant, since pulling wire from a 12 gauge spool and placing it in the trench would be much easier than the 10 gauge.

Seems to make sense, just pay attention to amp load capacity on the wire.

steveparrott
01-07-2008, 07:32 AM
Don't forget energy conservation with #10/2.

Pro-Scapes
01-07-2008, 07:42 AM
So for the sake of argument, let's say it all breaks even between trans and wire costs. Well, the labor saved would be significant, since pulling wire from a 12 gauge spool and placing it in the trench would be much easier than the 10 gauge.

Seems to make sense, just pay attention to amp load capacity on the wire.


Your over thinking this again. If your sales point is high effeciency then use the 10ga. Its a sales point but you need to charge accordingly.

There really is VERY little difference in burying a 12ga and 10ga. Keep expansion in mind when running 12ga tho. If your loading like 150w on it and see a place you could upsell a few lights you may wanna run the 10.

JoeyD
01-07-2008, 10:29 AM
This comes down to preference. You can do just as good of a job using 12ga as 10ga. Your wire costs are cheaper w/ 12ga, it is also lighter and easier to work with. Your max wattage is 192w or 16amps on a 12ga cable vs 288w and 24amps on 10ga so you can pile a few more ligths on the 10ga which is the only real beenfit in my opinion. I think you should use 12ga as your primary cable but have a spool of 10ga for those special situations. But again it is preference, some guys live and die by bigger wire.

Pro-Scapes
01-07-2008, 02:56 PM
both wires have their time and place. use the apropriate cable in the correct situation.

Using hubs its not hard to put 192w on a line in a hurry if your uplighting tall trees.

The cost savings of 12ga fades QUICKLY when you have to run an aditional line not to mention the added cost of doing simple add ons in the future when your wire is close to max.

INTEGRA Bespoke Lighting
01-07-2008, 03:10 PM
Just a thought... What if we took all of the energy and time we spend worrying about "cost savings" and "efficiencies" and applied that instead to marketing, design and sales? I mean really... on a large sophisticated lighting system, who is going to notice the difference between using 300m of 12/2 or 250m of 10/2 or 400m of 12/2 (or whatever, its a hypothetical so dont analyse it to death). Is everyone out there really being this worried over the incremental cost of a few meters of wire?

Something to ponder....

Pro-Scapes
01-07-2008, 04:16 PM
Just a thought... What if we took all of the energy and time we spend worrying about "cost savings" and "efficiencies" and applied that instead to marketing, design and sales? I mean really... on a large sophisticated lighting system, who is going to notice the difference between using 300m of 12/2 or 250m of 10/2 or 400m of 12/2 (or whatever, its a hypothetical so dont analyse it to death). Is everyone out there really being this worried over the incremental cost of a few meters of wire?

Something to ponder....

No because on larger projects I use a measuring wheel to estimate my wire usage very quickly and price thoes projects accordingly. This protects me and the homeowner. I dont want to short myself and im one of the few contractors who feels bad if they over charge for something.

Pro-Scapes
01-07-2008, 11:59 PM
back on his post about ripping people off and stuff... I dont mind service work. Sure tracking down someone elses snafus can be crappy work but its also super educating and usually not all that hard if you stop and think a bit.

I would have to say at LEAST 65% of my work comes from servicing others mistakes. I love new installs and clean canvases to paint as much as any of you but as a proffesional and someone who prides myself on service I will take all the service calls.

If the $500 is what you needed to make the repair worth your time and what you needed to make to cover your profit and overhead then thats what you should charge.

Chris J
01-08-2008, 12:16 AM
Sure tracking down someone elses snafus can be crappy work but its also super educating and usually not all that hard if you stop and think a bit.

I would have to say at LEAST 65% of my work comes from servicing others mistakes. I love new installs and clean canvases to paint as much as any of you but as a proffesional and someone who prides myself on service I will take all the service calls.

Chris. If the $500 is what you needed to make the repair worth your time and what you needed to make to cover your profit and overhead then thats what you should charge.

That's the point Billy! It cost the customer $500 to make it worth my time, but it really screws them. How would you feel if I charged you $500 to change a socket? I truly feel bad when I have to do this to someone, but I have to in order to cover myself.

