Electrical subpanel project

[Skinnywater]

I'm out of my rhelm a little here.<br /><br />My home has 200amp service. I want to come off of that panel and run straight down a gravel driveway 210 foot to a subpanel just outside of an existing shed.<br />In the near future that shed will be added onto.<br />Future consumers will include an air compressor, an above ground hoist, grinder, parts washer and some lighting. Nothing very extravagent or heavy outside of the compressor.<br />I will pull a permit for the electric. Cost is a factor and I realise the greater the current the higher the price, so I don't want overkill.<br /><br />From what I've learned and I'll study it further, The conductors should be in conduit 18inches under grade, surrounded by 4in of sand.<br />My immediate questions;<br />I'm thinking 100amp will do it?<br />What size conductors and type?<br />How big the conduit?<br />Approx. cost of materials?<br /><br />Thanks much for the advice.

 

[Bondo]

Re: Electrical subpanel project

For a Shop,... I'd carry the Full 200amps,......<br /><br />The Size of the wire will change for Copper or Aluminum,....... I'd Guess 6ga or Bigger.......<br /><br />Up here you can use a "Direct Burial" cable,... No Conduit.......<br /><br />The Sand is Cheap Insurance,.... We also lay a strip of plastic Caution Tape on top of the Sand,...... It gives the Next Guy a heads up that he's about to dig up a wire........<br /><br />Co$t$,..???......

 

[heyttown]

Re: Electrical subpanel project

I say spend the few extra bucks and install conduit (pvc) if allowed in your area. Also if your subject to electrical inspections they could tell you the proper burrial depth for the conduit.... <br /><br />100 amp service with that distance of a run should have #2 awg copper wires. I would run at least a 2" conduit,the bigger the pipe the easier the wire will pull....<br /><br />Remember, Any panel after the main panel has to have seperate (isolated)neutral and ground bars...Very common problem with DIY projects that gets overlooked....<br /><br /><br />Just remember,you may save a few dollars with running direct burial cable(probably wont save a whole lot),but you could run conduit, and if you ever had a problem with a wire underground,you could disconnect the wires,pull the old wires out and pull new wires in.If you direct burial,you would have to redig another trench to lay more wire down.....<br /><br />If you feel that the shop could eventually be pretty big, and the small possibility that you may outgrow your new subpanel,you could always over size your pipe for the future.<br /><br />Also while the trench is open run a smaller pipe in the same trench 1" or so for phone/cable lines...<br /><br />Again these are all suggestions, and I like to try and think ahead....Sure I probably overkill somethings,but it has saved my butt on numorous other times for the overkill.

 

[sangerwaker]

Re: Electrical subpanel project

Not a licensed electrician here, Skinnywater, but I think I can get you pretty close. Please, any of you tradesman, if I botch this up, please let me know.<br /><br />First, be sure to brush up on your local codes, as I'm basing my recommendations on what I see used around here.<br /><br />I think 100 amp should do you fine. Most 240 volt welders use 50 amps, and a larger 240 volt compressor will usually be 20 or 30 amps at max. You're correct on the piping, and I'd recommend 1-1/4" minimum PVC. If you go up 1 size, your wire pull will be easier, though. I don't have a wire fill chart at home. I'll check for sure at work tomorrow.<br /><br />As for the conductors, I'd recommend type THHN copper. You could use aluminum (type XHHW probably 1 AWG). With the copper, you'll need 3 AWG due to the voltage drop.<br /><br />Cost of the materials would be a breeze for me if I was at work right now, so I'll make a list and add a guesstimated price.<br /><br />100 amp breaker for house panel 40.00<br />Sub panel 100 amp main 20 space 60.00<br />210' conduit and fittings 150.00<br />630' (210x3) 3 AWG THHN CU 600.00<br />210' 6 AWG ground wire 90.00<br />Ground bar for sub panel 8.00<br /><br />TOTAL 948.00 ?????<br /><br />I'm totally basing my pricing on local prices here. Your pricing may be VERY different locally. Also, my pricing does not include any circuits in the new panel.<br /><br />Be aware that PVC pipe has recently skyrocketed in cost and going up again soon. Buy the pipe now if you plan on doing this any time soon.<br /><br />EDIT-heyttown, I see you recommended #2. How much (percentage wise) is too much voltage drop?

