Posted: 6/22/2012 9:41:42 AM EDT
|
I am thinking about wiring my 10ft x 20ft detached shed for power and want to run my process by you guys. I am going to use a 100 amp subpanel which will be fed from either a 60 or 100 amp double throw breaker from my 200amp main panel. I will need to run about 30-40 ft of romex wire from the main panel to a junction box in the attic there I will splice it to either #6 or #3 THHN/THWN (depending on wether I use a 60 amp or 100 amp breaker), then run another 30ft of 2 hots and 1 neutral of THHN/THWN through a 1 1/4 inch PVC conduit which will be buried 18 inches underground.
I will use #8 wire as a ground near the subpanel which I will attach to 2 grounding rods at least 6ft apart. I will need to isolate the neutrals from the ground as the installation will be in a detached building with it's own ground. I will installing eight 20 amp receptcales for power on a 20 amp breaker, the first receptacle will be a 20 amp GFCI receptacle and the rest will be wired in seires. Five sets of 48 inch flourescent shop lights on another 20 amp GFCI circuit breaker. Lastly I might install a 30 or 50 amp 240v receptacle in case I want to buy a small welder in the future which will protected by either a 30 or 50 amp breaker depending on what plug I decide to go with. I will be doing the installation and applying for the permit, but I will be hiring an electrician to connect my wiring to the main breaker and inspect my work. I am currently reading the NEC guide and I am not an electrician so some of the things I want to might be wrong. 
What size romex do I use for the 30 ft run from the main breaker to the junction box in the attic, assuming I will use the 100amp breaker? Is #3 THHN/THWN big enough for 100 amps? Is there anything you see wrong with my plan? |
|
#3 will be fine, even for a 90' run. Rather than Romex inside, continue with conduit, if it is tough to get straight runs, use something like sealtight or greenfield (Flexible Metallic Conduit) to your panel. Then you won't need to use lugs, to put two pieces together.. Depending on how many bends you have, you may need to use a pull box anyway, this would be where you could join your PVC to the Flex. |
|
Quoted:
I am thinking about wiring my 10ft x 20ft detached shed for power and want to run my process by you guys. I am going to use a 100 amp subpanel which will be fed from either a 60 or 100 amp double throw breaker from my 200amp main panel. I will need to run about 30-40 ft of romex wire from the main panel to a junction box in the attic there I will splice it to either #6 or #3 THHN/THWN (depending on wether I use a 60 amp or 100 amp breaker), then run another 30ft of 2 hots and 1 neutral of THHN/THWN through a 1 1/4 inch PVC conduit which will be buried 18 inches underground. I will use #8 wire as a ground near the subpanel which I will attach to 2 grounding rods at least 6ft apart. I will need to isolate the neutrals from the ground as the installation will be in a detached building with it's own ground. I will installing eight 20 amp receptcales for power on a 20 amp breaker, the first receptacle will be a 20 amp GFCI receptacle and the rest will be wired in seires. Five sets of 48 inch flourescent shop lights on another 20 amp GFCI circuit breaker. Lastly I might install a 30 or 50 amp 240v receptacle in case I want to buy a small welder in the future which will protected by either a 30 or 50 amp breaker depending on what plug I decide to go with. I will be doing the installation and applying for the permit, but I will be hiring an electrician to connect my wiring to the main breaker and inspect my work. I am currently reading the NEC guide and I am not an electrician so some of the things I want to might be wrong.
What size romex do I use for the 30 ft run from the main breaker to the junction box in the attic, assuming I will use the 100amp breaker? Is #3 THHN/THWN big enough for 100 amps? Is there anything you see wrong with my plan? I see one thing right off the bat that is you need a seperate ground all the way back to the panel since the NEC requires 4 wires for a sub panel that being 2 hots, 1 neutral and 1 ground. |
|
I see one thing right off the bat that is you need a seperate ground all the way back to the panel since the NEC requires 4 wires for a sub panel that being 2 hots, 1 neutral and 1 ground.
