(206) 949-5683, Top Rated Plumber, Seattle
Page 1 of 4 1234 LastLast
Results 1 to 15 of 46

Thread: Looking for some help on garage sub panel

  1. #1
    DIY Junior Member knied1's Avatar
    Join Date
    Aug 2012
    Location
    WNY
    Posts
    14

    Default Looking for some help on garage sub panel

    This subject may have been beaten to death, but here is my plan, and I have a couple questions.

    I am running a sub panel to my garage, I have already purchased the panel box for the garage from Home Depot, it was on sale, and included the 100amp main, 1 - 30 amp (240) and 2 – 15 amp breakers. My garage is detached from the house, and total run from box to box is almost 50 feet. I currently have 100 amp service to my house, but am planning to upgrade to 200 amp in the next year or 2. I understand that I can only send 50 amps to the garage (half of my service) but I want to put 100amp wire / cable depending on what you prefer to call it, and sub panel, this way when I upgrade my service I am all set to send more power to the garage. I also know I need a permit, and an inspection, the permit is $100, and inspection is $68, cheap enough to not risk burning down the house i WILL be getting them. My town code DOES allow for the home owner to do the work I just need an inspection to close out the permit.

    This is my plan, and I am asking this so that I can have 100% everything ready and done only one time, so your input will be appreciated.

    • 2-2-2-4 aluminum (Home depot called it 100amp feed, I may have the numbers and dashes wrong I’m going by memory, but I am planning to use aluminum 100 amp feed)
    •1 ” pvc conduit buried 18” deep ( I understand I can use 1 but I figure 1 ” would be easier to pull the wire)
    o I have not purchased the wire or conduit yet would it make sense to run 2” conduit?
    o There will be about a 15 foot run inside the house. Is this supposed to be in conduit?
    • 50 amp breaker in my house panel, and leave the 100 amp in the sub panel in the garage, using it as a main disconnect, but I will label the box as 50 amp house supply.
    • Since I am running 4 wire I understand I need to tape both ends of one wire white marking it the common, obviously one wire to either side to the 50 amp breaker, and the other to the ground.
    o I am running 4 wires I am being told I do not need a grounding rod at the garage, and if it put one there I am increasing my risk of lightning strike. Is this true or was someone having fun with me?

    What am I missing? understand that i am also planning to upgrade my house service, and want this install able to accomidate future upgrades.

    I am planning to run a welder, and just the basic home shop type tools. I currently only have 20 amps of service in my garage, and am sick of using my generator welder. This will allow me to get rid of that, and pick up a regular 240 volt.

    Thanks for any help you can offer please understand that I am not up on the electrical lingo, and may ask some questions that seem dumb.

  2. #2
    DIY Junior Member knied1's Avatar
    Join Date
    Aug 2012
    Location
    WNY
    Posts
    14

    Default

    sorry one more question
    I am told that the common and ground wires CAN be on the same bussbar in the house, BUT the ground and neutral need to be on separate bussbars in the panel. Is this true? and what is the difference?

  3. #3
    Electrical Contractor/Instructor jwelectric's Avatar
    Join Date
    Jun 2007
    Location
    North Carolina
    Posts
    2,522

    Default

    2-2-2-4 for a remote panel is good for only 90 amps so installing a 90 amp breaker will be good for now or after the service is changed.

    If the conductors are to be installed underground make sure that there is a W in the lettering on the conductors. If they are selling you URD or trailer cable as some call it, it cannot enter either building. Set a junction box on the outside and terminate the URD and install SE-R four conductor cable to the panels.

    Unless it is a cable it will need to be in pipe from end to end. If it is part of a cable it must be type UF.

    If it is aluminum conductors then all four must be insulated and identified by tape for the equipment grounding conductor green and for the grounded neutral with white or gray.

    At the garage a grounding electrode system must be installed. If there is none available then drive two rods at least 6 feet apart and install a grounding electrode conductor to them. This conductor can be a solid uninsulated conductor.