 

[divo]

Re: Electrical subpanel project

Thats a long way to go with 100 amps. the wire alone will probably be over $1000.00. If it were me, I would put a seperate service on it. Where I live the power company will go usually about 120 feet for free. You would have a small monthly meter charge. You could have the whole thing done for under $200.00 if you do it yourself.

 

[one more cast]

Re: Electrical subpanel project

Man I don't know where you guys buy your supply's but I just went 100' direct burial 100 amp all to code to my garage this spring for around $250. Edit: I forgot about the second ($150) trip for supply's. Make that $400.

 

[sangerwaker]

Re: Electrical subpanel project

I'm the only one putting up numbers OMC. I'm totally winging it on cost and I'd rather put too hig of a number up there. I sell this stuff everyday. My costs on the wire are high, but I'll verify replacement cost at work tomorrow and edit in current actual prices.<br /><br />Copper prices have continually risen all year. I have never seen wire higher than it is right now. Just for all you guys who can appreciate this, 500 MCM is over 5.00 per foot! I can remember selling that same wire for under 2.00 per foot not more than 5 years ago!

 

[craze1cars]

Re: Electrical subpanel project

I'm not real knowledgeable on this but am curious....Would aluminum mobile home feeder cable be an option for this run? I believe it is OK for direct burial, and would be quite a bit less expensive than copper. Seems to me I saw some 4 conductor spools recently (2 awg???) for around $2/foot (for all 4 conductors) at a home improvement store...I could be wrong on that, though. Not sure what code has to say about it either.

 

[crab bait]

Re: Electrical subpanel project

# 1 alum awg is for 100 amps.. so would think that # 1 copper would work with the voltage drop.. <br /><br />same size in copper's like goin' to the next size up in alum..<br /><br />since the new panel is a sub panel,, must run 3 conductor an/with ground.. ( must have a white wire/nuetral ) ..2 hots one white an ground..<br /><br />an a ground bar installed in subpanel ( 4 bucs extra ) to keep all white an grounds separate ..<br /><br /> all white's land on the panel's insulated buss bar ( as came from factory )..<br /><br /> ALL grounds land on the new 4 buc ground bar..<br /><br />DO NOT INSTALL the 'bonding screw' supplied with the panel.. this srcew bonds the white's insulated buss bar with the new 4 buc ground bar..<br /><br /> NOT WANT THIS TO HAPPEN..<br /><br />it must be used in a main/first panel.. but that's all..<br />if'n you need a permit,, you'll need an inspection.. talk with the inspector .. he'll help you..

 

[one more cast]

Re: Electrical subpanel project

sangerwaker, I edited my above post and you are talking copper and over 200' so I beleive you may be close on your price.

 

[sangerwaker]

Re: Electrical subpanel project

Crab, you do commercial work don't you? In resi applications, you can derate 1 wire AWG. Most contractors use #4 THHN copper or #2 XHHW aluminum around these parts for 100 amp resi services. You would need to go 1 (possibly 2) sizes larger due to the length of the run and subsequent voltage drop.<br /><br />As for the pricing I said above, I was pretty close. Take about 100 bucks off the 630' of #3. It will go right back up there if you were to use #2 or #1. So my new total for you, Skinnywater, would be roughly $850 if you use #3 copper and 1-1/4" PVC. I verified all the costs since I'm now at work and have access tou our mainframe.<br /><br />EDIT- Just found the info I was looking for. NEC will only allow a 3% voltage drop over the course of your run. Looks like you'll need to run #1 copper. I used this voltage drop calculator. <br /><br />This puts the copper wire cost at closer to the $800 mark. That's not including the #6 for a ground wire. You'd also need to use larger conduit to accomodate the larger wires. If you went aluminum, you'd need 2/0, according to the calculator. 630' of that would be about 300 bucks.

