Electrical Engineer needed

[Wolfer]

Thought I'd chime in here on the "ground" as you have the wire size pretty much covered. DO NOT SINK A GROUND ROD!!! You will be grounded through the rod at your main panel and if you ground at a separate rod at your detached garage you have created a ground loop. It's laborious to explain why a ground loop is a bad idea but you'd find out during the next electrical storm.

The national electrical code (NEC ) will require a ground rod at every building. If you run a separate ground wire from your main service to your new panel ( no need to ) then you wouldn't bond the ground and neutral.

[TheCelt]

The national electrical code (NEC ) will require a ground rod at every building. If you run a separate ground wire from your main service to your new panel ( no need to ) then you wouldn't bond the ground and neutral.

Yeup, you are correct!! Code has changed some in the last 20-30 years. I'm guessing you meant Neutral and Ground bonded at main panel but not at sub-panel. In effect a ground rod at the detached building just enlarges the ground plane of the existing rod in that case.

[daniel lawecki]

You have to use deoxidation paste on all aluminum wire by the way I wire for a living.

[Lloyd Smale]

you will already have your ground loop with the utility pole in your front yard. All primary voltage poles are ground and have a ground rod. At least they do in our utility. Adding a ground rod at every enterance gives a shorter path to ground if you have a lightning strike. In our untility and going by our electrical standards for the county EVERY entrance to a building that has a panel has to have two ground rods. Tak my yard. I have a great big pole barn right near the house. Its metal and if lightning is going to hit its going to hit it first Its much taller and metal. Having a couple ground rods to have a path to ground may keep it from damaging things in my home. I don't want the full brunt of the lightning traveling through my service wire back to my panel in the house.

Thought I'd chime in here on the "ground" as you have the wire size pretty much covered. DO NOT SINK A GROUND ROD!!! You will be grounded through the rod at your main panel and if you ground at a separate rod at your detached garage you have created a ground loop. It's laborious to explain why a ground loop is a bad idea but you'd find out during the next electrical storm.

[Lloyd Smale]

that is the allox I was referring to in my post. Its just a brand name for it. Most electrical codes demand you use it and they will check.

You have to use deoxidation paste on all aluminum wire by the way I wire for a living.

[lightman]

It looks like I'm late to the party. The OP posted that he is buying #1 and has not been back in a few days. It looks like we are building his job after the fact. But its fun, so I'll play. I ran the numbers and #1 copper or 1/0 aluminum will carry a full 100 amp load with an acceptable voltage drop for the distance the OP stated. I added a few extra feet for up and down the wall. I would put the wire in conduit if given the choice. The #1 would go in 1-1/4 but the 1/0 would be a tight pull. I probably would go 1-1/2 or even 2 inch. The proper fittings on each end (think LB) would provide an easy way to enter and exit the buildings. Cost; the copper would cost me about $450 and the al would be about $110. 2 inch conduit would run about $55 and the required fittings would add maybe another $20. These are local prices and are just off the top of my head, but will be close.

There are as many ways to do this as there are electricians. You can blow or suck a paper towel and a string through with a shop vac, but I would just use a fish tape. I'm not a fan of aluminum, but I've been trained to install it and have used it for 35 years. You need to wire brush the ends, treat it with an oxide inhibitor and torque it to the specs on the lug. The lug also needs to be rated for use with aluminum, but most are. Copper is much more forgiving and would be my personal choice. I would drive a ground rod at the shop and the shop panel would have the neutral and ground separated. A piece of 12-3 added for a 3-way switch from the house to shop would be a nice touch!

I'm a retired Journeyman Lineman and a Master Electrician. Yeah, I hold both cards and was active in both trades!

[lightman]

LLoyd, thats the stuff most Linemen have on the fronts of their shirts! Around the belly!

[Greg]

hey -

I'm still here, just watchin and learnin

I do appreciate all the responses

again, thank you for your help

[MaryB]

Chep insurance, add a whole house surge suppressor at the panel. It won't stop a direct hit but it will keep a near miss from frying motors, lights, etc in the shop

[Lloyd Smale]

ive still got a few shirts in the closet with those stains because all the connectors we used on the pole came with it in them. really though our meter techs did most of the wiring at the house. Once in a while when they were busy we did it for them.[

LLoyd, thats the stuff most Linemen have on the fronts of their shirts! Around the belly!

[Akheloce]

A few unasked for cents from a Journeyman Telecom guy...

Don't run phone line with the power if you have, or ever intend to have DSL at the house. I can't tell you how many repair tickets I've been on where the customer ran cat 3/5 or whatever in the same conduit as power over to their garage. The power influence kills DSL. The customers get confused because the modem is in the house, not the garage... However if the phone line in the garage is tied to the phone line in the house, they might as well be on the same physical wires.

Also, I was watching this thread with interest in regards to the ground loop issue. In my world, ground loops are bad, and play havoc with G.SHDSL data circuits. In some areas of my service area, the difference of potential between the Wire Center Earth Ground and the customer Earth Ground may be as much as 40V. A technique to alleviate this issue is to remove the earth ground from the equipment, and instead, bond it to the cable sheath (bonding it to the wire center).

[lightman]

Would a shielded cable laying in the same trench with a little separation work ok? Just curious.