I thought you only had to run 4 wires when the subpanel is going to be in the same building but if it is a detached building you wanted the detached building to have it's own ground. Is that in the 2011 NEC 250.30? ETA:I see that the changed the rule in NEC 2008 
|
|
Quoted:
#3 will be fine, even for a 90' run. Rather than Romex inside, continue with conduit, if it is tough to get straight runs, use something like sealtight or greenfield (Flexible Metallic Conduit) to your panel. Then you won't need to use lugs, to put two pieces together.. Depending on how many bends you have, you may need to use a pull box anyway, this would be where you could join your PVC to the Flex. I am going with the conduit from the main panel all the way outside to the shed as i don't have too many bends. |
|
If you plan to use discreet wire, just buy black and a package of colored tape to identify the ends of the different runs, neutral, hot, ground, phase, etc. This will save you money over buying 2 or 3 different colored wires. I always error on the side of caution and go one size bigger wire than needed. Plans can change over time............ |
|
Quoted: Quoted: Have you considered a second meter? No should I have been? I only need 60 amps to the shed but I want to future proof the installation so if that means installing thicker guage wire I will do it. Either way works. It's just a different method. It doesn't make sense in all applications, but more options are a good thing. My dad has a workshop in his backyard about 150 feet from the house. He had a second service installed from the power company, so he didn't have to run power from the house to the shop. Plus, the house didn't have the capacity to spare at the time. I believe the shop has a 100 amp service. If you aren't going to be using a lot of power out there, it might not be worth the second meter. |
|
Quoted:
Is there anything you see wrong with my plan? you already got the message about the 4 wire subfeed, so that is covered. 
a couple more things to think about: 1) while you have the trench open, put another conduit for low-voltage wiring such as a couple of lengths of CAT5/6, coax for a CCTV camera, and two-pair for an alarm loop. this way one day you can have cameras, controls, alarm contacts, etc out at the shop. i find it REALLY handy to know from the house that the shop doors and windows are closed, especially at 2am when i am laying in bed thinking whether or not i closed all the shop windows. 2) water to the shop can be REALLY handy, even if you don't have a proper drain. just the ability to hose off the tractor or what not close to the shop is handy. again, if you have the trench open, drop in a piece of black 200 psi poly –– you can always hook it up in three years and it's a hell of a lot easier than trenching again. 3) plan for some outlets and lights outside of the shop envelope, so you can work outdoors if it nice and late into the night if you need to. 4) an overhead-mounted pull-down trouble light/outlet is really handy, so be sure to put an outlet in the center of the ceiling for this purpose. 5) FINALLY, but perhaps very importantly, you may want to consider running additional wire FROM the workshop TO the house –– such that you can run a generator adjacent to the workshop and have it power the house via a transfer switch. i did this and in the end it has proven to be super useful. ar-jedi 
|
|
Quoted:
Quoted:
Is there anything you see wrong with my plan? you already got the message about the 4 wire subfeed, so that is covered.
a couple more things to think about: 1) while you have the trench open, put another conduit for low-voltage wiring such as a couple of lengths of CAT5/6, coax for a CCTV camera, and two-pair for an alarm loop. this way one day you can have cameras, controls, alarm contacts, etc out at the shop. i find it REALLY handy to know from the house that the shop doors and windows are closed, especially at 2am when i am laying in bed thinking whether or not i closed all the shop windows. I have security cameras mounted on my house that allow me to monitor my shed from my phone or from the house, my alarm is wireless and I have already installed sensors in the shed, and I can pick up my wireless internet signal from my shed. 
2) water to the shop can be REALLY handy, even if you don't have a proper drain. just the ability to hose off the tractor or what not close to the shop is handy. again, if you have the trench open, drop in a piece of black 200 psi poly –– you can always hook it up in three years and it's a hell of a lot easier than trenching again. My house has a water hose spigot right next to the shed. 3) plan for some outlets and lights outside of the shop envelope, so you can work outdoors if it nice and late into the night if you need to. This is part of current plan. 4) an overhead-mounted pull-down trouble light/outlet is really handy, so be sure to put an outlet in the center of the ceiling for this purpose. I already have this covered. 
