Little League Electrical Design

[GTCAM]

Hello All,

This is an expansion of the local little league complex. We added a concession stand and field lighting. I have volunteered to help with the electrical. Please see the attached two drawings. The first is existing, the second is proposed (by me). I appreciate any comments you can give me on the design. Below are a few questions that come to mind:

1. is it ok to leave the 400A disconnect, and only upsize if I have trip problems?
2. is it ok to tie the new circuits at the 400A disconnect, and if so, is it ok to do this via adding lugs in the disconnect? Is there a better way?
3. what would the proper grounding arrangement be at the equipment building?

Thanks in advance for the help!

 

[hmspe]

1. Probably not. If you will be pulling a permit for this you will need an accurate load calculation. Just having breaker sizes is not enough. The best way to do this is to get high demand data from the utility and use that as a basis.

2. If this is outside your area of knowledge I recommend you ask either a qualified electrician or a PE who does this type of design work to look at it. Without seeing what is there all we can do is guess.

3. This is fully covered in NEC Article 250. Again, if this is outside your area of knowledge I recommend you find someone who knows local practices and requirements to help.

 

[cadpoint]

Nice project!

I will state that you should think of it as campus situation, and branch your circuits.

The tap rule comes into effect, your also adding a panel for you disconnects, but that is not with-standing the six throw rule off your 400.

Sorry wasn't going to answer any of your questions but ask my own!

Will there be any available lock box power for any fields or will that field power only be accessible from with-in the new structure? I don't like including the outside musco lighting within the frame of the "new" structure, you've already covered that NEC requirement for power. I realize there's no requirement for an outside disconnect for lighting. While it may well be that both the services are side-by side somewhere inside the structure, it should also be a consideration for traffic flow and people proof the access.

I would consider key contactors for field lighting. Lock or keep people out of any electrical service! You'll have to sale this point!

 

[Hv&Lv]

I would have to agree with the statement about getting the demand from the utility. Ask for a printout of the last 12 months kW load. Tell them what you are doing so they can look at the present setup to make sure the additional loads won't overload the XF's . We have a couple of ballfields with 50kW of lights on each field.

 

[GearMan]

Hello All,

This is an expansion of the local little league complex. We added a concession stand and field lighting. I have volunteered to help with the electrical. Please see the attached two drawings. The first is existing, the second is proposed (by me). I appreciate any comments you can give me on the design. Below are a few questions that come to mind:

1. is it ok to leave the 400A disconnect, and only upsize if I have trip problems?
2. is it ok to tie the new circuits at the 400A disconnect, and if so, is it ok to do this via adding lugs in the disconnect? Is there a better way?
3. what would the proper grounding arrangement be at the equipment building?

Thanks in advance for the help!

I'm a little confused. Your profile indicates Electrical Engineer. Why would you rely on an OCPD to do it's job without a load calculation? Proper grounding? Not sure what you need help with there. And, to void the UL listing on the 400a disconnect is probably not a good idea. You may want to consult with Casey Jones.

 

[GearMan]

I'm a little confused. Your profile indicates Electrical Engineer. Why would you rely on an OCPD to do it's job without a load calculation? Proper grounding? Not sure what you need help with there. And, to void the UL listing on the 400a disconnect is probably not a good idea. You may want to consult with Casey Jones.

OK, the Jones comment may have been out of line if this is not your area of work.
Make sure you do a load calc. Don't tap the 400a switch. Check with your utility in regards to feeding the additional 100a & 200a disconnects grouped as sub-mains directly from the 600a CT cabinet. Welcome to the forum.

 

[GTCAM]

I'm a little confused. Your profile indicates Electrical Engineer. Why would you rely on an OCPD to do it's job without a load calculation? Proper grounding? Not sure what you need help with there. And, to void the UL listing on the 400a disconnect is probably not a good idea. You may want to consult with Casey Jones.

As information, it is correct that my background is Electrical Engineering. Electrical Engineering includes specialties that include everything from digital circuit design, antenna and RF communications, control systems, computer design, and of course what I call "Power" related fields, such as what is discussed here in this forum. My specific background in Electrical Engineering is NOT power. That doesnt mean that I know nothing about power, it just means that I do NOT know every aspect of the NEC as you all do. I am very capable of learning it, and in fact I have a copy of the code. Rather than randomly surf through the code, what I feel is the most worthwhile manner to get "smarter" in this area is to get input from those that have made a career out of power and use the comments from forums such as this to direct my areas of focus in the code. I can then read the relevant areas of the code instead of taking the time to read it cover to cover. There is no substitute for experience. You guys have it, and I dont. Just looking for a little help in learning. As far as the comment posted above.....I respect your knowledge and i'm sure you occasionally provide valuable input, however, I can do without the grade-school-like comments. There are other chat rooms for things like that.

