Wiring Shop by running underground feeder about 150ft. from panel in house

[joefbeams]

I plan to wire new 30ft X 34ft shop by running UG feeder from new home which is located about 150ft. from shop. The main in home is about 70ft further after uf would reach house. What size UF feeder is needed to connect to a 60 amp. panel in shop. Thanks---This is my first post and I look forward to participating. joefbeams

 

[OldmanB]

I did this for my shop 20 years ago, and can't remember for the life of me what we used, but do remember we used larger then we actually needed as I was told you will lose some power of the length, (we went 175'). We also ran water down as well.
Brian

 

[pattenp]

To keep the voltage drop less than 3% over the 220 feet I suggest at a minimum #1 AL or #3 Cu for 60A.

 

[Speedy Petey]

To keep the voltage drop less than 3% over the 220 feet I suggest at a minimum #1 AL or #3 Cu for 60A.

What are you basing this on? We don't even know the load?

A 30 load would require only #6cu and a 40A load would require #4cu.
A 60A sub-panel in a residential shop will rarely see over 40A for any appreciable length of time. Unless of course a stick welder is brought in.

Besides, the 3% number is only a suggestion in the code, and is overrated IMO.

 

[nmk_61802]

What are you basing this on? We don't even know the load?

A 30 load would require only #6cu and a 40A load would require #4cu.
A 60A sub-panel in a residential shop will rarely see over 40A for any appreciable length of time. Unless of course a stick welder is brought in.

Besides, the 3% number is only a suggestion in the code, and is overrated IMO.

No electrician here, but 60A is 60A. (Noting that you do gain some due to the different charts used for an accessory building vs a primary) Unless he is placing a smaller breaker at the main in the house, which I don't believe he mentioned.

 

[pattenp]

To provide 60A at the end of the run. I used the Southwire voltage drop calculator. Besides it was my suggestion based on that info.

What are you basing this on? We don't even know the load?

A 30 load would require only #6cu and a 40A load would require #4cu.
A 60A sub-panel in a residential shop will rarely see over 40A for any appreciable length of time. Unless of course a stick welder is brought in.

Besides, the 3% number is only a suggestion in the code, and is overrated IMO.

 

[matt151617]

Did you price out what it would cost to run indivdual conductors in conduit? It's probably cheaper. And it allows room for upgrade, and you don't have to worry about digging up or a line getting damaged.

 

[PRH44]

I vote for conduit.

 

[sberry]

They sell a quad number 2 2 2 4 at most box stores, either direct burial or piped but its ideal for these garage feeds.

A 30 load would require only #6cu and a 40A load would require #4cu.
A 60A sub-panel in a residential shop will rarely see over 40A for any appreciable length of time. Unless of course a stick welder is brought in.

Besides, the 3% number is only a suggestion in the code, and is overrated IMO.

I got to agree with this, over last 30 yrs I must have done a couple dozen of these, have some feeds to my own buildings with number 2 alum, never, never had a cal back because of tripping a 60 including a bud who has a small garage he makes a living out of. I use a 60A breaker cause its cheap, fits the wires. Only reason a guy would need more,,, was a specialized shop providing heavy air demands and simultaneous 50A welding service, and now days with small welding equipment even less of an issue.

As the man said,,, all this V drop stuff is about moot, only an issue when at full load, a number 2 alum wire peaks at half load max in a residential garage for intermittent times, voltage is good most places, so what if there is 5 drop for a split second when the air comp comes on, ain't worth worrying about.

 

[joefbeams]

Our electrical supplier suggested stranded conductors in 1.25 inch conduit would be the most economical using two #6 cu.; 1 # 8 neutral, and 1 #10 Grd. protected at the main in the house with a 70 amp breaker terminating at a 125 amp load center in the shop. These materials will cost about $3.03 per foot. --- joefbeams

 

[sberry]

I have 250 ft of number 2 al to my house, all gas appliances, kitchen counter tops on a multiwire circuit, fridge on one leg and any aux like a window unit on occasion or small electric heater on the other, 95% of the time a couple amps with a peak of about 20 out of about 50 available at 3% or so, about 120V under 10A load, ha

 

[sberry]

I know a couple guys that have home garages worked years with 30A service, just didnt weld while the air comp was on, nver had a problem. Painted, about everything you could do to a car with a few lights on.

 

[Falcon67]

Our electrical supplier suggested stranded conductors in 1.25 inch conduit would be the most economical using two #6 cu.; 1 # 8 neutral, and 1 #10 Grd. protected at the main in the house with a 70 amp breaker terminating at a 125 amp load center in the shop. These materials will cost about $3.03 per foot. --- joefbeams

I ran 2-2-2-4 AL from HD, $1.47/ft. It's now $1.69 I think. Ran it in 2" conduit. Total run was right at 100' and it's fused at 70A.

