No ground to detached structure ok?

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ritelec

ritelec

Senior Member
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Jersey
It was presented to me that prior to 2008 a ground was not required to be brought to a detached structure when bringing out a feeder
Only two hots and the neutral

Is this true. I don't remember that.

Thank you
 
Thinking here. Where does that leave a person if this three wire panel is installed and you wanted gas or water or fios or cable or any other metal grounded object out there.

Wonder if I would have known this if I would not have brought out the ground when I did my garage in 89'

I wonder also now how also it was written that grounding and bonding of the neutral was not only at the first over current protection.


This is blowing me away. I feel faint.
 
Since you have only the neutral, you would need to install a GES for the building and also bond the neutral to the ground/ EGC to provide a fault clearing path.
 
ritelec said:
It was presented to me that prior to 2008 a ground was not required to be brought to a detached structure when bringing out a feeder
Only two hots and the neutral

Is this true. I don't remember that.

Thank you
Click to expand...

Equipment grounding conductor.

I used that exception all the time to save those installing a manufactured home from having to use a 4-wire system when the disconnect was on a pole or if they built a barn first and feed the home from the meter on the barn.
 
jxofaltrds said:
Equipment grounding conductor.

I used that exception all the time to save those installing a manufactured home from having to use a 4-wire system when the disconnect was on a pole or if they built a barn first and feed the home from the meter on the barn.
Click to expand...

Thank you for the responses.

Would that exception not have worked because part of that exemption mentioned no grounded metal ?
And I would think prefabed homes have grounded metal ( or well at that time before all these plastic systems )
 
ritelec said:
Thank you for the responses.

Would that exception not have worked because part of that exemption mentioned no grounded metal ?
And I would think prefabed homes have grounded metal ( or well at that time before all these plastic systems )
Click to expand...

Think parallel 'paths'. Phone, cable, metal water lines.

Draw two boxes on a piece of paper. Draw the 3-wire between them.

If no other lines (paths) can be drawn (4th line) then the exception was allowed. Make sense?
 
jxofaltrds said:
Equipment grounding conductor.

I used that exception all the time to save those installing a manufactured home from having to use a 4-wire system when the disconnect was on a pole or if they built a barn first and feed the home from the meter on the barn.
Click to expand...
:?

Manufactured homes are (and have been for a long time) permitted to have service equipment installed in/on the home. They never absolutely required a 4 wire supply until 2008 when all separate structures required a separate EGC.

Mobile homes have always required a 4 wire feeder from the service disconnect or when not supplied by a service a service rated disconnect. Even before 2008 this service rated disconnect could have been supplied with only a three wire feeder, but the individual feeder to the home itself had to be 4 wire.
 
kwired said:
:?

Manufactured homes are (and have been for a long time) permitted to have service equipment installed in/on the home. They never absolutely required a 4 wire supply until 2008 when all separate structures required a separate EGC.

Mobile homes have always required a 4 wire feeder from the service disconnect or when not supplied by a service a service rated disconnect. Even before 2008 this service rated disconnect could have been supplied with only a three wire feeder, but the individual feeder to the home itself had to be 4 wire.
Click to expand...

You are partially correct.

Here is why the 4-wire would have been required:

550.32 Service Equipment.
(A) Mobile Home Service Equipment. The mobile home
service equipment shall be located adjacent to the mobile
home and not mounted in or on the mobile home. The
service equipment shall be located in sight from and not
more than 9.0 m (30 ft) from the exterior wall of the mobile
home it serves. The service equipment shall be permitted to
be located elsewhere on the premises, provided that a disconnecting
means suitable for use as service equipment islocated within sight from and not more than 9.0 m (30 ft)
from the exterior wall of the mobile home it serves and is
rated not less than that required for service equipment in
accordance with 550.32(C). Grounding at the disconnecting
means shall be in accordance with 250.32.

This is what most installers did because they did not go to the next:
(B) Manufactured Home Service Equipment. The manufactured
home service equipment shall be permitted to be
installed in or on a manufactured home, provided that all of
the following conditions are met:

You can STILL use a 3-wire to the manufactured home.

Example:

Meter on the home or a pole or wherever.
Run the 3-wire underground (outside the structure) concrete slab or not, up out of the 'ground' and straight up into the factory installed panel.
Now you will have to 'bond' inside the panel.

Now it gets better. This is a permanent install.
http://www.tiedown.com/pdf/d552.pdf
 
In electrical terms, how is a second building different from the service? Why do the electrons behave differently on the load side of the service? Either both the service and the second building feeder are safe using the grounded conductor as both the grounded and grounding conductor or neither one is safe unless you install an EGC. There is no way that one requires an EGC for safety and the other doesn't, other than the code rule.
 
jxofaltrds said:
You are partially correct.

Here is why the 4-wire would have been required:

550.32 Service Equipment.
(A) Mobile Home Service Equipment. The mobile home
service equipment shall be located adjacent to the mobile
home and not mounted in or on the mobile home. The
service equipment shall be located in sight from and not
more than 9.0 m (30 ft) from the exterior wall of the mobile
home it serves. The service equipment shall be permitted to
be located elsewhere on the premises, provided that a disconnecting
means suitable for use as service equipment islocated within sight from and not more than 9.0 m (30 ft)
from the exterior wall of the mobile home it serves and is
rated not less than that required for service equipment in
accordance with 550.32(C). Grounding at the disconnecting
means shall be in accordance with 250.32.

This is what most installers did because they did not go to the next:
(B) Manufactured Home Service Equipment. The manufactured
home service equipment shall be permitted to be
installed in or on a manufactured home, provided that all of
the following conditions are met:

You can STILL use a 3-wire to the manufactured home.

