Entry Service wire gauge?

[DOUG38S]

What size wire should I use for 100amp service and 225 run to my garage? What size aluminum wire? Is there a handy chart I can use?

[DOUG38S]

I'm thinking 2/2/4 aluminum three wire? Can someone confirm?

[sedat]

Why aluminum? It creates hot spots. Go for copper.

[DOUG38S]

$$$. Three times the cost of AL.

[fj40guy]

Why aluminum? It creates hot spots. Go for copper.

$$$$ :D

Local codes will vary on use of aluminum.

http://www.pec.coop/Documents/ResidentialMeterLoopEnglish.pdf

Note, this is loop service to meet code IN MY AREA (TX). Check with local folks if they have the same requirements.

I went with copper. With aluminum you need to pull power ONCE A YEAR and check all connections. No thanks. Copper and be done with it.

[j-me4runner]

Doug- Talk to Alan (team mt jam), hes an electrician.

[dakuda]

How far of a run?

I just ran 100amps from my house to garage and used #3 copper for the approx. 100ft. run. I had my little brother check with the electrician at work, and I got the copper or free though.

[DOUG38S]

What I am really concerned about is loss of power with that far of a run and having too much voltage drop.

[dakuda]

When I talked to my brother, I told him to ask the electrician what size to use for my specific run. #3 was the answer. I figure if this guy is allowed to wire up Chicago Public Schools and USPS Offices, he might be able to help me.

[TBM Jeep]

I don't have my code book in front of me right now, but off the top of my head i know that you will need to keep the voltage drop under 5% for the 225' feeder. You WILL need to upsize the conductors for that long of a run if you want to have 100 amps of usable current in your garage.

Don't skimp on the wiring, USE COPPER! You are going to have to have a much larger aluminum conductor to carry the same current that a smaller copper cable could carry. At that length you might need something like 2/0 aluminum compared to like #1 copper cable (don't quote me on those sizes).

Aluminum will need to be checked and re-tightened EVERY YEAR, and if you don't and the lugs becomes loose at the main panel or the sub panel and it sparks and a fire starts because of it, and if you cant provide WRITTEN documentation stating that you did religiously check the connections your insurance wont cover it! It's a big pain in the ass and it is honestly not worth the hassle for the minimal cost savings it may provide upfront.

Don't be a cheap ass, use good material (use copper wire). Why would you skimp on something like this that has a potential to cause a fire and burn down your house/garage?

About 10-20 years ago in this area there was a rash of house fires in new homes that were wired with aluminum romex. The aluminum conductors over time (if not properly re-tightened each year) WILL work themselves loose from the outlets/switches, lugs at the electrical panel, on wirenuts, etc... and will lead to fires. I for one will never use romex (doesn't provide enough protection---use conduit), or aluminum conductors in my house! I know better and have seen first hand what improper installations can cause. It's just not worth it to try and save a few bucks.

Tim
Union Electrician
IBEW Local #176

[Chris]

In California ALL new service feeders(commercial and residential) are pulled by the utility companies in AL so it sounds ok for me. Use Nolox paste and check your connections every year or so but if you use a torque wrench and set them to spec it will be fine forever. The Nolox will keep it from arcing if it should come loose. I don't have a code book in front of me so I can't tell you the size but AL is constantly used by DWP and Edison, two of the largest utilities in the country. IT is fine. I agree with not using al romex inside but service feeders are just fine. :rolleyes:

[4xtoy]

What size wire should I use for 100amp service and 225 run to my garage? What size aluminum wire? Is there a handy chart I can use?

Depends, free air, conduit or direct bury? There is nothing wrong with aluminum as long as you use crimp lugs on the terminations. With Free air or direct bury, Aluminum is the best way to go.

On a 225' 100amp 240v service, #3 copper will give you 11 volts drop resulting in a final voltage around 230v or #2 aluminum will give you 14v drop.

We always up the wire size by one size for anything over 100-150 feet. So if you use copper I'd go #2 and #1 for aluminum.

Hope that answers your question. NEC code book will have all your answers but very confusing to read. You can also get a UGLYS Electrical Reference guide if availible were your at.

Never use aluminum for branch circuts NEVER! Service entrance only and only with the use of crimp lugs.

[HalfFastFord]

When I built my shop back in Delaware, I used 2/0 aluminum for a 90 foot 240v run. Worked fine, but it was a lot shorter than your run. If you're that worried about the price of copper, you could probably buy it for about 1/2 price if you have a meth heads running around.

[DOUG38S]

The aluminum is only going to be for the service. It will be buried in conduit. Everything else will be the reg 12/2 copper wire that you get in bundles for lights. switches.

[fj40guy]

Doug,

I missed the 225' run length. Doh! I was thinking of the entry (meter loop) drop connections.

