Direct buried, fence, one feeder and height questions residential

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hhsting

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I know I had some variation of below question prior but design has change a little and I am not sure about few items NEC 2014 code wise.

Please see attached sketches which show cluster of apartment residential one is Top view and second is Elevation view. The cluster has individual buildings 1 to 6 separated by firewall. Their is outside utility transformer which feed outside service entrance rated switchboard.

The service entrance rated switchboard is three phase, 208/120V, 2250A, that has 3 main breakers and one of them is 1000A main breaker whose load side feeds underground direct buried feeder FDR #1. The FDR #1 is Aluminum 2 sets of 4#500kcmil + 1/0G underground direct buried to Panel P. I understand cable size is off based on 1000A breaker and so is equipment grounding conductor size but telling you whats shown on plans.

Panel P is mounted on outside wall of the cluster as shown in sketch.

Since their is outside feeder into Panel P, Panel P is grounded has grounding electrode system ground rods and water pipe no building steel per NEC 2014 section 225.30. So Panel P has two grounding electrode conductors bare going to water pipe and another to rods.

Panel P then feeds meter stacks in Electrical room #1 inside Bldg 2 and Electrical Room #2 inside Bldg 4 as shown on attached sketch Top view.

I have the following questions:

1. Are the underground cables FDR #1 allowed to be direct buried or not? Is their a section that says they must be in conduit underground

2. This is residential apartments. Since their would be bare GEC to water pipe and another to rod and also direct buried cable would come up underground into Panel P per NEC 2014 section 110.27 would fence be required where Panel P is?

3. What are the maximum height requirements from above floor in NEC 2014 for Panel P?

4. I have one outside feeder going to feed the cluster divided by firewall. Would this be in compliance with NEC 2014 section 225.30 or not?



 

augie47

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Not going to do your plans review job for you but, from an inspectors point of view, 2-500 AL on a 1000 amp breaker won't cut it.
 
I know I had some variation of below question prior but design has change a little and I am not sure about few items NEC 2014 code wise.

Please see attached sketches which show cluster of apartment residential one is Top view and second is Elevation view. The cluster has individual buildings 1 to 6 separated by firewall. Their is outside utility transformer which feed outside service entrance rated switchboard.

The service entrance rated switchboard is three phase, 208/120V, 2250A, that has 3 main breakers and one of them is 1000A main breaker whose load side feeds underground direct buried feeder FDR #1. The FDR #1 is Aluminum 2 sets of 4#500kcmil + 1/0G underground direct buried to Panel P. I understand cable size is off based on 1000A breaker and so is equipment grounding conductor size but telling you whats shown on plans.

Panel P is mounted on outside wall of the cluster as shown in sketch.

Since their is outside feeder into Panel P, Panel P is grounded has grounding electrode system ground rods and water pipe no building steel per NEC 2014 section 225.30. So Panel P has two grounding electrode conductors bare going to water pipe and another to rods.

Panel P then feeds meter stacks in Electrical room #1 inside Bldg 2 and Electrical Room #2 inside Bldg 4 as shown on attached sketch Top view.

I have the following questions:

1. Are the underground cables FDR #1 allowed to be direct buried or not? Is their a section that says they must be in conduit underground

2. This is residential apartments. Since their would be bare GEC to water pipe and another to rod and also direct buried cable would come up underground into Panel P per NEC 2014 section 110.27 would fence be required where Panel P is?

3. What are the maximum height requirements from above floor in NEC 2014 for Panel P?

4. I have one outside feeder going to feed the cluster divided by firewall. Would this be in compliance with NEC 2014 section 225.30 or not?
1. No offense, but why would you think direct burial rated cables couldnt be direct buried? Whether it is a good idea, particularly for AL conductors in rocky soil conditions, is another matter but not a code issue.

2. two thing here. First, just from the thinking through this logically standpoint, how many times have you seen electrical equipment on the side of buildings that has no fence around it? (Hint: The answer is everywhere you look). Second, note 110.27 says "live parts" Practically all of the equipment we deal with is in an enclosure and does not have exposed live parts.

3. see 240.24

4. Seems like you have one feeder to a building a structure, what do you think the problem is?
 

hhsting

Senior Member
Not going to do your plans review job for you but, from an inspectors point of view, 2-500 AL on a 1000 amp breaker won't cut it.
Yes cable size not proper is noted third paragraph last sentence post #1. Appreciate it if you answer person who did lookNEC 2014 but confused. Your choice
 
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hhsting

Senior Member
1. No offense, but why would you think direct burial rated cables couldnt be direct buried? Whether it is a good idea, particularly for AL conductors in rocky soil conditions, is another matter but not a code issue.

2. two thing here. First, just from the thinking through this logically standpoint, how many times have you seen electrical equipment on the side of buildings that has no fence around it? (Hint: The answer is everywhere you look). Second, note 110.27 says "live parts" Practically all of the equipment we deal with is in an enclosure and does not have exposed live parts.