Example:

Meter on the home or a pole or wherever.
Run the 3-wire underground (outside the structure) concrete slab or not, up out of the 'ground' and straight up into the factory installed panel.
Now you will have to 'bond' inside the panel.

Now it gets better. This is a permanent install.
http://www.tiedown.com/pdf/d552.pdf
Click to expand...
Ok an anchoring system like you provided a link to is the main difference here. I never see manufactured homes that are not on a permanent foundation, then again maybe I just assumed some manufactured homes were mobile homes.

Other situation that usually comes up is if the panel is not at an exterior wall you will be running a feeder with separate EGC to it anyway because of 230.70(A)(1), unless you have an AHJ that is pretty relaxed on how far service conductors can enter a building.

Many homes will not have a panel in an exterior wall because of thermal insulation issues created if it is in an external wall.
 
don_resqcapt19 said:
In electrical terms, how is a second building different from the service? Why do the electrons behave differently on the load side of the service? Either both the service and the second building feeder are safe using the grounded conductor as both the grounded and grounding conductor or neither one is safe unless you install an EGC. There is no way that one requires an EGC for safety and the other doesn't, other than the code rule.
Click to expand...
I have been asking the same question since the 90's. I can only figure that it has to do with the way our power grid is set up. Somebody or some group set out to change the entire US but only managed to get as far as the rules for inside wire men.
 
kwired said:
Ok an anchoring system like you provided a link to is the main difference here. I never see manufactured homes that are not on a permanent foundation, then again maybe I just assumed some manufactured homes were mobile homes.

Other situation that usually comes up is if the panel is not at an exterior wall you will be running a feeder with separate EGC to it anyway because of 230.70(A)(1), unless you have an AHJ that is pretty relaxed on how far service conductors can enter a building.

Many homes will not have a panel in an exterior wall because of thermal insulation issues created if it is in an external wall.
Click to expand...

ActionDave said:
I have been asking the same question since the 90's. I can only figure that it has to do with the way our power grid is set up. Somebody or some group set out to change the entire US but only managed to get as far as the rules for inside wire men.
Click to expand...

My example meet your reference:
(1) Readily Accessible Location. The service disconnecting
means shall be installed at a readily accessible location
either outside of a building or structure or inside nearest the
point of entrance of the service conductors.
 
don_resqcapt19 said:
In electrical terms, how is a second building different from the service? Why do the electrons behave differently on the load side of the service? Either both the service and the second building feeder are safe using the grounded conductor as both the grounded and grounding conductor or neither one is safe unless you install an EGC. There is no way that one requires an EGC for safety and the other doesn't, other than the code rule.
Click to expand...

In the 2008 ROPs there are many proposals on this including 5-119 Log 2395 submitted by Mike Holt.
In substantiating the change requiring the EGC between buildings the prime reason, if I read correctly, is the dangers, both fire and shock, that occur when you end up with an alternate path (communication cables, piping, etc). Although the Code panels normally don't address "what ifs", the high probability of a system being installed after the electrical that would allow such a path was found to warrant the requirement.
The CMP followed the thinking that accompanied the earlier requirement for ranges and clothes dryers.
 
augie47 said:
In the 2008 ROPs there are many proposals on this including 5-119 Log 2395 submitted by Mike Holt.
In substantiating the change requiring the EGC between buildings the prime reason, if I read correctly, is the dangers, both fire and shock, that occur when you end up with an alternate path (communication cables, piping, etc). Although the Code panels normally don't address "what ifs", the high probability of a system being installed after the electrical that would allow such a path was found to warrant the requirement.
The CMP followed the thinking that accompanied the earlier requirement for ranges and clothes dryers.
Click to expand...
Augie,
My problem is that the second building is electrically no different from a service and not only are parallel paths not prohibited at services, they are actually required by the code rules.

Some of those parallel paths could be a metal underground water piping system, the shield of the TV cable coax, or the shield of a underground phone line. If these items are at the building the code requires the creation of the parallel path. A parallel path is also created when metallic raceways are used between the meter and the service equipment. (the use of rigid metal conduit is required in my area, but is permitted almost everywhere)

If parallel paths are a hazard, they are a hazard at both services and second buildings.

This is just one of a number of NEC rules where the CMPs are trying to get us to believe that the electrons change their behavior based on who owns them. That is they behave one way when the utility owns them and then a different way when the customer owns them.:)
 
To some degree you are "preaching to the choir" as I agree if you fed that same building by a POCO service we would not have the EGC. Apparently the CMP saw wisdom in Mike proposal.
I don't have the talent to copy their comments and the substantiation is lengthy.
 
don_resqcapt19 said:
Augie,
My problem is that the second building is electrically no different from a service and not only are parallel paths not prohibited at services, they are actually required by the code rules.
Click to expand...

I totally agree. I also believe requiring separate EGC between buildings is a start in the direction we should try to go. You have to start somewhere. Making us run separate EGC to ranges and dryers back in 1996 is also a similar step in that direction.

It will be much harder to take the next step of getting everyone on board with a separate EGC from the transformer to service equipment. For one thing it gets more into NESC, utilities, etc. and not so much NEC. But there would be advantages to not utilizing multiple point grounded systems. It is a little hard to prove the risks are high enough to justify the expense of changing so much existing infrastructure though. It is also not going to be very effective to have spot locations one way and the rest the other way, you about have to change it all or leave it as is.
 
I don't see that having a EGC going to an out building makes all that much difference one way or the other.

The real answer might well be requiring an SDS at such structures, if the problem is enough of an issue to actually worry all that much about. But I am not sure that gains you all that much either as underground piping systems could well be connected to both the service and the SDS on the neutral and you could still have current on the metal pipe.

So you get rid of underground metal pipe.

How far are you going to go to deal with a problem that is not all that much of a problem in the first place.
 
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