For 225' feet of buried cable, with aluminum it would be 2/0 sizing. Neutral can be run as 1/0 aluminum. Once again check your local code (I'd hate to use #1 for neutral, only to have it not signed off by an inspector who wanted 1/0 used).

How straight is the run? Pulling 225' of cable is a pain. 2/0 Aluminum is a real pain in the the rear. I'd almost be tempting to run 3" conduit just to get the cable out to the shop (do you have a cable puller?).

2/2/4 sizing you mentioned would be fine in copper THHN wire. About $6/ft for the three wires in thhn. Advantage would be easier to pull in a small conduit, but at almost $1200, I'd go with the aluminum.

[Bmf24]

The aluminum is only going to be for the service. It will be buried in conduit. Everything else will be the reg 12/2 copper wire that you get in bundles for lights. switches.

i came up with 2/0 alum also. it seemed like it was overkill when reading it on here but its what the calculations are comming out as. must be the long distance.

[TBM Jeep]

If you have access to one of the hydraulic crimp tools definately use it. They are way too expensive to buy for a single use though. You might be able to rent one from an electrical supply shop, or a rental place, or maybe even a local electrical contractor. That would alleviate the loosening problems of the aluminum wire.

I know i'm a little biased towards using the copper wire because that's pretty much all we use up here. But IMO it's not worth the added hassle using the aluminum wire....having to re-tighten the connections frequently, need to upsize the conductors to carry the same current as a smaller sized cu conductor, and in the same time having to upsize the conduit to hold that bigger wire.

I'm assuming you are using pvc instead of rigid conduit correct? Just a word of advice for the conduit run out to your garage, for the 90's use the prebent rigid 90's. With that large of aluminum cable being pulled in the conduit you will have to use a 3/8" to 1/2" rope to pull it in. The rope can and will dig into the pvc 90's and get stuck and you'll have to dig it up to fix it. The rigid 90's are more expensive but you wont have any problems pulling the cables in. The price difference for the pvc vs rigid 90's are probably 2-3x as much, but you should only need 2 or 3 of them.

I've never price checked the aluminum vs copper wiring. Didn't realize it's that much of a price difference. So if you're looking to save some money and you could manage to get the ends crimped i'd go that route. Also make sure to use lots of pulling lubricant for the long cable pull (either yellow-77 or the clear pulling lube).

Tim

[uglyscout]

I'm assuming you are using pvc instead of rigid conduit correct? Just a word of advice for the conduit run out to your garage, for the 90's use the prebent rigid 90's. With that large of aluminum cable being pulled in the conduit you will have to use a 3/8" to 1/2" rope to pull it in. The rope can and will dig into the pvc 90's and get stuck and you'll have to dig it up to fix it. The rigid 90's are more expensive but you wont have any problems pulling the cables in. The price difference for the pvc vs rigid 90's are probably 2-3x as much, but you should only need 2 or 3 of them.


I know that in my area they will not allow you to use PVC elbows - for just the reason explained above.

My buddy had to big them all up and replace them before the cable could be pulled....

[DOUG38S]

I used 2" conduit. I guess its the rigid stuff. It is gray in color. I'm checking on code stuff today through a round about source. Pull is straight and I ran 3/8th rope. I didnt think about any lube. Makes sense since you are putting it in a big dark hole.:D

Can someone explain the needing to tighten everything up at the service box every year? Once its in and tightened nothing is going to move it, right? The rest of the building will be the regular 12/2 copper wiring for lights/switches/outlets.

[fj40guy]

Can someone explain the needing to tighten everything up at the service box every year? Once its in and tightened nothing is going to move it, right? The rest of the building will be the regular 12/2 copper wiring for lights/switches/outlets.


Have fun with the pulling! (My hands ache just thinking about it... )

On the wiring... OLDER ALUMINUM was subject to creep. Everyone remembers that stuff and the problems it gave as you would tighten in down, but it would "cold flow" away from the clamp leaving a loose connection. Loose connection + oxidation meant heat, which resulted in fires.

You can use 14 ga wire on your 15A light circuits. I'd go with 12 ga on outlets as you mentioned (20Amp circuits and outlets). Have you already installed your panel (I still prefer Square D QO line)

[DOUG38S]

Yeha already installed the panel.

[Mechanos]

I used 2" conduit. I guess its the rigid stuff. It is gray in color...

"Gray in color" tells me it's plastic (specifically, PVC). "Rigid" is a type of thick-walled metal conduit. EMT is the thin-walled metal conduit.

[bigdreamin]

I for one will never use romex (doesn't provide enough protection---use conduit), or aluminum conductors in my house! I know better and have seen first hand what improper installations can cause. It's just not worth it to try and save a few bucks.

So what do you run? EMT and THHN? I can see not using Al romex, I believe it has even been outlawed, but not using romex all together? Seems like money is not the issue it would be the labor involved. Even flexible seems like a pain in the ass.