3. see 240.24

4. Seems like you have one feeder to a building a structure, what do you think the problem is?
Thanks electrofelon:

#1. Where is it says has to be listed for direct buried in NEC 2014 aside from 110.3(b)?

#2. I havent seen one in residential areas. I have direct buried cables come up underground into Panel P no conduit above ground. Also bare GEC go from Panel P to grounding electrodes. Both of those are they not live energized parts and require fence?
 
Thanks electrofelon:

#1. Where is it says has to be listed for direct buried in NEC 2014 aside from 110.3(b)?

#2. I havent seen one in residential areas. I have direct buried cables come up underground into Panel P no conduit above ground. Also bare GEC go from Panel P to grounding electrodes. Both of those are they not live energized parts and require fence?
#1 I dont think there is anything in the NEC that specifically gives you permission to use direct bury conductors. Generally the NEC tells you NOT to do something rather than gives you permission to do something. Look at 300.5 both wording and table. Direct bury is all over. Note you need conduit above ground and down to the burial depth, 300.5(D)(1)

#2 no GEC and insulated direct bury conductors are not live energized parts for fencing purposes. You need conduit though as mentioned above, 300.5(D).
 

hhsting

Senior Member
#1 I dont think there is anything in the NEC that specifically gives you permission to use direct bury conductors. Generally the NEC tells you NOT to do something rather than gives you permission to do something. Look at 300.5 both wording and table. Direct bury is all over. Note you need conduit above ground and down to the burial depth, 300.5(D)(1)

#2 no GEC and insulated direct bury conductors are not live energized parts for fencing purposes. You need conduit though as mentioned above, 300.5(D).
I looked but didn’t find much 300.5 in terms of listed direct buried cable wording. Also depend on cable type some cables are allowed to be direct buried under ground and some are not.

I have note that says install comply with 300.5 for direct buried but certain cable types are not allowed to be direct buried.

No cable types are mentioned. I will ask the designer for cable type and see if its allowed to be underground direct buried or not depending on that cable type section uses permitted or uses not permitted. Will get back to you cable type
 

roger

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Out of curiosity, do you tell those whose plans you are reviewing that you approve or reject said plans based on input from an internet forum?

Roger
 
I looked but didn’t find much 300.5 in terms of listed direct buried cable wording. Also depend on cable type some cables are allowed to be direct buried under ground and some are not.

I have note that says install comply with 300.5 for direct buried but certain cable types are not allowed to be direct buried.

No cable types are mentioned. I will ask the designer for cable type and see if its allowed to be underground direct buried or not depending on that cable type section uses permitted or uses not permitted. Will get back to you cable type
The direct burial thing is a little odd. The NEC doesn't really say much as far as specifically stating that a certain conductor is suitable for direct burial. The only specific instance I can find is for UF, 340.2. Often they will just say "for direct bury if identified for such use" i.e. for tray cable 336.12(4). Strangely, there is no mention of direct burial in the article for SE/USE. I guess it is typically in the product standards and has to be marked on the cable or conductor.
 

hhsting

Senior Member
Out of curiosity, do you tell those whose plans you are reviewing that you approve or reject said plans based on input from an internet forum?

Roger
Depends. If their is concrete proof written in NEC from section quoted on forum then I might otherwise no.

Previously I read opinions given on people about items I didn’t consider to implement at plan review time later turns out to be true during field inspection time or someone else caught. I was like oh that guy was right on Mike holts forum. Their are times that didnt happened. However regardless this forum helps most of time
 
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hhsting

Senior Member
The direct burial thing is a little odd. The NEC doesn't really say much as far as specifically stating that a certain conductor is suitable for direct burial. The only specific instance I can find is for UF, 340.2. Often they will just say "for direct bury if identified for such use" i.e. for tray cable 336.12(4). Strangely, there is no mention of direct burial in the article for SE/USE. I guess it is typically in the product standards and has to be marked on the cable or conductor.
What about this for USE cable NEC 2014 section 338.10(B)(4)(b): Type USE cable installed as underground feeder or branch circuit cable shall comply with part II of Article 340.

Part II of Article 340.10(1) uses permitted: For use underground, including direct burial in earth.... ?
 
What about this for USE cable NEC 2014 section 338.10(B)(4)(b): Type USE cable installed as underground feeder or branch circuit cable shall comply with part II of Article 340.

Part II of Article 340.10(1) uses permitted: For use underground, including direct burial in earth.... ?
Not sure if it said on the plans you are reviewing what the conductor type is. If its USE-2 its always fine for direct bury per the product standard. IF it doesnt say, just make a note on the plans, "conductors to be of type suitable for direct bury" DONE, MOVE ON.
 

roger

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Electrician
Not sure if it said on the plans you are reviewing what the conductor type is. If its USE-2 its always fine for direct bury per the product standard. IF it doesnt say, just make a note on the plans, "conductors to be of type suitable for direct bury" DONE, MOVE ON.
And that covers it.

Roger
 
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