Code Requirements For Sub Panel Feed andPanel

[Jawgarage]

Ok...finally have this figured out in terms of what I'm working with for a 32x50 two story detached garage. I do need to finalize two things though and need some guidance on the code:

Details: detached garage fed by a 100amp breaker off a 200amp main house service panel. Detached garage will need six 15amp 240v breakers, two 30amp 240v breakers, five 15amp lighting ckts, and seven 20amp ckts for outlets. The 15 amp 240v ckts will be for seasonal use and the 30amp 240v ckts for occasional non continuous use. I will switch off any 240v loads as needed when using the 30amp ckts.

Questions:

1. What type and size main feed wire do I need to run from the house sub panel to the new garage sub panel that is a 65'-75' run underground?

2. Should I run the feed wire in some kind of conduit?

3. How deep do I need to bury the feed wire and/or conduit?

4. What size/type sub panel is needed in the garage?

5. Do I need to run a bare copper grounding wire to a copper grounding rod outside the detached garage?

Thanks guys!

 

[pattenp]

Not getting into whether or not 100A is what you need.

1. What type and size main feed wire do I need to run from the house sub panel to the new garage sub panel that is a 65'-75' run underground?

At least #1 Al or #3 Cu for the 2 hots and 1 neutral and a #6 Al or #8 Cu for the EGC.

2. Should I run the feed wire in some kind of conduit?

Single conductors need to be in conduit unless rated for direct bury. Inside the structure they have to be in conduit. This is more of a complicated area where you may need to use more than one type wire based on how the install needs to be done.

3. How deep do I need to bury the feed wire and/or conduit?

Minimum of 18" of cover.

4. What size/type sub panel is needed in the garage?

For all those circuits I'd use at least a 40 space main breaker panel.

5. Do I need to run a bare copper grounding wire to a copper grounding rod outside the detached garage?

Yes you need an electrode system. If no ufer ground then 2 rods 6ft. apart on #6 bare copper.

 

[Jawgarage]

Not getting into whether or not 100A is what you need.

Let me ask something I just figured cant be done, but why not ask the pro's before I miss something even better......

The property has underground power running the 600' from the street to that "big green box thing" sitting on my back lawn. The main feed for the homes meter mounted on the house runs from that "big green box thing" underground about 85'. Obviously, from the outside Power Company meter the main panel in the house is fed and that's where I am planning on pulling the 100amp sub panel feed from (the old garage feed was only 60amp with a 3 wire #10 underground copper feed - - that has been cut out for the new construction and is no longer in service)

QUESTION:

Is it out of the question to ask the Power Company to run a second main feed line from that "big green box thing" to the new detached garage which is only 20' away? That way I can have more than the 100amp service?

Does this create new problems?
Is this not to code?
I imagine this would need a new/second meter just for the garage?
Would this open up that "can of worms" for which there is no need?
Can I run a bigger panel in the garage off of the 200amp main in the house?

Thanks.......

 

[ard]

To clarify- it is 65-70 from panel to panel, right? Not 65 feet between building, then anothjer 45 feet of wiring inside each... just asking....

I really like PVC conduit, as large as reasonable. Like if 1.5" is OK for the wire I am running, I put in 2". It also means I can drop in the conduits during rough excavation, pour concrete, do all the building and then pull wire when it is ready for wire.

Agree with the other comments from pattenp.

 

[ard]

Let me ask something I just figured cant be done, but why not ask the pro's before I miss something even better......

The property has underground power running the 600' from the street to that "big green box thing" sitting on my back lawn. The main feed for the homes meter mounted on the house runs from that "big green box thing" underground about 85'. Obviously, from the outside Power Company meter the main panel in the house is fed and that's where I am planning on pulling the 100amp sub panel feed from (the old garage feed was only 60amp with a 3 wire #10 underground copper feed - - that has been cut out for the new construction and is no longer in service)

QUESTION:

Is it out of the question to ask the Power Company to run a second main feed line from that "big green box thing" to the new detached garage which is only 20' away? That way I can have more than the 100amp service?

Does this create new problems?
Is this not to code?
I imagine this would need a new/second meter just for the garage?
Would this open up that "can of worms" for which there is no need?
Can I run a bigger panel in the garage off of the 200amp main in the house?

Thanks.......

Good question. It depends on you PoCo. Where I am in CA they will NOT run a second residential meter on one lot. Second meter is commerical or farm, and the allowances yoiu get with a residence are reduced. So you need to ask them.