[Akheloce]

Shielded is better than not, but it still will cause interference. Think about the milliamperes used in communications vs the 100+ Amps used in power. In a perfect world, your phone line would be at least 12-24" from all power when running parallel- or crossed @ 90 degrees.


Story comes to mind...

One customer had 7Mbps ADSL, but was only getting 4Mbps on a speed test. They had a decoratively manufactured log house.

Removed all house wiring, clipped my test set, and got full speed. Reinstalled one line of house wiring, and got 6 Meg. Reinstalled another, and got 5M. As I laid down each line of house wiring (I'm working in the box on the side if the house), I lost more speed.

As I investigated the house wiring, I noticed the phone jacks and the power outlets were located on the same log.

When a log house is wired, typically a router is run along a log as it is built, hidden from view when the next one is stacked. If the power and phone outlets are on the same log, then the wires were run in the same router channel (bad).

The cat 5 house wiring was shielded.

When I explained this to the customer, she was understanding, but unwilling to accept the fix, which was to drill holes in her new log house, and install new phone lines.

[TheCelt]

you will already have your ground loop with the utility pole in your front yard. All primary voltage poles are ground and have a ground rod. At least they do in our utility. Adding a ground rod at every enterance gives a shorter path to ground if you have a lightning strike. In our untility and going by our electrical standards for the county EVERY entrance to a building that has a panel has to have two ground rods. Tak my yard. I have a great big pole barn right near the house. Its metal and if lightning is going to hit its going to hit it first Its much taller and metal. Having a couple ground rods to have a path to ground may keep it from damaging things in my home. I don't want the full brunt of the lightning traveling through my service wire back to my panel in the house.

I'm not so sure we're talking about the same thing here. There is no ground loop until you create one. If you tie Neutral to ground at the main panel, sink another ground rod at your sub panel and tie neutral to ground at your sub panel you have created a ground loop.

The danger lies in the fact that you now have two points of ground reference for both panels. If there is a lightening strike in the area each ground sees a different potential. The nanosecond difference in potential is what does the damage.

As previously mentioned a ground rod is required at each panel. Neutral and ground are only tied at the main panel and NOT at the sub panel. This avoids the ground loop and the ground rod at the sub panel increases the ground plane of the original ground rod. In the event of a lightening strike both ground rods see the same potential (which is what you want).

[popper]

http://www.powerstream.com/Wire_Size.htm for reference. Note the difference in current rating for 1/0 = the transmission rating is the one to use in the OPs application.
Safety wire/neutral/ground rod requirements are NOT for lightning protection!! Completely different techniques. As for data, consider the power lines as a long wire antenna, they pick up everything plus transients from everything turning on/off. Only solution is shielding and separation for data lines - and avoiding ground loops.

[TheCelt]

http://www.powerstream.com/Wire_Size.htm for reference. Note the difference in current rating for 1/0 = the transmission rating is the one to use in the OPs application.
Safety wire/neutral/ground rod requirements are NOT for lightning protection!! Completely different techniques. As for data, consider the power lines as a long wire antenna, they pick up everything plus transients from everything turning on/off. Only solution is shielding and separation for data lines - and avoiding ground loops.

You are correct popper, ground rod are not for lightening protection, I didn't say they were. I did say that if you ground your sub panel and tie neutral to ground (at the sub panel) you will have a ground loop and a difference of potential at the ground points in the event of a strike nearby.

[lightman]

Akheloce, Thanks for the info. I quit wiring houses before DSL, so my question was for my education only. Inquiring minds, Ya know! Around here we once had a contractor that worked for us ( power company ) and the phone company and there are a lot of phone drops buried in the same trench with the power. Thankfully mine is not.

[gew98]

I F you use aluminum, remember to tighten the lugs every year. Heat causes aluminum go get loose.

And use NO - OX on your lug/wire lugs. I use it like religion and it saves alot of later down the road dissimilar metals corrosion . For the past couple years two ground rods within 10 foot of panel and each other with bare or insulated # 6 awg minimum on such a panel size. You need to check in your AO if this needs an inspection or not. Some local inspectors want more than NEC code and could cause you grief on a do it yourself install "they" deem inappropriate , an dif you argue with them they will show you they can exceed NEC code by law and make it real hard on you getting inspected and passed timely and on budget. And take the advice on bonding.... seen the results of bonding from lineside to panel where a neutral failed and the ground that should not have been there became the neutral and it caused a fire instead of kicking out the supply as it was way undersized to handle that panels max load. Oh and PVC schedule 40 for underground...direct burial is in the code...but you really want to avoid that.

[gew98]

Don't try pulling 300 or 500 MCM with a rope.

I've pulled up to 750's with a rope on some 600' runs. Gobs of lube and thankfully few bends. Just have to know what you are dealing with. I saw a fella one day cut the manufactured head off a high dollar spool of pool rope...yeah he got canned on the spot !. I've had twined pull rope break and had to reweave the head...time consuming yes.... but gives the feet a rest to reweave and get ready for the pull !. I always jet a pipe run with a compressor before I even put a string & mouse in it. Have found everything from rocks , mud , screws , drillbits and even dead critters ( blown from the undergound lines )

[MaryB]

I helped my dad(he was an electrician) with a pull like that. We were wiring a roller skating rink and had to do the pull by hand. I was put on the lube bucket and dad told me to waste it, make it wet! We ended up with 6 guys on the rope to pull through 2 90 degree sweeps.