 

[pattenp]

I found when running power to my detached garage that using 2-2-2-4 AL MHF in 2" PVC conduit was the most economical. The wire was quite a bit cheaper at the local electrical supply house than at my local HD or Lowes.

 

[Speedy Petey]

No electrician here, but 60A is 60A. (Noting that you do gain some due to the different charts used for an accessory building vs a primary) Unless he is placing a smaller breaker at the main in the house, which I don't believe he mentioned.

I don't get this. 60A is simply the feeder size. That has NOTHING to do with the actual load.
You do not figure voltage drop according to the feeder size.

 

[matt151617]

I second what pattenp says. The local electrical supply store was far cheaper than Lowes or Home Depot, and they had better selection. They also sold more connectors along with shrink wrap and the good 33+ electrical tape (once you use this stuff you'll never use regular garbage tape again).

I ran #6 AL triplex (URD) with a separate AL ground wire (they didn't have quadplex). All that triplex or quadplex is is 3 or 4 THWN wires wrapped twisted together. The triplex was $.64/ft, and the extra THWN wire was $.29/ft. I ran all of this in 1.5" conduit. I also transitioned to SER cable once entering the house going back to the panel.

You may want to run #2 to compensate for voltage drop and be sure you have enough juice. #6 AL is only good for 50 amps.

 

[nmk_61802]

I don't get this. 60A is simply the feeder size. That has NOTHING to do with the actual load.
You do not figure voltage drop according to the feeder size.

Poster asked about a 60 amp (sub) panel. I may be reaching here, but that should come with a 60 main breaker installed, the logic would be to install a matching 60 amp breaker in the main. This would dictate that the (sub) feeder would be capable of a future load of up to 60 amp and should be sized as thus.

The only way I would see it being different would be if the original poster wished to install a smaller breaker in the main limiting the current thru the (sub) feeder, which seems counterintutive.

Again not an electrician, but seems like simple logic.

 

[sberry]

Most panels are 100A, yolu can feed it with any breaker,

 

[nmk_61802]

Most panels are 100A, yolu can feed it with any breaker,

I understand that hence my reply.

The only way I would see it being different would be if the original poster wished to install a smaller breaker in the main limiting the current thru the (sub) feeder, which seems counterintutive.

Again, why would you do this, unless you needed the additional breakers the larger panel provided. Why not size breaker at the Main, Subfeeder and the Subpanel main all at 60A, and be done. Seems like overthinking to do otherwise.

Again, this does that make the assumption that when asking about a 60A Sub, it is assumed that the poster means a Subpanel with a 60A main breaker already installed or included.

 

[pattenp]

Joe, I don’t where you are but if you can get 2-2-2-4 Al Mobile Home Feeder cable you’ll be good to go for 60A at 220’, the voltage drop will be a non-issue. Place it in a minimum of 1.5” conduit (recommend 2”). Get yourself a 100A main-breaker panel with at least 20 spaces for your shop.

 

[pattenp]

100A main breaker panels are very abundant and cheap. I can't say a 60A main breaker panel is something you can easily find.

I understand that hence my reply.



Again, why would you do this, unless you needed the additional breakers the larger panel provided. Why not size breaker at the Main, Subfeeder and the Subpanel main all at 60A, and be done. Seems like overthinking to do otherwise.

Again, this does that make the assumption that when asking about a 60A Sub, it is assumed that the poster means a Subpanel with a 60A main breaker already installed or included.

 

[joefbeams]

Thanks for all of the suggestions. It has been very helpful. Joefbeams

 

[matt151617]

The main breaker is nothing more than a shut-off on a subpanel. The real current protection comes from the breaker in the main panel feeding the subpanel.

Home Depot has a nice Square D 100 amp panel with a main breaker and 5 20 amp breakers included for $43.

 

[Speedy Petey]

Poster asked about a 60 amp (sub) panel. I may be reaching here, but that should come with a 60 main breaker installed, the logic would be to install a matching 60 amp breaker in the main. This would dictate that the (sub) feeder would be capable of a future load of up to 60 amp and should be sized as thus.

The only way I would see it being different would be if the original poster wished to install a smaller breaker in the main limiting the current thru the (sub) feeder, which seems counterintutive.

Again not an electrician, but seems like simple logic.

It may seem like common logic, but it's not how it works.

Just because it is a 60A feeder does not mean you would use the full 60A when figuring voltage drop.