 

[Jawgarage]

To clarify- it is 65-70 from panel to panel, right? Not 65 feet between building, then anothjer 45 feet of wiring inside each... just asking....

QUOTE]

That will be correct. When the new building is up I am not placing the new sub panel where the old one was in the old detached garage which was about 40' further away. When the new building is up I am locating the new panel at the nearest corner to the main panel in the main house. Total run of that main feed will be roughly 65'-75' between panel and sub-panel.

I like the idea of running a 2" PVC (schd 40) 18" underground and even leaving a "pull wire" inside of it to get the main feed through it when ready. Any issue dropping a second 2" PVC conduit in the same trench for future use say for alarm wire? Security Camera (cctv) cable? Others? I'd rather dig the trench once and perhaps throw away a few dollars by putting another conduit or two in the hole that I may never use.

 

[pattenp]

You'll need to check with you PoCo about a second meter. I think the best option is to have the PoCo upgrade the current 200A to 400A and use a meter with dual lugs and run a second 200A feed to the new garage. You will need to do load calculations to show that you need 200A to the garage. Your existing panel may only allow up to a 125A breaker to be used as a branch circuit. That info will be listed in the panel on the data sheet.

 

[Zeke]

You should keep the 2nd conduit for any data wires 6 to 12" away and that includes most CCTV stuff unless you run coax. The problem with long parallel runs is that the line voltage will be induced to the un-shielded wires when in close proximity. And there is a magnetic field related to low voltage wires that will be disrupted. You will have 'noise' on your wires. This applies to the wires after entering the building as well.

But, you asked about "code" so the code says 2" last I knew.

 

[04chase]

It would be better for them to pull in larger wire to feed your main tha to run a 2nd feed. I was fortunate enough to have big enough feed when i recently did a 100a main uograde to a 200a (edison allowed me to do it live so i could avoid 3+ day down time) i had 130 feet of 2" conduit (grey pvc with 270° of bend ) do not exceed that imo and run larger conduit than necessary. I ran 3× #1 cable and a #6 egc. This was good for up to 125 amp. Which will be nearly used at times (a/c, big welders, and 7.5 hp compressor plus alot)

Im also running a second 100 amp panel about 50 ft from the main that will be strictly for my plasma table which will be use dam near that for amps. For that i will be good with #2.

I had planned on using the plasma table off the shop panel but it would be overloaded . Also the mess a plasma table makes in a shop is not ideal for me. So i got a metal shed kit and purposed it solely for the cnc. The compressor and cutter can be run simultaneously without worry now.

Always over build when doing electrical in my opinion.never exceed 360 of bends in one pull. Oversized conduit for longer runs makes life alot easier as well as lube . If you consider running any other power in the area of where yoir conduit is headed . Do it now and avoid trenching again. I ran the 2" for the shop , as well as an addition 1.5", 1" and 3/4". One ive already purposed for low voltage cable (cat 5 and coax for wifi,cable and cameras down the road)

 

[Jawgarage]

I was able to do some investigating online about the second meter and it is a "NO GO" for a residential property as the previous reply thought might be the case.

Much appreciated about the details on how much to separate the conduits underground too.

So my remaining question is still regarding what feeder cable to use to run the 65'-75' underground within the PVC conduit to supply the 100amp subpanel in the garage from my 200amp service within the house? If not SER cable than what kind and what sizing based on the earlier specifications I gave about the size and number of breakers. I was looking for 2-2-1-4 AL MHF but can't find it. I'd rather use something rated for more than skimp here on something just good enough if you know what I mean.

Thanks

 

[theoldwizard1]

For quick reference

View media item 33304

So my remaining question is still regarding what feeder cable to use to run the 65'-75' underground within the PVC conduit to supply the 100amp subpanel in the garage from my 200amp service within the house? If not SER cable than what kind and what sizing based on the earlier specifications I gave about the size and number of breakers. I was looking for 2-2-1-4 AL MHF but can't find it. I'd rather use something rated for more than skimp here on something just good enough if you know what I mean.

Thanks

Just because you have a sub-panel rated at 100A doe NOT mean that you have to feed it with a 100A breaker and cable rated for 100A. Use a 90A breaker in the main panel and use 2-2-2-4 MHF. MHF can be direct burial, but it must be in conduit anywhere above ground.