 

[GTCAM]

Follow up info

Follow up info

Something that I forgot to mention in my initial post is that the concession stand is being moved from the old location to the new, therefore, the only new load for this project is the approximately 150A associated with the field lighting. The load being picked up in the new 100A panel will be load that is being cut from the other two existing panels. From what I can tell, there is very little load, in spite of the fact that there are 200A and 150A sub panels.

I guess a key question is this:

Is the sizing of equipment based on actual load? For Example, could you hypothetically have four (4) 200A sub panels coming off of a 400A main disconnect, as long as your calulated load from the 4 sub panels does not exceed 80% of 400A? OR.....does the rating of each sub panel play a part in whether a 400A disconnect would be adequate?

 

[John120/240]

Your total load cannot exceed 400A. A favorite thing of HI is to add up all of the breaker

ratings & then say you exceed the 200A main in the homes panel.

 

[steve066]

Grounding is covered in article 240. I suggest you read that. You will need to provide grounding at the concesion stand. A concrete encased electrode (if the concession stand if it has concrete footings) may be required. Most people would also say a ground rod is required at each light.

Article 220 covers load calcualtions. You don't need to add up the breaker sizes, you add the individual loads to find the total load. The utility data won't really help unless they have a demand meter installed. Load calcs are broken into two parts: branch circuit calculations, and feeder calculations. You need to figure the loads for each branch circuit, and then add them together. Then, you calculate the total feeder load as the sum of the branch circuits, together with any of the rules and demand factors that apply to feeders. Except for any allowed demand factors, you generally assume all the loads run at once. Continuous loads (anything that runs continusouly for more than 3 hours - like ballfield lighting) are generally counted at 125% of the actual load.

Since this isn't your area of expertise, hopefully, the electrical contractor and the inspector can help make sure everything meets code.

I believe the two feeders to the concession stand might be a violation. (Maybe not if the meter and main disconnect are at the concession stand). Normally, its one feed or service per building. See articles 215 and 225.

Also, if the equipment room is remote from the concession stand, there should be a main disconnect at the concession stand.

Steve

 

[Hv&Lv]

Grounding is covered in article 240. I suggest you read that.

C'mon man....:slaphead:

 

[dbeasley488]

Little League Design

Little League Design

Hello All,

This is an expansion of the local little league complex. We added a concession stand and field lighting. I have volunteered to help with the electrical. Please see the attached two drawings. The first is existing, the second is proposed (by me). I appreciate any comments you can give me on the design. Below are a few questions that come to mind:

1. is it ok to leave the 400A disconnect, and only upsize if I have trip problems?
2. is it ok to tie the new circuits at the 400A disconnect, and if so, is it ok to do this via adding lugs in the disconnect? Is there a better way?
3. what would the proper grounding arrangement be at the equipment building?

Thanks in advance for the help!

It's best you have a PE with E&O insurance to review or help with your calculations and stamp the drawing when you're done. It's my experience that the most trouble comes when you "volunteer".

 

[steve66]

C'mon man....:slaphead:

I'm not sure if that was a typo, or if my brain was just in the wrong spot

Article 250 is grounding. Too many requirements to try and cover in a post. If you aren't familiar with the requirements, you will need to go through the whole section.

 

[GTCAM]

Grounding is covered in article 240. I suggest you read that. You will need to provide grounding at the concesion stand. A concrete encased electrode (if the concession stand if it has concrete footings) may be required. Most people would also say a ground rod is required at each light.

Article 220 covers load calcualtions. You don't need to add up the breaker sizes, you add the individual loads to find the total load. The utility data won't really help unless they have a demand meter installed. Load calcs are broken into two parts: branch circuit calculations, and feeder calculations. You need to figure the loads for each branch circuit, and then add them together. Then, you calculate the total feeder load as the sum of the branch circuits, together with any of the rules and demand factors that apply to feeders. Except for any allowed demand factors, you generally assume all the loads run at once. Continuous loads (anything that runs continusouly for more than 3 hours - like ballfield lighting) are generally counted at 125% of the actual load.

Since this isn't your area of expertise, hopefully, the electrical contractor and the inspector can help make sure everything meets code.