 

[joefbeams]

In checking with a local supplier about 2 2 2 4Al who had none, He suggested using #2, 3 wire URD Al which could be buried directly costing $1.30 Ft.. has anyone had experience using URD buried directly? Thanks---joefbeams

 

[Speedy Petey]

In checking with a local supplier about 2 2 2 4Al who had none, He suggested using #2, 3 wire URD Al which could be buried directly costing $1.30 Ft.. has anyone had experience using URD buried directly? Thanks---joefbeams

#2URD is not enough. You need a fourth wire. Look for #2AL mobile home feeder cable like patt said. Typically this is 2-2-4-6, with a green ground conductor.

Also, NO WAY I'd go direct burial. PVC is cheap and easy to use. No reason any more to go direct burial, even in the cleanest soils.

 

[pattenp]

If you can't find 2-2-2-4 or 2-2-4-6 Al MHF see if you can get 2-2-2-4 quad urd. The MHF (mobile home feeder) and URD are pre-assembled cable. You could pull four strands of AL thhn/thwn wire.

Definitely put it in conduit.

 

[matt151617]

In checking with a local supplier about 2 2 2 4Al who had none, He suggested using #2, 3 wire URD Al which could be buried directly costing $1.30 Ft.. has anyone had experience using URD buried directly? Thanks---joefbeams

I ran into the same issue... no mobile home feeder available. I used 3 wire URD and they sold me a separate AL THWN wire for the ground. Bury it in conduit... 1.5" should be fine and easy enough with lube.

 

[raddksn]

pvc conduit 1-1/4" min. you will soon wish you had more then 60 Amps

 

[pattenp]

If using 2-2-2-4 Mobile Home Feeder or Quad URD the wire type is usually RHW / RHW-2 and I would never attempt to pull it through 1 1/4' conduit. The max fill for RHW #2 is 3 conductors in 1 1/4" PVC conduit. In my humble opinion 60A is plenty for the typical DIY'er garage/shop,

Edit: Four #2 THHN/THWN is ok in 1 1/4" PVC. My point is one size doesn't fit all. Plus it's better to not use the minimum.

pvc conduit 1-1/4" min. you will soon wish you had more then 60 Amps

 

[scutty83]

I just did exactly what you are talking about-150 run and wanted 75amps at the panel in the shop, bought a cutler hammer 100 amp box with main breaker and came with 5 20 amp breakers, and a double pole 30 amp breaker for $50 at lowes. (#2 is technically not rated for 100a @150ft) I used the 100a breaker at the elec pole and bought a 75a in for the garage panel. I used 2-2-4 that I bought for $1.05/foot and used 2" conduit. Price difference was minimal for 2" vs 1.25" and well worth it when pulling through end sweeps.
I recommend buying about 10' more feet of wire then what you think you actually need dont forget to consider the length of running up walls and the extra depth of the trench and "looping" your wire around the inside of your box to avoid sharp bends and keeping your panel tidy. Dont forget to bury your ground rod for your panel when you have the trench open. Elec supply co recommended #6 bare ground for bonding.
BTW my disclaimer is I am not a professional electrician and we do not have any code in my county but I do try to do the work as if we did. Some people may tell you you need to add a 4th wire for a neutral to bond your two panels together. I asked my elec co engineer about this and he said it was'nt necessary.

 

[Alchymist]

I just did exactly what you are talking about-150 run and wanted 75amps at the panel in the shop, bought a cutler hammer 100 amp box with main breaker and came with 5 20 amp breakers, and a double pole 30 amp breaker for $50 at lowes. (#2 is technically not rated for 100a @150ft) I used the 100a breaker at the elec pole and bought a 75a in for the garage panel. I used 2-2-4 that I bought for $1.05/foot and used 2" conduit. Price difference was minimal for 2" vs 1.25" and well worth it when pulling through end sweeps.
I recommend buying about 10' more feet of wire then what you think you actually need dont forget to consider the length of running up walls and the extra depth of the trench and "looping" your wire around the inside of your box to avoid sharp bends and keeping your panel tidy. Dont forget to bury your ground rod for your panel when you have the trench open. Elec supply co recommended #6 bare ground for bonding.
BTW my disclaimer is I am not a professional electrician and we do not have any code in my county but I do try to do the work as if we did. Some people may tell you you need to add a 4th wire for a neutral to bond your two panels together. I asked my elec co engineer about this and he said it was'nt necessary.

Well, you didn't do it "as if we did". Latest NEC requires 4 wire feed - and that 4th wire is an ECG, not a neutral. So what did you attach your ground rod to in the sub panel? If to the neutral, another violation. Just sayin....

 

[pattenp]

The county may not require permits nor inspections for electrical but I'm willing to bet you still need to have the work done to meet code. I bet if your house or shop burned down due to improper wiring the insurance company is going to start citing national code.

 

[Falcon67]

The main breaker is nothing more than a shut-off on a subpanel. The real current protection comes from the breaker in the main panel feeding the subpanel.

Home Depot has a nice Square D 100 amp panel with a main breaker and 5 20 amp breakers included for $43.