Pro-Scapes
01-08-2008, 12:41 AM
I would think you should of made it a point to sell her a bette system or reinstall hers with new fixtures you can service and warranty for her since joe blow is not around anymore. If she refuses and it uses up 500 dollars of your time then so be it. If you did it just because it grated on your nerve and you took it out on the client then shame on you.

and... for 500 you should not have changed the socket. What you should of done is replaced it with a new fixture and been done with it vs running all around looking for some oddball socket.

Mike M
01-08-2008, 07:26 AM
Holy crap.

I had an appliance repair man come into my kitchen to repair my icemaker. He stops across the floor, apologizes to me, and explains that he doesn't touch anything GE, and explains it's too stressful for him and he just keeps getting callbacks.

I admired him for it, especially when the next guy came and just put a dab of superglue on a plastic gear, and shows me the letter from GE that told him that was the correct procedure. One week later it broke again.

The first guy is a top notch pro in my perception and he gave me an education in outsourcing and some publicly-traded corporations.

Sounds to me like there needs to be LV licensing asap.

ChampionLS
01-08-2008, 10:42 PM
LOL best way to fix a nylon gear is with a soldering iron and a file!

JoeyD
02-07-2008, 03:46 PM
Ok guys check this out. I am anxious to hear some responses here.

http://www.lawnsite.com/showthread.php?t=214975

INTEGRA Bespoke Lighting
02-07-2008, 03:53 PM
I would need to see the quoted code, standard or specification that states this in order to research it more. Please provide us with this info Joey.

Thanks.

JoeyD
02-07-2008, 03:57 PM
I would need to see the quoted code, standard or specification that states this in order to research it more. Please provide us with this info Joey.

Thanks.


I will respond in the Unique forum with the facts once I get them. I am working on it. See my response to you in the Unique Forum.

I am going to try and keep more of my posting in the Unique forum. Not being a jerk just wanting to be more active in my own forum. I still love you guys!! LOL

INTEGRA Bespoke Lighting
02-07-2008, 05:38 PM
According to the CEC Table 12 the maximum allowable ampacity of flexible cord type SPT-1, SPT-2 (which our CSA wire is) is 25A. So no issues that I can see

JoeyD
02-07-2008, 07:05 PM
I have never heard of 12 ga cable ever being good for more than 20amps.

I will be researching it to find out for sure. Seems like it has some merit to it though.

pete scalia
02-07-2008, 08:49 PM
This only makes sense when applied to 120v circuits. With low voltage we use multiple cable runs and distribute the load over those cables. No UL transformer will give you your target voltage by loading all 25 amps on 1 12 gauge cable. Of course we know that exceeds the amp rating of the cable.

Low voltage lighting circuits where made to handle multiple cables all connected to the same 25 amp protected tap. It's a code violation to install more than 1 wire in a 20 amp breaker. Thus single homerun wire on 120 volt circuits are designed to carry the full amperage rating of that circuit (80% rule applies of course per NEC)

Now you can argue that a moron can load all the 25 amps on 1 12 gauge lv cable. So what, he can also make live 120 volt connections while standing in water . My point is you can't control stupidity.

Pro-Scapes
02-07-2008, 08:56 PM
My point is you can't control stupidity.


I nominate this for quote of the year. Well said pete. No subsitute for common sence

ChampionLS
02-08-2008, 12:18 AM
No guys, it's almost right.

As per UL1838, no secondary can exceed 15 volts, 25amps, 300 watts. This info is also on every label on listed power supplies. (also why each circuit is only 300 watts...duh)

25 Amps is equal to a 300 watt transformer at full load. (so basically, a 12/2 wire connected to a 300 watt transformer with 6 50 watt lights on it is an overload.)

It's only wrong on an overloaded condition.

We print this info on our Lamp Module polybags.

Pro-Scapes
02-08-2008, 07:46 AM
[QUOTE=ChampionLS;2140897]
25 Amps is equal to a 300 watt transformer at full load. (so basically, a 12/2 wire connected to a 300 watt transformer with 6 50 watt lights on it is an overload.)

It's only wrong on an overloaded condition.

QUOTE]


Like we said. Ya cant fix stupid. I see this all the time. How about 600w on a 10ga run with the run connected at 1 end to a trans... the other end connected to another trans. I have seen this. No idea how it worked!