I believe the two feeders to the concession stand might be a violation. (Maybe not if the meter and main disconnect are at the concession stand). Normally, its one feed or service per building. See articles 215 and 225.

Also, if the equipment room is remote from the concession stand, there should be a main disconnect at the concession stand.

Steve

Steve,
A couple questions about your post:

I thought the 2 panels at the concession stand would be sub panels. If thats the case, why would they need grounding, and why would they need main disconnects? I thought sub-panels did not need either of these? Also, are you not allowed to have 2 subpanels in the same building?

 

[ElectDesigner]

Hi GTCAM,

It is quite hard to help you without knowing the existing load but let me see if I can help, so I quickly went over your proposed plan, and here are my thoughts,

1. Design: Im not sure why you feed the two new fused disconnects off the 400A fused disconnect, If I were to do this (and based on most of the design's i have seen) I would connect both of the new disc. sw to the trough - this just seem like better practice.

2. Load: Like someone suggested it is always good getting load data from the utility - if possible. Based on what I have read and assuming what you are saying is correct the only load that will be remaining on the existing Panel/Load Center will be those branch circuits (do you know what kind of loads these are? hvac/ltg/receptacle?). I would start by calculating these loads - if possible? What is the area (sq. footage) of the facility serviced by these branch circuit? Also the sq. footage of new conc. bldg? What is the main bus rating of the panel/load center?

One thing you should keep in mind is a lot of designers/engineers design with expansion in mind so if for e.g. you freed up say a 200A breaker does not necessarily mean that you now have a 200A service at your disposal. Most of the time they oversize.

You could also look at it this way from a load perspective:
Old New
----- -------
200A Panel 200A Lighting Sub panel
150A Panel 100A Sub Panel

by this logic the expansion should be fine, BUT we dont know the Loads and hence cannot assume.

3. Conclusion: Doing a thorough load calculation is the recommended way to go, it could really help if you could obtain the drawings for the existing building - this makes it much easier to see what loads are connected. Ask the landlords for the dwgs - if possible.

Usually from a design perspective it is always good to consult with a PE. Also check with the code and local electrical inspector there may be some other aspects that I failed to mention.

I know I havent really answered much but hope this helps.

 

[steve66]

Steve,
A couple questions about your post:

I thought the 2 panels at the concession stand would be sub panels. If thats the case, why would they need grounding, and why would they need main disconnects? I thought sub-panels did not need either of these? Also, are you not allowed to have 2 subpanels in the same building?

When you said you were adding a concession stand to a complex, I was assuming the main service is on a separate pole or in another building.

If it's all at the same building, then you are right.

 

[rrc14]

I would check and see if the 400A disconnect is actually fused at 400A. If it is the disconnect rating may need to be increased to accomodate the addtional loads. A load study is really needed.

 

[GTCAM]

When you said you were adding a concession stand to a complex, I was assuming the main service is on a separate pole or in another building.

If it's all at the same building, then you are right.

Steve,
It is a separate Concession stand building. the 400A disconnect as well as the meter are at a storage/garage area that is about 100 feet away from the new concession stand building

 

[Cow]

Without reading any of the replies and just glancing at the before/after pics I'd tear everything out except the existing 200 amp panel. Install a CT can with 800 amp perch, refeed 200 amp panel directly, no trough, as well as the new 200 and 100 amp disconnects. So 3 service disconnects total, all grouped. That existing 400 amp disconnect/trough aren't doing anything but taking up space.

Whoops, I glanced a little too fast at your pics. It looks like you have two feeders to the same concession building, that's a no no. Keep the 400 amp disconnect, run one large 300? amp feeder to a 400 amp panel in the concession stand and feed all your loads out of there. Or use a trough and the tap rule and feed your 100 amp and 200 amp panels in the concession stand from the big feeder.

 

[steve66]

Steve,
It is a separate Concession stand building. the 400A disconnect as well as the meter are at a storage/garage area that is about 100 feet away from the new concession stand building

Then what I said in my first post does apply.

You have to provide grounding electrode system at each structure or building.

And each structure or building should have a single supply (one service or feeder) with a disconnect at the building or structure. (Technically, the disconnect can be up to 6 individual breakers, but all from the same feeder. For your project, its easier to just have a single disconnect.)

So run a single feed to the new concession stand to a main breaker panel. Provide a grounding system (you don't rebond the neutral and ground, though), and subfeed the lighting panel from the concession stand panel.

I would suggest you consult an engineer that specializes in doing NEC type work. Having separate buildings and lights isn't the simplest of installations.