5) FINALLY, but perhaps very importantly, you may want to consider running additional wire FROM the workshop TO the house –– such that you can run a generator adjacent to the workshop and have it power the house via a transfer switch. i did this and in the end it has proven to be super useful. That is my plan but I want to figure out my power plan first and then I'll tackle the gen wiring. I just ordered a 3500 watt generator from Cabelas it's small but it is all I can afford at this time. It will allow me to power my fridge, a few lights, and a small room A/C ar-jedi keep the ideas coming I need inspiration. I just rememered I need to plan for a small A/C for the summer.
|
|
AR-Jedi I have a 30 amp 120v gen would I use a SP circuit breaker or a DP? I'm thinking 30 amp SP.
ETA: new plan Shed power 60 amp DP CB in main box 6/3 NM from the main breaker to a junction box in the attic. I chose it since I can get it cheaper than the THHN 2 hots and 1 neutral 6 awg THHN/THWN from the junction box in attic through 1 1/4 pvc conduit to the shed 1 ground 10 awg THHN/THWN from the junction box in attic through 1 1/4 pvc conduit to the shed 1 Square D 100 amp subpanel in shed with 100 amp main breaker as a disconnect 1 20 amp CB in subpanel for 5 shop lights 1 20 amp GFCI CB in subpanel for receptacles 2 grounding rods 6ft apart attached to subpanel via 10 awg wire I might do one 30 amp 240v receptacle but I really do not need it right now and it will be easy to add on later if I do kind of like this diagram but with grounding rods at the shed 
I've decided to put the plug for my genny on the side of my house that is near the shed. The shed is only about 10 ft from the house, so I can still put the genny in the shed and run a short extension cord to the plug. The only question I have is wether I can use 6/3 NM and only use 1 of the hot wires and wire cap the unused hot wire ends, one in the receptacle and one in the main breaker. That way when I am able to buy a bigger genny which puts out 50 amp/240v I wouldn't have to run new wire. I would just switch out the breaker and receptacle. Genny list: 6/3 NM from my main panel to the side of my house near the shed 30 amp weatherproof receptacle 30 amp SP CB in main breaker box |
|
Quoted: Quoted: Have you considered a second meter? does your POCO charge extra each month for a second meter? any additional charge for a second meter will probably be FAR greater than the electricity usage in the shop. ar-jedi There is a base charge, yes. If you aren't pulling much power per month out there, then it won't be worth it. Depends on what you'll be doing. If you're running AC, a fridge, a TV, and regularly using power tools, it could be. But if you're mainly running a couple of lights and the occasional tool, then a run from the house is the way to go. |
|
Quoted:
AR-Jedi I have a 30 amp 120v gen would I use a SP circuit breaker or a DP? I'm thinking 30 amp SP. Genny list: 6/3 NM from my main panel to the side of my house near the shed 30 amp weatherproof receptacle 30 amp SP CB in main breaker box Not a safe way to do it. In general there are three (safe, i.e. to electrical code) ways to interconnect a generator to your household electrical system: 1) Whole-house (aka line side) transfer switch. This type of switch disconnects the power company service drop and substitutes the feed from the standby generator. This approach is generally only suitable and cost-effective for large, automated-transfer installations. The key advantage is that power is supplied to all branch circuits in the household. The generator must be sized to support the entire house power load. It also requires interaction with the power company, as the service drop will need to be disconnected and that typically means pulling the meter base. 2) Load side transfer switch. This style of transfer switch allows the generator to power pre-selected branch circuits within the house. Individual switches on the transfer panel select either utility power or generator power. These types of panels are generally inexpensive to purchase and install. The downside is that not every branch circuit will get power; so generally you select "important" branch circuits, like the refrigerator, furnace, and so on. 3) Interlock kit. Recently a new style of generator interconnect method has been introduced. Certain brands/types of main service panels accept a sliding