 

[wyliesdiesels]

I was able to do some investigating online about the second meter and it is a "NO GO" for a residential property as the previous reply thought might be the case.

Much appreciated about the details on how much to separate the conduits underground too.

So my remaining question is still regarding what feeder cable to use to run the 65'-75' underground within the PVC conduit to supply the 100amp subpanel in the garage from my 200amp service within the house? If not SER cable than what kind and what sizing based on the earlier specifications I gave about the size and number of breakers. I was looking for 2-2-1-4 AL MHF but can't find it. I'd rather use something rated for more than skimp here on something just good enough if you know what I mean.

Thanks

Have u done load calcs?

Is this anone man shop?

U havent listed your loads only listed breaker sizes.

Any motor loads such as air compressor or air conditioning?

How about heat?

Most people think they need way more than they actually need.

The standard practice most often used with the length u have is to run #2 Al MHF. 2" PVC is perfect for it. Max breaker size is 90a.

In the subpanel u will need a main breaker as well as an isolated neutral bar(remove green bonding screw)which usually means purchasing a seperate ground bar kit unless panel already came with it from the factory.

 

[Crazyjake8493]

Just because you have a sub-panel rated at 100A doe NOT mean that you have to feed it with a 100A breaker and cable rated for 100A. Use a 90A breaker in the main panel and use 2-2-2-4 MHF. MHF can be direct burial, but it must be in conduit anywhere above ground.

This is what I would do. My garage setup was very similar, same distance as well. 2-2-2-4 MHF in 2" PVC conduit at least 18" deep. I ran conduit all the way for peace of mind. MHF must be in conduit inside the structure, as mentioned. I used a 20 space/40 circuit main breaker panel for my subpanel, although I fed it from only a 60-amp breaker in my main panel in the house, since I already had a 60-amp on hand. I could go as high as 90 if I need to, but working alone I don't ever see having a problem with 60. You definitely want a main breaker panel.

 

[Jawgarage]

Thanks everyone. I will research panel and wire suppliers today. Three more easy questions:

1. What are the code requirements for the location of the sub panel within the garage in terms of height off the floor and proximity to windows and doors?

2. Should the underground conduit for the MHF be Schd 40 PVC or something else?

3. When laying the conduit for the main feed is it OK/code to cross and run underneath an underground irrigation pipe/hose that is burried at 12" down?

Thanks again.

 

[theoldwizard1]

2. Should the underground conduit for the MHF be Schd 40 PVC or something else?

Where your conduit transitions from under ground to above ground, you should use Schedule 80 or metal conduit. String trimmers can break Schedule 40 PVC conduit.

 

[Jawgarage]

Thanks everyone. I will research panel and wire suppliers today. Three more easy questions:

1. What are the code requirements for the location of the sub panel within the garage in terms of height off the floor and proximity to windows and doors?

2. Should the underground conduit for the MHF be Schd 40 PVC or something else?

3. When laying the conduit for the main feed is it OK/code to cross and run underneath an underground irrigation pipe/hose that is burried at 12" down?

Thanks again.

Thanks "wizard" for the answer on the conduit type.

Anybody out there that can help me with question 1 & 3 also?

 

[pattenp]

1.

Panel does not need to be in the center of the 2' 4" width. So you can put it by a window or door as long as you have the required space in front of the panel to stand and access the panel. Highest breaker handle is not to be over 6' 7" high when in its highest position.

3. No problem with irrigation lines crossing above the feeder.

 

[NUTTSGT]

Thanks everyone. I will research panel and wire suppliers today. . . . .
Thanks again.

Something to keep in mind with the panel. I'd try to stay with the same brand/style as what you already have in the house. In case something (emergency) ever happens at an odd time, a breaker from the garage can be swapped to the house or vice versa.

 

[Jawgarage]

EXCELLENT on all fronts. Thanks guys now I am all set on panel placement and how/what/where in regards to running the feed line from the main house to the garage.

Still see lots of debate on the type/size of the feed to use so I am going to go with the higher recommendations since I don't want to redo this again. 2-2-2-4 MHF I think is what I saw for a 100amp sub panel 75' underground between panels in PVC conduit.

Sound good?

 

[sands35]

On my detached, I got dinged for not having an inter-system ground bonding block. Suckers are about $10.

It supposed to be used for grounding satellite dishes and TV antennas.

 

[pattenp]

The feeding breaker for 2-2-2-4 MHF is to be no more than 90A. The sub main breaker can be 100A.