 

[Ron G]

Re: Electrical subpanel project

If you put aother service on the garage around here its considered to be commercial so the codes change to commercial wiring,and if the 100 is not enough the future you could always get a motor and run 3 phase,all my electricl is real rusty and stuff changes constantly.

 

[divo]

Re: Electrical subpanel project

If the trench is 210' the wire will have to be at least 10' longer on each end.that makes it 230' x 3. if you use aluminum wire in pvc conduit you will regret it.

 

[sangerwaker]

Re: Electrical subpanel project

Please give us more info divo. Why?

 

[divo]

Re: Electrical subpanel project

alum wire does not pull well. especially in pvc, and over that distance. even lubed up...you will burn through the 90% s. you will have to pull the wire back out and put in rigid 90%'s. you will need a truck and a large tree with a pulley over one end of the conduit to pull that size alum wire. when you put 4 of the them together....it doesnt bend very easy. he needs to get an accurate wire measurement....not just how far it is from house to new panel. If the new servive is not an option, i would check into the price of an alum. four-plex direct burial cable. If you are going under the driveway...omit the four-plex...use conduit and bury it 24"

 

[sangerwaker]

Re: Electrical subpanel project

Why one would regret using aluminum conductors inside PVC conduit. Contractors do it here every day.

 

[divo]

Re: Electrical subpanel project

Originally posted by sangerwaker:<br /> Why one would regret using aluminum conductors inside PVC conduit. Contractors do it here every day.

In my neck of the woods...nobody uses it. I have 20 years in and have never pulled alum. wire in conduit. It's considered "hack job". Most job specs say....cu only. I have repaired many alum wire terminations. I will never install it!!!!

 

[Skinnywater]

Re: Electrical subpanel project

Excellent guys, I'm taking it all in.<br />Here's where I'm headed from most of you.<br />2 inch conduit and 3x #1 CU and #6 ground.<br /><br />A local supply is really pushing the AL 2/0. A sheathed pack of 3 conductors and ground and is direct burial. Mostly on the cost savings. <br />I will have to run it through the conduit because of the driveway.<br />I was warned about the difficulty in pulling it.<br />210 foot was panel to panel.<br /><br />Is this the 4 plex and will it pull with 2" conduit? There should only be 3-90's at the ends that can be assembled below and at the panels.<br /><br />Hmmm, $900 with copper or $400 in aluminum??<br />Is this a simple choice or what is the practical pro's and con's here?

 

[sangerwaker]

Re: Electrical subpanel project

divo is right, the aluminum will not bend as easily. I've never heard of someone in this area using aluminum in PVC called a "hack". Might be different in different areas, dunno. Personally, I don't foresee any problems using aluminum, but I haven't done many actual installs and have always used copper.<br /><br />If you decide to use the aluminum, be very sure to use an anti-oxidizing compound in the lugs where terminating the aluminum wire. Also be sure to tighten the lugs WELL. Recheck them in a couple of months.<br /><br />Also, be sure to check with your inspector. I don't believe you can put a direct burial rated cable inside of conduit.

 

[magster65]

Re: Electrical subpanel project

I have a 200 main with a 100 amp breaker running to a 100 amp panel in the garage. It was a run of about 75 feet (I chose copper over the aluminum for it's corrosion resistance) and I ran it in 2" conduit (2 - 90's / 2 - 45's / 1 LB). Your building code will give you wire size requirements / per distance / per loading. In the shop I have a wire feed welder, electric heat, hot water tank, fridge, stereo, tv, 16 double flourescent fixtures... I've had all that stuff on at the same time (or close to it) and have never seen a light flicker yet.