    The use of the word common is not correct. The four conductors will consist of two ungrounded (HOT) one grounded (neutral) and one equipment grounding conductor. In the remote panel the neutral and EGC must be isolated from each other with the grounding electrode conductor landing on the EGC terminal bar which will be bonded to the panel enclosure. The neutral will need to be isolated from contact with the grounding.

    Just for the record there is no such thing as a
    Quote Originally Posted by knied1 View Post
    and may ask some questions that seem dumb.
    All questions are needed when doing something that one lacks knowledge about. Where the problems with questions comes into play is when someone is told that something will not work but one keeps asking questions about how to do it. If it cant be done why keep asking questions? These are the dumb questions and you have not asked one yet so keep them coming.

  4. #4
    Electrical Contractor/Instructor jwelectric's Avatar
    Join Date
    Jun 2007
    Location
    North Carolina
    Posts
    2,522

    Default

    Quote Originally Posted by knied1 View Post
    sorry one more question
    I am told that the common and ground wires CAN be on the same bussbar in the house, BUT the ground and neutral need to be on separate bussbars in the panel. Is this true? and what is the difference?
    The difference between the grounded neutral and the equipment grounding conductors are as follows;
    The grounded neutral conductor is a current carrying conductor that completes the circuit from the transformer back to the transformer just as the way a flashlight works. From the end of the batteries through the light bulb back to the batteries.

    The Equipment Grounding Conductor is installed in the event that there is a fault in the system where exposed metal will be energized it will carry the faulted current back to the source in order to open the overcurrent device be it a fuse or breaker. The only time the EGC will carry current is when something goes wrong.

    The two are tied together in the service equipment where the fault current travels from the service panel to the transformer via the neutral. The equipment grounding conductor does not carry current unless something has gone wrong.
    If the two are tied together anywhere downstream from the service then they both will have current on them making any exposed metal between the two points hot.

  5. #5
    DIY Junior Member knied1's Avatar
    Join Date
    Aug 2012
    Location
    WNY
    Posts
    14

    Default

    jwelectric thanks for the input but i need to hit you up again.

    The wire is 4 wire aluminum, and all 4 wires are insulated individually, one has a yellow stripe. I understand that i need to be sure of the W, or UF labeling on the wire before i purchase it, and 90 amps is more than enough for what i am planning. This being said...... he told me i only need 1 1/4" conduit, but i am assuming it would be easier to pull the wire if i went with 1 1/2" or 2" conduit. the difference in cost between 1 1/4" and 2' is sooo minimal i do not care about the few extra dollars, and does the conduit need to continue into the house all the way to the panel? What would you recomend for conduit? At the same time is there a different wire you would recomend for a DYI`er. I want the wire in conduit incase i need to pull something like a phone line, or need to replace wire things like that. (planning on PVC conduit)

    As far as the grounding rods....You are saying 2 rods 6 feet or more apart, do I run 1 wire to each? or wire to the one rod, and then a jumper for lack of a better term to the other. I am also assuming the rods need to be 8 feet long.

    thanks again
    Last edited by knied1; 08-31-2012 at 08:08 AM.

  6. #6
    Electrical Contractor/Instructor jwelectric's Avatar
    Join Date
    Jun 2007
    Location
    North Carolina
    Posts
    2,522

    Default

    The bigger the conduit the easier it will be to pull. What you don’t want to do is install a low voltage conductor in that same conduit be it telephone or cable as it is neither the voltage rating and it will distort the signal. For these run another 1 inch conduit.

    If the conductors are single strand conductors and this sounds like what you describe then it will need to be in conduit from end to end but if it is URD again it sounds like what you describe then it can’t enter either building so a junction box will need to be set and transitioned to another type of conductor. I suggest 2 SE-R cable for entering either of the buildings. This can be 2-2-4-4 or what ever they have on hand as long as the first two numbers are 2.

    Yes two 8 foot rods at least 6 feet apart and you can install one conductor to the first rod and then install a “bonding jumper” to the second rod.
    Last edited by jwelectric; 08-31-2012 at 09:03 AM. Reason: for corrections

  7. #7
    DIY Junior Member knied1's Avatar
    Join Date
    Aug 2012
    Location
    WNY
    Posts
    14

    Default

    How far are you allowed to run URD inside a structure?