plate mechanism called a "generator interlock". The generator feed directly connects inside the service panel on a two pole breaker at the topmost panel breaker cutout. The sliding plate mechanism allows EITHER the main breaker to be on, OR the generator feed breaker to be on, BUT not both. See attached picture. In essence this is a safe, UL-approved method of backfeeding the panel. The primary advantages of this method are that any branch circuit can receive power from the breaker, and of course purchase and installation cost are both low. The downside is that not every panel has an associated interlock kit, and moreover if the panel is currently full of breakers this also leads to complications. BUT if you are doing a new install, it makes sense to pick a service panel that has an optional generator interlock kit –– in the event that down the road you want to install a generator, it is then very straightforward. ar-jedi 
|
|
Quoted:
Quoted:
AR-Jedi I have a 30 amp 120v gen would I use a SP circuit breaker or a DP? I'm thinking 30 amp SP. Genny list: 6/3 NM from my main panel to the side of my house near the shed 30 amp weatherproof receptacle - Reliance PB30 30 amp SP CB in main breaker box - since the genny is only 120 volt capable Square D Homeline Cover Generator and QOM2 Frame Size Main Breaker Interlock Kit Not a safe way to do it. In general there are three (safe, i.e. to electrical code) ways to interconnect a generator to your household electrical system: 1) Whole-house (aka line side) transfer switch. This type of switch disconnects the power company service drop and substitutes the feed from the standby generator. This approach is generally only suitable and cost-effective for large, automated-transfer installations. The key advantage is that power is supplied to all branch circuits in the household. The generator must be sized to support the entire house power load. It also requires interaction with the power company, as the service drop will need to be disconnected and that typically means pulling the meter base. 2) Load side transfer switch. This style of transfer switch allows the generator to power pre-selected branch circuits within the house. Individual switches on the transfer panel select either utility power or generator power. These types of panels are generally inexpensive to purchase and install. The downside is that not every branch circuit will get power; so generally you select "important" branch circuits, like the refrigerator, furnace, and so on. 3) Interlock kit. Recently a new style of generator interconnect method has been introduced. Certain brands/types of main service panels accept a sliding plate mechanism called a "generator interlock". The generator feed directly connects inside the service panel on a two pole breaker at the topmost panel breaker cutout. The sliding plate mechanism allows EITHER the main breaker to be on, OR the generator feed breaker to be on, BUT not both. See attached picture. In essence this is a safe, UL-approved method of backfeeding the panel. The primary advantages of this method are that any branch circuit can receive power from the breaker, and of course purchase and installation cost are both low. The downside is that not every panel has an associated interlock kit, and moreover if the panel is currently full of breakers this also leads to complications. BUT if you are doing a new install, it makes sense to pick a service panel that has an optional generator interlock kit –– in the event that down the road you want to install a generator, it is then very straightforward. ar-jedi http://www.interlockkit.com/images/homepgKit01.jpg I forgot to add the interlock kit to my list, I'm buy the Square D Homeline Cover Generator and QOM2 Frame Size Main Breaker Interlock Kit which is square D's own interlock system. The receptacle that i am using to plug the generator in is the Reliance PB30 and the cord will be a 30-amp, 4-wire locking extension cord. Did you say my way of doing it was unsafe because I forgot to list the interlock kit or something else you saw? Thanks for answering my questions. I love your shed it makes mine look like an outhouse.
|
|
I just wanted to give a quick update in case anyone is looking to do the same project in the future. I crossposted this in a home improvement forum and a electrician was able to answer my questions. Here is what we cam up with.
