Separate Structures
- Thread starter iwire
- Start date
- Status
- Location
- Massachusetts
Re: Separate Structures
Looks like I will have to put in 4 separate posts so I will only have one circuit per structure.
Bob
I did not do anything yet, I took a few days off instead.
Looks like I will have to put in 4 separate posts so I will only have one circuit per structure.
Bob
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Re: Separate Structures
It seems that by adding the definition for a 'Structure' in the 2005 NEC has created more problems than it has solved since every section using the word 'Structure' has not been re-written.
Is it me or does this seem ridiculous? How would four posts next to each other be really any different electrically than one post with 4 circuits?
It seems that by adding the definition for a 'Structure' in the 2005 NEC has created more problems than it has solved since every section using the word 'Structure' has not been re-written.
pierre
Senior Member
- Location
- Westchester County, New York
Re: Separate Structures
I admit that this definition has created some issues. With the NEC trying to be more global and consistant with the building code, I see the need for common definitions - it is just sometimes we get unexpected results. The good part of this is a new proposal(s).
Bob's example is one that does not make a lot of sense.
In a separate structure, the GE System is mostly for lightning protection. I can see the need for lightning protection for this in some areas of the country, but not all.
This is where some creative ideas are needed.
Bob
You need another week off while we come up with a solution
I admit that this definition has created some issues. With the NEC trying to be more global and consistant with the building code, I see the need for common definitions - it is just sometimes we get unexpected results. The good part of this is a new proposal(s).
Bob's example is one that does not make a lot of sense.
In a separate structure, the GE System is mostly for lightning protection. I can see the need for lightning protection for this in some areas of the country, but not all.
This is where some creative ideas are needed.
Bob
You need another week off while we come up with a solution
Re: Separate Structures
Actually, a subpanel at a separate building does need a ground rod that is connected to the equipment grounding conductor. See NEC 250.32 There are several reasons for this:
1. If a place is dependent on ground rods for grounding then putting more rods here and there helps lower ground resistance.
2. A little bit of lightning can do a lot of damage. If silent or invisible lightning hits the outbuilding it has a local place to go. Otherwise, it could toast the underground feeder. Same thing can be said about grounding aluminum siding.
3. A local ground rod acts as a drain for static electricity other than lightning.
4. A local ground rod acts as a backup for the equipment grounding conductor.
If you are putting 2 ore more branch circuits on the same post then a local ground rod is not a bad idea. If all 4 circuit pass thourgh a pull box you could stick a grounding bar in the pull box.
Actually, a subpanel at a separate building does need a ground rod that is connected to the equipment grounding conductor. See NEC 250.32 There are several reasons for this:
1. If a place is dependent on ground rods for grounding then putting more rods here and there helps lower ground resistance.
2. A little bit of lightning can do a lot of damage. If silent or invisible lightning hits the outbuilding it has a local place to go. Otherwise, it could toast the underground feeder. Same thing can be said about grounding aluminum siding.
3. A local ground rod acts as a drain for static electricity other than lightning.
4. A local ground rod acts as a backup for the equipment grounding conductor.
If you are putting 2 ore more branch circuits on the same post then a local ground rod is not a bad idea. If all 4 circuit pass thourgh a pull box you could stick a grounding bar in the pull box.
- Location
- Massachusetts
Re: Separate Structures
The total resistance of the fault path would be to high to be effective.
A local ground rod is worthless as a back up to the EGC on a 208 volt circuit.
The total resistance of the fault path would be to high to be effective.
- Location
- Massachusetts
Re: Separate Structures
Originally posted by pierre:
Bob
You need another week off while we come up with a solution
This work is being done at what I will call a popular fairground. These circuits feed food service equipment in tents. It is very likely over the next few months 600,000+ people will pass by this work.
Many of these people will be in various states of inebriation.
I am quite concerned about the safety, code compliance and quality of the installation.
- Location
- Massachusetts
Re: Separate Structures
Plugs are disconnecting means.
The wood posts the outlets are mounted on are permanent.
The tent structures are temporary and are simply roofs with open sides. In these temporary structures are located tables with the food service equipment.
What we have done is put a short cord on the machines to provide a disconnecting means right at the machine. From there a flexible cord runs 15' at most to the outlets on the post.
The posts with the plugs are directly outside the tent structure providing the disconnecting means required for a separate structure.
The plugs at the units provide the disconnecting means for servicing the unit.
The outlets on the post are getting high quality metal in-use covers deep enough to work with the 10/3 cord and twist lock plug.
I am trying to provide the safest installation I can given the circumstances.
Plugs are disconnecting means.
The wood posts the outlets are mounted on are permanent.
The tent structures are temporary and are simply roofs with open sides. In these temporary structures are located tables with the food service equipment.
What we have done is put a short cord on the machines to provide a disconnecting means right at the machine. From there a flexible cord runs 15' at most to the outlets on the post.
The posts with the plugs are directly outside the tent structure providing the disconnecting means required for a separate structure.