[TBM Jeep]

So what do you run? EMT and THHN? I can see not using Al romex, I believe it has even been outlawed, but not using romex all together? Seems like money is not the issue it would be the labor involved. Even flexible seems like a pain in the ass.

Yes, most if not all of the bigger counties in northern illinois use emt and thhn wiring as opposed to romex. You can still get away with using romex in some individual cities here and there, just depends on the AHJ. And i'd be willing to bet that around most major cities in the nation that emt is the norm.

I just feel that emt is safer, easier to make changes down the road (re-pull an extra circuit, or rewire something), and just flat out more professional way to do it. Anyone can drill some holes in studs and run some extension cords in their walls and call it done. Emt installations take much more thought, skill, prep work and IMO is a better electrical installation. Just the thought of someone going to hang a picture or something on the wall and driving a wood screw thru the stud and hitting the romex and it shorts out starts a fire just doesn't sound right to me.

FMT (flexible metallic conduit--"flex") shouldnt really be used for the whole installation. It's used more for fishing in an outlet in a wall where you want more protection for the conductors over romex. It has its place, but definately not the cheapest solution for an entire house installation.

An emt installation isn't that much more cost wise when you really think about it. Romex is much more expensive per foot than regular thhn wiring. There is a bit more labor involved, but for me that's not a bad thing, gives us electricians more work! ;) In some of the track homes around here i've heard that the cost difference between a house done in rope or in conduit is only like $500-$1000 for the whole house. Seems worth it for a much safer and more professional looking installation.

Tim

[TBM Jeep]

Oh, and another thing. Since you have 2" schedule 40 pvc conduit you will have a bitch of a pull with the 2/0 aluminum cables. The 2/0 cables are a little less than half an inch in diameter (0.418") plus the outer insulation thickness, and the wire fill for the 2" pvc is a max of 3 to 5 2/0's (depending on the type of insulation the cables have), so you will just barely squeak by with the three 2/0's and a #4 ground wire, but it will be hard. You definitely need to make the head of the cables as small as you can without making it too weak.

This is kind of hard to explain in words but i'll try....

The cables are all made up of multiple strands. Strip back about 20" of insulation on each of the cables to be pulled in the conduit. Take the exposed piece of one of the cables and twist back 3 of the individual strands all the way back to the insulation. Do this again so you have 2 sets of 3 unwrapped strands wound back to the insulation. Now bend each set back to expose the inner 8-10 strands. Cut the inner strands off as close to the start of the insulation as you can. You then bend back those 2 sets of 3 strands so they are all facing forward again. Now take that 3/8" rope and put an eye splice in it and take 1 set of the 3 strands and thread it through the eye, bend it back on itself (so it does NOT go past the insulation) and then take the second set of 3 strands and thread it through the eye in the opposite direction you put the first set through and bend it back and even it up and tighten it down. When you cut out the inner strands you made room to bend those 2 sets of 3 strands back upon themselves WITHOUT increasing the outer diameter of the cable itself. Now do this for each of the other cables and tighten down the wires that wrap around the eye of the rope and tape it up real good. Try to make the head as smooth as possible. If the head is a little bumpy take a small old rag and wrap it around the strands of wire to fill in the low areas and then tape it up real good.

This will enable you to pull in that big cable in the tight conduit hopefully without it binding too much and hopefully leaving your balls intact. Go buy about a half gallon sized container of Ideal Yellow-77 pulling lube (it looks like and has the consistency of butter). Use this liberally, even take a couple handfulls and shove it in the pipe before you even start to pull the cable in to hopefully lube the head real good. Have 1-2 guys pull the rope at the sub panel, one guy feeding and soaping the head/cables at the main panel (BE CAREFULL TO NOT TOUCH THE MAIN LIVE BUS--put cardboard over it), and one or 2 other guys to feed the long loop of cables to the guy feeding the cables into the conduit.

And if you think your 2/0's are bad the biggest cables i've pulled in so far were 1000 KCM cables, they're about 1.75-2" in diameter EACH! We had like 20 guys involved with that pull alone, used 2 tuggers in tandem, 2 guys working the tuggers, 2 guys manhandling each spool of cable, 2-3 guys soaping, and the rest feeding in the cables.

Good luck,
Tim

[u2slow]

I see and use aluminum for feeders all over the place. Its the norm up here. Its even crawling back for stove and dryer circuits in homes. All the utilities use it. Even the busswork in the substations where its replacing the old copper.

Insurance companies gawk over fuses (instead of breakers :rolleyes:), knob&tube wiring, and any panels under 100A nowadays. Aluminum is basically off the radar.

Even though its in a sealed conduit, its underground - so still considered a wet location. I'm not a fan of downsizing neutrals.

[fj40guy]

Even though its in a sealed conduit, its underground - so still considered a wet location. I'm not a fan of downsizing neutrals.