Shed power 100amp 100 amp DP CB in main box 2 hots #3, 1 #4 neutral, and 1 #8 ground THHN/THWN through 1 1/4 pvc conduit from the main breaker to the shed. I can buy all black #3 wire and mark the wire ends with colored electrical tape the last 12" on either end. 1 Square D 100 amp subpanel in shed with 100 amp main breaker as a disconnect 1 20 amp CB in subpanel for 5 shop lights and 2 outdoor lights 1 20 amp GFCI CB in subpanel for receptacles 1 20 amp CB with a GFCI receptacle for a 6000 btu A/C, I can probably power the A/C off the regular receptacles but some of my power tools draw 15 amps and I just want to play it safe. 1 30 or 50 amp CB for welder––-maybe 2 grounding rods 6ft apart attached to subpanel via #6 wire 60 amp shed install 60 amp DP CB in main box 2 hots, 1 neutral #6 awg, and 1 #10 ground THHN/THWN from the main breaker through 1" pvc conduit to the shed 1 Square D 100 amp subpanel in shed with 100 amp main breaker as a disconnect 1 20 amp CB in subpanel for 5 shop lights and 2 outdoor lights 1 20 amp GFCI CB in subpanel for receptacles 1 20 amp CB with a GFCI receptacle for a 6000 btu A/C 2 grounding rods 6ft apart attached to subpanel via #6 wire |
|
Quoted: Quoted: Is there anything you see wrong with my plan? you already got the message about the 4 wire subfeed, so that is covered. a couple more things to think about: 1) while you have the trench open, put another conduit for low-voltage wiring such as a couple of lengths of CAT5/6, coax for a CCTV camera, and two-pair for an alarm loop. this way one day you can have cameras, controls, alarm contacts, etc out at the shop. i find it REALLY handy to know from the house that the shop doors and windows are closed, especially at 2am when i am laying in bed thinking whether or not i closed all the shop windows. 2) water to the shop can be REALLY handy, even if you don't have a proper drain. just the ability to hose off the tractor or what not close to the shop is handy. again, if you have the trench open, drop in a piece of black 200 psi poly –– you can always hook it up in three years and it's a hell of a lot easier than trenching again. 3) plan for some outlets and lights outside of the shop envelope, so you can work outdoors if it nice and late into the night if you need to. 4) an overhead-mounted pull-down trouble light/outlet is really handy, so be sure to put an outlet in the center of the ceiling for this purpose. 5) FINALLY, but perhaps very importantly, you may want to consider running additional wire FROM the workshop TO the house –– such that you can run a generator adjacent to the workshop and have it power the house via a transfer switch. i did this and in the end it has proven to be super useful. ar-jedi http://wopr.losdos.dyndns.org/gallery2/d/11806-1/DSCN5177.JPG http://wopr.losdos.dyndns.org/gallery2/d/12004-1/DSCN5213.JPG http://wopr.losdos.dyndns.org/gallery2/d/12612-1/DSCN5335.JPG http://wopr.losdos.dyndns.org/gallery2/d/15309-1/DSCN5400.JPG http://wopr.losdos.dyndns.org/gallery2/d/16650-1/DSCN5676.JPG http://wopr.losdos.dyndns.org/gallery2/d/15640-1/DSCN5461.JPG http://wopr.losdos.dyndns.org/gallery2/d/16490-1/DSCN5623.JPG http://wopr.losdos.dyndns.org/gallery2/d/16843-1/DSCN5681.JPG http://wopr.losdos.dyndns.org/gallery2/d/16859-1/DSCN5690.JPG http://wopr.losdos.dyndns.org/gallery2/d/24097-1/DSCN6250.JPG http://wopr.losdos.dyndns.org/gallery2/d/24112-1/DSCN6249.JPG http://wopr.losdos.dyndns.org/gallery2/d/24117-1/DSCN6238.JPG http://wopr.losdos.dyndns.org/gallery2/d/21870-1/DSCN5997.JPG http://wopr.losdos.dyndns.org/gallery2/d/21835-1/DSCN5992.JPG http://wopr.losdos.dyndns.org/gallery2/d/27351-1/DSCN6642.JPG http://wopr.losdos.dyndns.org/gallery2/d/27509-1/DSCN6667.JPG I know I've seen those pics on tractorbynet.com. |