The plugs at the units provide the disconnecting means for servicing the unit.
The outlets on the post are getting high quality metal in-use covers deep enough to work with the 10/3 cord and twist lock plug.
I am trying to provide the safest installation I can given the circumstances.
- Location
- Massachusetts
Re: Separate Structures
Gotta look at the reference before commenting on it.
525.21(A) may well be an issue I will be doing some reading.
This is going a major problem at this point.
[ May 01, 2005, 10:21 AM: Message edited by: iwire ]
Gotta look at the reference before commenting on it.
525.21(A) may well be an issue I will be doing some reading.
This is going a major problem at this point.
[ May 01, 2005, 10:21 AM: Message edited by: iwire ]
pierre
Senior Member
- Location
- Westchester County, New York
Re: Separate Structures
Bob
"This work is being done at what I will call a popular fairground. These circuits feed food service equipment in tents. It is very likely over the next few months 600,000+ people will pass by this work.
I am quite concerned about the safety, code compliance and quality of the installation."
Of the 600,000 or so, I bet there will be quite a few electricians
Your concern for safety, IN MY OPINION, will be in the form of a good Equipment Ground Conductor creating an Effective Ground Fault Current Path back to the source - as you mentioned certainly not part of the Grounding Electrode System we are discussing.
To me it is still hard to see what the ground rod(s) are going to perform for this type of installation.
I know the lightning thing I see a post with receptacles as maybe... well... I don't know.
Bob
"This work is being done at what I will call a popular fairground. These circuits feed food service equipment in tents. It is very likely over the next few months 600,000+ people will pass by this work.
I am quite concerned about the safety, code compliance and quality of the installation."
Of the 600,000 or so, I bet there will be quite a few electricians
Your concern for safety, IN MY OPINION, will be in the form of a good Equipment Ground Conductor creating an Effective Ground Fault Current Path back to the source - as you mentioned certainly not part of the Grounding Electrode System we are discussing.
To me it is still hard to see what the ground rod(s) are going to perform for this type of installation.
I know the lightning thing
I see a post with receptacles as maybe... well... I don't know.
- Location
- Massachusetts
Re: Separate Structures
And while it is not good news I still want / need to know about it.
I may have to go with a some shunt trip type control.
While I had remembered to look at Article 520 for some other work on these fair grounds I had not thought of reading 525.
Thanks for pointing it out I had totally overlooked that Article.
And while it is not good news I still want / need to know about it.
I may have to go with a some shunt trip type control.
While I had remembered to look at Article 520 for some other work on these fair grounds I had not thought of reading 525.
Re: Separate Structures
Bob,
To be pefectly honest with you,525.21(a) is the only thing I've got high-lighted in that Article.
Just now reading your post,it came to mind.
I've never reseached the whole article word-for- word either Bob. Not the -every day- installation.
[ May 01, 2005, 11:13 AM: Message edited by: dillon3c ]
Bob,
To be pefectly honest with you,525.21(a) is the only thing I've got high-lighted in that Article.
Just now reading your post,it came to mind.
I've never reseached the whole article word-for- word either Bob. Not the -every day- installation.
[ May 01, 2005, 11:13 AM: Message edited by: dillon3c ]
- Location
- Massachusetts
Re: Separate Structures
No it's not for me either, I spend most of my time in schools, offices, retail, manufacturing type buildings.
milwaukeesteve
Senior Member
- Location
- Milwaukee, WI
Re: Separate Structures
If we were to put receptacles in a campground for RV's and for tent sites, we would not have to install disconnecting means for most of the outlets (only certain sites need it).
Typically we would install these 15A 20A and 30A recepts by mounting them to a 4x4 post. We don't drive ground rods at these outlet posts.
I don't see any thing different here with Bob's example. If Bob had installed a galvanized unistrut instead of a post would this be any different? What about a Fence post? Is that a 'structure' or is that just a fence?
If we were to put receptacles in a campground for RV's and for tent sites, we would not have to install disconnecting means for most of the outlets (only certain sites need it).
Typically we would install these 15A 20A and 30A recepts by mounting them to a 4x4 post. We don't drive ground rods at these outlet posts.
I don't see any thing different here with Bob's example. If Bob had installed a galvanized unistrut instead of a post would this be any different? What about a Fence post? Is that a 'structure' or is that just a fence?
Re: Separate Structures
525.21(a) seems to be for "rides" ,even though concession is mentioned once at the begining of 525.21(a) the rest of it focuses on rides.
Is there any place to mount a disc.? would it be resonable to have two matching cord caps on strain relief connectors wired to this fusable disc.
two cents don't go to far these days!
frank
525.21(a) seems to be for "rides" ,even though concession is mentioned once at the begining of 525.21(a) the rest of it focuses on rides.
Is there any place to mount a disc.? would it be resonable to have two matching cord caps on strain relief connectors wired to this fusable disc.
two cents don't go to far these days!
frank
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