With copper prices, I'm surprised we don't see more aluminum down here.

My shop is all copper. Only issue I had was with a SQUARE-D QO breaker. I got a fawking china clone (bogus breaker) off eBay. Didn't notice it until I started installing the breakers and realized "that one doesn't fit right... odd doesn't look like the rest". Hammer and toss into the trash can was the solution. :D (ebay special).

On Downsizing neutrals... If most loads are 220V, and few outlets, nothing wrong with downsizing neutral. Typical of a shop with welders, compressor, etc. On my 200 Amp panel, it was almost 75% of the load being 220V, 25% being 110V. So downsized neutral isn't an issue. If a dwelling with gas appliances (stove, dryer) then the load balance will show almost everything on 110V, so neutral should be same as the legs.

[bigdreamin]

Yes, most if not all of the bigger counties in northern illinois use emt and thhn wiring as opposed to romex. You can still get away with using romex in some individual cities here and there, just depends on the AHJ. And i'd be willing to bet that around most major cities in the nation that emt is the norm.

I just feel that emt is safer, easier to make changes down the road (re-pull an extra circuit, or rewire something), and just flat out more professional way to do it. Anyone can drill some holes in studs and run some extension cords in their walls and call it done. Emt installations take much more thought, skill, prep work and IMO is a better electrical installation. Just the thought of someone going to hang a picture or something on the wall and driving a wood screw thru the stud and hitting the romex and it shorts out starts a fire just doesn't sound right to me.

FMT (flexible metallic conduit--"flex") shouldnt really be used for the whole installation. It's used more for fishing in an outlet in a wall where you want more protection for the conductors over romex. It has its place, but definately not the cheapest solution for an entire house installation.

An emt installation isn't that much more cost wise when you really think about it. Romex is much more expensive per foot than regular thhn wiring. There is a bit more labor involved, but for me that's not a bad thing, gives us electricians more work! ;) In some of the track homes around here i've heard that the cost difference between a house done in rope or in conduit is only like $500-$1000 for the whole house. Seems worth it for a much safer and more professional looking installation.

Tim

I can see the advantage in pulling an extra circuit but how in tech hell do you get a piece of 10' rigid between wall stud 16" on center? As for screws if you use a 3 wood screw to hang a picture maybe home ownership isn't for you, just a thought.

Edit: as for cost you can get 1000' of 14/2 for $160 and 1000' for $260 which would be more than plenty to do a house (minus the few 14/3 's need for travelers and whatnot) Seems like you'd have much more than that in just buying the rigid and fittings. Not trying to argue for romex here, just curious I have never hear of using rigid and thhn inside a a stud framed wall before.

[u2slow]

On Downsizing neutrals... If most loads are 220V, and few outlets, nothing wrong with downsizing neutral. Typical of a shop with welders, compressor, etc. On my 200 Amp panel, it was almost 75% of the load being 220V, 25% being 110V. So downsized neutral isn't an issue.

I follow the logic and Code does allow for it. Why I'm not a fan of the practice is the possible future change of use for the building (perhaps an illegal suite) and the 120/240V load bias changes.

*shrug*. I bury cable for these jobs 99% of the time. No opportunity to downsize the neutral. :D

[TBM Jeep]

I can see the advantage in pulling an extra circuit but how in tech hell do you get a piece of 10' rigid between wall stud 16" on center? As for screws if you use a 3 wood screw to hang a picture maybe home ownership isn't for you, just a thought.

Edit: as for cost you can get 1000' of 14/2 for $160 and 1000' for $260 which would be more than plenty to do a house (minus the few 14/3 's need for travelers and whatnot) Seems like you'd have much more than that in just buying the rigid and fittings. Not trying to argue for romex here, just curious I have never hear of using rigid and thhn inside a a stud framed wall before.

You don't run rigid conduit in walls in a house, you use emt. The emt is only like 1/16" or less thick, rigid is like 1/8" thick. You just drill the holes in the studs so the outer edge is like 1/4" to 3/8" or so back from the face of the studs and the emt bends a bit and you work it in. It's a piece of cake.

As for the price differences i was just recalling what i heard from someone a few years back. The price difference between romex & conduit may be more now, but it cant be that much. You can rope a house in about 30 or so hours. You can rough a house in about 40 or so hours. Service installation and trim installations are identical.

And i've drilled a 3" wood screw in a wall before (in the garage) to hang some shelving & such. :D But i knew my house was piped so it wasnt a worry hitting any romex. So about 10 hours at XX per hour doesnt add up to too much extra, materials are probably about the same i'd imagine.

I'm not trying to say romex is shit and pipe is king. More like romex is butt steak and conduit is porterhouse. ;) Alot of times it falls down to price with pretty much everything else in life, right? I've just always done conduit in the jobs i've been on, so i dont see a reason to do it otherwise.

Tim