This is what I have - nice panel.

FWIW - the guy across the street works for a big national electrical supply local outlet. When I asked him about the 2-2-2-4 and what I could get it for at HD, he said "buy it, I can't get it that cheap". And they didn't stock it. So YMMV with the supply house.

 

[Speedy Petey]

I just did exactly what you are talking about-150 run and wanted 75amps at the panel in the shop, bought a cutler hammer 100 amp box with main breaker and came with 5 20 amp breakers, and a double pole 30 amp breaker for $50 at lowes. (#2 is technically not rated for 100a @150ft) I used the 100a breaker at the elec pole and bought a 75a in for the garage panel. I used 2-2-4 that I bought for $1.05/foot and used 2" conduit. Price difference was minimal for 2" vs 1.25" and well worth it when pulling through end sweeps.
I recommend buying about 10' more feet of wire then what you think you actually need dont forget to consider the length of running up walls and the extra depth of the trench and "looping" your wire around the inside of your box to avoid sharp bends and keeping your panel tidy. Dont forget to bury your ground rod for your panel when you have the trench open. Elec supply co recommended #6 bare ground for bonding.
BTW my disclaimer is I am not a professional electrician and we do not have any code in my county but I do try to do the work as if we did. Some people may tell you you need to add a 4th wire for a neutral to bond your two panels together. I asked my elec co engineer about this and he said it was'nt necessary.

Posts like this scare me.
Obviously you are not an electrician, and neither was the "engineer" you spoke to, or he would have told you you need a four wire feeder. This code has been in effect for at least several years now.
Folks need to know what they are doing BEFORE they do things. And I am sure you DO have some sort of code in effect in your area. I DO NOT buy the whole "we don't have codes here" malarkey.

I also have NO idea what you mean by the bold part above.

 

[Fred43]

Joe,
I suggest that you talk to someone that knows about wire size capacities. A #6 Copper is good for fifty (50) amps. Using the derating for length that would make it forty amps (40). A 4 circuit panel comes in 70 to 125 amp ratings. In a shop you will want something larger to separate the heavier use equip from the convenience recepticals and lighting. I would use at least a #4 CU or a #3 AL cable, in PVC unless there are a lot of bends. I would also over size the pipe to 1.5 inches for ease of pulling and for future expansion.

 

[Fred43]

Scutt83,
The 4th wire is not necessary if you DRIVE the 8' x 5/8" ground rod into solid ground. You should not lay it at the bottom of the trench in soft dirt. A protected #8 ground wire is accepted by code but I always used a #6 CU with brass clamps. The ground is very the most important wire in an electrical system. Dont forget GFCI's in the garage if it on residential property.

The engineer just might have a point. Out buildings may derive their own grounds BUT they may not be attached to the neutral wire. The Neutral and the ground can only come together at the first overload position on the property or meter socket if there is a breaker in the socket.

 

[Fred43]

Joe,
I suggest that you talk to someone that knows about wire size capacities. A #6 Copper is good for fifty (50) amps. Using the derating for length that would make it forty amps (40). A 4 circuit panel comes in 70 to 125 amp ratings. In a shop you will want something larger to separate the heaverier use equip from the convenience recepticals and lighting. I would use at least a #4 CU or a #3 AL cable, in PVC unless there are a lot of bends. I would also over size the pipe to 1.5 inches for ease of pulling and for future expansion.

 

[Charles (in GA)]

Under current codes and the last couple of code cycles, the only way you can NOT have a 4 wire system to a detached building is if there are NO OTHER metallic connections between that building and the building the feed comes from. Add a phone wire, a internet wire, a intercomm wire for the wife to call you, and you have just violated the rule. Its virtually impossible to do an installation without 4 wire, and stay legal.

Charles

 

[Speedy Petey]

Scutt83,
The 4th wire is not necessary if you DRIVE the 8' x 5/8" ground rod into solid ground. You should not lay it at the bottom of the trench in soft dirt. A protected #8 ground wire is accepted by code but I always used a #6 CU with brass clamps. The ground is very the most important wire in an electrical system. Dont forget GFCI's in the garage if it on residential property.

The engineer just might have a point. Out buildings may derive their own grounds BUT they may not be attached to the neutral wire. The Neutral and the ground can only come together at the first overload position on the property or meter socket if there is a breaker in the socket.

I'm sorry, but this is COMPLETELY wrong.

A ground rod does NOT derive a ground such as an equipment ground. A grounding electrode has NOTHING to do with the equipment ground in so far as clearing faults or tripping breakers.

A grounding electrode was always required at a detached structure served by a feeder, regardless if it was an older (allowable under certain circumstances) 3-wire feeder or the typical 4-wire feeder. Again, this feeder had NO relationship to the grounding electrode.