    In the garage i would need to run it about 3 feet, to the panel, and in the house it would be about a 10 foot run into the panel. It seems to me it would be safer to have one run for panel to panel instead of 2 junction boxes, and splices.


    Thanks

  8. #8
    Electrical Contractor/Instructor jwelectric's Avatar
    Join Date
    Jun 2007
    Location
    North Carolina
    Posts
    2,522

    Default

    Quote Originally Posted by knied1 View Post
    How far are you allowed to run URD inside a structure?

    In the garage i would need to run it about 3 feet, to the panel, and in the house it would be about a 10 foot run into the panel. It seems to me it would be safer to have one run for panel to panel instead of 2 junction boxes, and splices.


    Thanks
    URD cannot enter either building for even one half inch. In the event of a fire the insulation is toxic.

    If you want to run from panel to panel the use THW conductors, the price will be a little higher but the benefits outweigh the price.

  9. #9
    General Engineering Contractor ballvalve's Avatar
    Join Date
    Dec 2009
    Location
    northfork, california
    Posts
    3,258

    Default

    I often slide the conduit over the wires, then set the whole run, so as to not have the burden of some glitch in a long pull. Can use smaller conduit also.

  10. #10
    DIY Senior Member Homeownerinburb's Avatar
    Join Date
    Jan 2012
    Location
    Los Angeles, CA USA
    Posts
    505

    Default

    Quote Originally Posted by ballvalve View Post
    I often slide the conduit over the wires, then set the whole run, so as to not have the burden of some glitch in a long pull. Can use smaller conduit also.
    Strictly speaking, a violation of code. I expect because metal conduit would likely abrade insulation without the proper connectors in place.

    Not really much of an issue with plastic, I suppose, and I confess I have done it both with plastic and emt.

  11. #11
    DIY Senior Member Homeownerinburb's Avatar
    Join Date
    Jan 2012
    Location
    Los Angeles, CA USA
    Posts
    505

    Default

    Quote Originally Posted by knied1 View Post

    I am running a sub panel to my garage, I have already purchased the panel box for the garage from Home Depot, it was on sale, and included the 100amp main, 1 - 30 amp (240) and 2 – 15 amp breakers.
    I have absolutely NO idea why you think you need 100 amps out in the garage. I have installed a few 50 amp services for real gear heads, but most guys are happy with a 30 amp service. Square D makes a great little panel with six slots. Two slots for the 30 amp main (or 50), two more slots for a 240v circuit, one 15 amp circuit for the lighting, and one 20 amp circuit for all the power tools not of 240v.

    IF you want AC as well, some tandem breakers will fit fine. Same for a fridge, if you must.

    Are you intending to run a factory in there? How many guys will be working simultaneously? How many of your power tools can YOU work simultaneously?

    The Square D panel costs about $17 at Home Despot. I swear by it.

    Seriously, what sort of power demand do you think you are laying on the system?

    You do understand that when you say "100 amp" that means two 100 amp 120v circuits, yes?

    You could hold electrocutions in there based on your plan.

    My whole 1800 sq ft home with a 4 ton AC in LA runs on a 100 amp panel.

    You are way over killing this project.

  12. #12
    DIY Junior Member knied1's Avatar
    Join Date
    Aug 2012
    Location
    WNY
    Posts
    14

    Default

    I know that immediately I am over killing it, BUT within the next few years I am going to have a mill, and lathe in the garage, before you call me out they are both single phase 220. My father is retired and when he sells his house I can have them…….. Right now my son and I work in the garage at the same time, I know I am doing the welding, and he is grinding or cutting…... When I get the machines in there it is very possible I will be working on one, and he will work on the other.
    If I am going to do the work now to send a feed to the garage it seems stupid to only send 30amps out there so that in a few years I can tear it all out and do it again.
    Yes for the next year, two, three, I will only have a 50 amp breaker for 100 amp line, but at least I am ready. When the time comes all I would have to do is switch out breakers and the garage is all set, and if my plan falls thru then I only spent maybe an extra $100, and not re-spend several hundred. I know I bought the panel too early, but it was on sale for $28.00 and included all the breakers. I have not bought the conduit or wire yet.
    Will I need a full 100 amps?..... I don’t know…… I DO respect your opinion, and appreciate the fact that you may be trying to save me money, and hassle, but my opinion is if I’m going to spend the time and money, I may as well make sure I only have to do it once.

