4 wire to sub-panel

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JDB3

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San Antonio, Texas
Some one else is wiring the small residential cottage. I was asked to wire & connect the ac & furnace. The 200 amp service is on the pole feed underground to the cottage. Upon opening the panel inside the cottage, I discovered that the "electrician" just ran 3 conductors to this panel. He did run & connect 2 ground rods to this panel. Just one circuit connected at this time, but both neutral & ground on same bar (GE panel with bar across to each side bar0>

What code article would best describe to the owner the code violation?

Sorry for the way this is stated, been going since 4:30 this morning. :sleep::sleep:
 
This was done in the county where no inspection is made (only if the owner has some problem & requests that the state comes out). The power company builds & sets on their pole the riser, meter & and service panel (Square D QO816M200FTRB [200 amp main 8 full spaces]). No screws or nails supporting the panel in most cases. Then the rest is up to the owner, no inspections normally.

Thanks one & all.:D
 
Now the owner wants to know why this is code, said that for 80 (?) years it had been fine with a 3-wire system. I was told years ago, that having a 4-wire system was safer "because" if something went to ground, the extra distance it traveled = more resistance and would react faster {or something like that}.

What do you'll think would be a good answer for a homeowner? The "electrician" had him buy 4 conductor for the range ! I did not see any 10/3 w/g there for the dryer though ( unless he planed to use the #6/3 w/g for the dryer) ? And then, good luck on getting it on a 30 amp breaker.
 
The cynic in me says that the code change came around just because of more dumbing down of the code and the general tone a busy-bodyness that has worked its way into the last three or four cycles.

I imagine the reason given is that it is too hard to make sure there is not a metallic path between structures.

As far as I am concerned the install is fine and the HO is right to question why he has to change it.

Wherever the neutral is bonded is the length of the fault clearing path so if you ran an EGC to the house and bonded at the meter you would have a longer fault clearing path.
 
}}Could be but most of Texas is on the 2014 {{

In Texas, we have state master electrician license (required) & state electrical contractor license, as well as state journeyman & state apprentice licensing. These are a requirement to do electrical work in the state. Outside of an area, where no inspection is required, the state requirements are in effect (meaning that the 2014 NEC is in effect). Where there is a local jurisdiction involved, they may or may not have adopted the latest code.

The state informs us when they have adopted the latest code & when it is to go into effect. This gives us time to (in most cases), know what code changes may affect our bids.

My feeling on this is, if something did happen, the state may get involved, and if in local AHJ, then they would be liable for not enforcing the latest NEC. Some local AHJ, state in their code, which ever code is more stringent (stricter). This is the reason that I try to follow the intent of the latest code.
 
First one needs to determine if the disconnect on the pole is considered the service disconnect. Strictly from NEC perspective it likely is, but it also depends on where the "service point" is located as well.

Some AHJ's do determine that equipment provided by the POCO like the OP suggests is the case here - that they want to still consider that to be service conductors leaving that equipment because there is a possibility that if the POCO has control over it- they could one day replace it with something that no longer provides proper service disconnecting means.

But even outside of that - still is possible to run 4 conductors to the house - but if the two "grounded conductors" are connected to one another on both ends of the run, you now have a parallel conductor and they both need to be 1/0 AWG minimum, same size, type, length, and have other same electrical characteristics.

So as far as violations go - depends on some determinations for the 3 vs 4 wire feeder, but in either case you likely have a parallel conductor rules violation.



Why did they change this feeders to separate buildings rule (I believe in 2008)?

Though we did do it the other way for like 100 years with pretty much little troubles, it makes sense.

When we have current on a conductor resistance in that conductor causes voltage drop. Now if this is a grounded conductor and you are connecting equipment The past practices generally had limited problems, but there were still cases where there are problems, some minor, some quite serious. I still think it was overall a good idea to make the change, even though it does add some cost at times compared to past similar installs.
 
Why did they change this feeders to separate buildings rule (I believe in 2008)?

Though we did do it the other way for like 100 years with pretty much little troubles, it makes sense.

When we have current on a conductor resistance in that conductor causes voltage drop. Now if this is a grounded conductor and you are connecting equipment The past practices generally had limited problems, but there were still cases where there are problems, some minor, some quite serious. I still think it was overall a good idea to make the change, even though it does add some cost at times compared to past similar installs.
Why did they change this feeders to separate buildings rule (I believe in 2008)?

Thanks Kwired

Could you give me some examples on this (some minor some quite serious problems). It would help me to explain to the owner. Thanks again...
 
JDB3 said:
Why did they change this feeders to separate buildings rule (I believe in 2008)?

Though we did do it the other way for like 100 years with pretty much little troubles, it makes sense.

When we have current on a conductor resistance in that conductor causes voltage drop. Now if this is a grounded conductor and you are connecting equipment The past practices generally had limited problems, but there were still cases where there are problems, some minor, some quite serious. I still think it was overall a good idea to make the change, even though it does add some cost at times compared to past similar installs.
Why did they change this feeders to separate buildings rule (I believe in 2008)?

Thanks Kwired

Could you give me some examples on this (some minor some quite serious problems). It would help me to explain to the owner. Thanks again...
Click to expand...
Some of the worst case real examples go further back then just service equipment and get into the fact that POCO distribution does use the grounded conductor to carry "normal" operating current quite often, both at medium and low voltages.

Most electrocution stories you hear of at marinas, docks, around boat hoists are a good example of what happens when you have equipment grounding voltage over "true earth" voltage conditions. Swimming pools we have additional protection because of equipotential bonding that is done at these locations, but that is not so easy to achieve at a larger body of water.

What seems to often happen in cases where people are puzzled why the electrocution happened when equipment grounding seemed to be in good condition and even GFCI protection was utilized is simple to explain - not so easy for all to comprehend though. Same electrocution event possibly happens even if the service disconnect is opened at the location of the accident. Why? The equipment grounding conductor is bonded to the grounded service conductor back at the service - or in some older installations at least at the disconnecting means of the last building or structure supplied. What ever voltage drop may be across the grounded supply conductor exists at the EGC in relation to other "earth potential" items. You can read this easily with a meter and see it change as the load changes on the grounded conductor. You can drive a ground rod and lower that potential - but it is only effective a short distance from the rod, same with other electrodes. This isn't the primary intent of grounding elecrodes.

Now go further upstream into the POCO supply, they do not use separate EGC's and bond and earth many times to the grounded conductor, and of course their primary grounded conductor is bonded to secondary grounded conductors so it is nothing more then an extension of that conductor. Any voltage drop imposed on that extended conductor is also extended to your service ground, equipment grounding conductors, and anything else you bond to it. So a voltage drop of only three to five volts seems like nothing on a 7200 volts to ground system, tell the guy in the water that is near the boat hoist that is at 3 to 5 volts to ground that it is nothing - and he may get elecrocuted anyway.

I kind of rambled on a little plus gave one of the most extreme cases - but hopefully it has some meaning to you. Keeping "stray voltages" off the EGC and all other bonded objects is the main goal.

People get into similar troubles with corner grounded systems when they don't fully understand that grounded conductor is carrying current- it is when we isolate that current carrying portion from non current carrying portions (the EGC) that we create an additional safety layer - and it doesn't matter if dealing with a 120 volt circuit or one operating at thousands of volts.
 
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