  13. #13
    DIY Junior Member knied1's Avatar
    Join Date
    Aug 2012
    Location
    WNY
    Posts
    14

    Default

    Quote Originally Posted by jwelectric View Post
    URD cannot enter either building for even one half inch. In the event of a fire the insulation is toxic.

    If you want to run from panel to panel the use THW conductors, the price will be a little higher but the benefits outweigh the price.
    When i was at Home Depot last night looking into their different wires I told them that i did not want the URD, and wanted THW. There was an electrition there and he told me it was ok but only inside of conduit...... I am planning to call the town building inspector, but i am just looking to clarify. When you recomend that urd cable should not be inside the structure, does that only mean without conduit? on a side note they do not have THW, i would need to go to an electrical supply house, but if that is what i need to do then ill do it.

    Thanks again for all your help.

  14. #14
    DIY Senior Member Homeownerinburb's Avatar
    Join Date
    Jan 2012
    Location
    Los Angeles, CA USA
    Posts
    505

    Default

    Quote Originally Posted by knied1 View Post
    When i was at Home Depot last night looking into their different wires I told them that i did not want the URD, and wanted THW. There was an electrition there and he told me it was ok but only inside of conduit...... I am planning to call the town building inspector, but i am just looking to clarify. When you recomend that urd cable should not be inside the structure, does that only mean without conduit? on a side note they do not have THW, i would need to go to an electrical supply house, but if that is what i need to do then ill do it.

    Thanks again for all your help.
    No, the URD may not be in the building at all.

    You indicated that you were going to lay in conduit. Use thwn in the conduit. Make sure it is marked with "w" for wet.

    And the thwn must be in conduit from one panel to the other, every inch of it.

  15. #15
    DIY Senior Member Homeownerinburb's Avatar
    Join Date
    Jan 2012
    Location
    Los Angeles, CA USA
    Posts
    505

    Default

    Quote Originally Posted by knied1 View Post
    If I am going to do the work now to send a feed to the garage it seems stupid to only send 30amps out there so that in a few years I can tear it all out and do it again.
    Of course you should only do the work once and anticipate your future needs.

    Based on what you are saying here, yes, 30 amp is possibly too little.

    As for the mill and the lathe, they are 240v. You understand, I hope, that that means that they draw half as much ampacity on the hot leg(s), yes? If the same motor is wired to run at 120v and it is eating 5 amps (which is a big motor) at 240v it will draw 2.5amp per leg.

    Go find out how much the lathe and the mill draw. I bet combined they don't add up to more than 20 amps.

    Likewise the welder you want to use and the grinding and cutting. The grinding and cutting happens at 120v.

    You can go ahead with your enormous panel, but I am quite sure that you don't need more than 50 amps out there.

    As I say, I have a 1800 sq ft house with a 4 ton ac in LA running without any difficulty on a 100 amp panel.

    How you think you need more than half that is a mystery to me, but I'll let the other guys chime in.

Similar Threads

  1. Wiring a garage
    By sirjonas in forum Electrical Forum discussion & Blog
    Replies: 11
    Last Post: 10-15-2011, 03:41 AM
  2. sub panel to garage
    By pbprice in forum Electrical Forum discussion & Blog
    Replies: 4
    Last Post: 04-02-2011, 07:46 AM
  3. Using just a screwdriver to change out a 100 amp main panel to a new 200 amp panel
    By Ian Gills in forum Electrical Forum discussion & Blog
    Replies: 8
    Last Post: 05-19-2010, 06:08 AM
  4. Moving main panel to detached garage
    By Lakee911 in forum Electrical Forum discussion & Blog
    Replies: 10
    Last Post: 10-06-2009, 07:26 AM
  5. Help with garage plumbing
    By 67restoproj in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 2
    Last Post: 05-02-2008, 04:33 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •