Grounding and Grounded as ONE, "WHEN"

[jamesoftn]

When did the requirement or was it always a requirement to install a equipment grounding conductor and a grounded conductor to a sub panel. There are a lot of older installations that have only one of these installed, normally a white wire with metallic conduit but the terminal buss is bonded. Around what time frame was this changed.

 

[augie47]

So far I can not confirm when it was allowed, but the oldest NEC reference I have here is 1990, and it was not allowd then.

 

[steve66]

Is a ground wire ever required if you run metallic conduit?? Or is that not permitted for subpanel feeders?

Steve

 

[jxofaltrds]

When did the requirement or was it always a requirement to install a equipment grounding conductor and a grounded conductor to a sub panel. There are a lot of older installations that have only one of these installed, normally a white wire with metallic conduit but the terminal buss is bonded. Around what time frame was this changed.

If the 1962 NEC was the first year for EGC's wouldn't it be then?

 

[tom baker]

Is a ground wire ever required if you run metallic conduit?? Or is that not permitted for subpanel feeders?

Steve

The EGC is defined as the conductive path (not ground wire-see the 2008 NEC defintion of ground-and use that defintion in your sentance)
250.118 gives us the list of what the conductive path is allowed to be.
A neutral (grounded conductor)is not required to be installed if there are no line to neutral loads.
Many electricians will install a wire type EGC when not required by the NEC.
A feeder panel in a building cannot have a neutral to ground connection in the panel. In a separate building yes and no, depending on when it was installed. Under the 08 NEC, the neutral is floated, in electrician lingo at separate buildings.

 

[al hildenbrand]

If the 1962 NEC was the first year for EGC's wouldn't it be then?

The 1962 NEC gave us the first general requirement for the installation of grounding type receptacles throughout the premises wiring (system).

That's different than the EGC. Prior to 1962, grounding type receptacles were only required in specific locations.

I apprenticed in the late Sixties and was taught to not install the main bonding jumper, supplied with a panel, when the panel was used as a subpanel. So, the requirement predates then. (As Tom points out, there are some exceptions to this.)

 

[jxofaltrds]

The 1962 NEC gave us the first general requirement for the installation of grounding type receptacles throughout the premises wiring (system).

That's different than the EGC. Prior to 1962, grounding type receptacles were only required in specific locations.

I apprenticed in the late Sixties and was taught to not install the main bonding jumper, supplied with a panel, when the panel was used as a subpanel. So, the requirement predates then. (As Tom points out, there are some exceptions to this.)

Did a little more research.

In 1947, the NEC first required grounding type (3-prong) receptacles for the laundry.

In 1956, the required use of grounding type receptacles was extended to basements, garages, outdoors and other areas where a person might be standing on ground.

Finally, in 1962 the NEC was revised to require all branch circuits to include a grounding conductor or ground path to which the grounding contacts of the receptacle must be
connected.

 

[al hildenbrand]

When did the requirement or was it always a requirement to install a equipment grounding conductor and a grounded conductor to a sub panel. There are a lot of older installations that have only one of these installed, normally a white wire with metallic conduit but the terminal buss is bonded. Around what time frame was this changed.

I think this is an interesting question.

The question is not about the Outlet or Branch Circuit, but rather, is about a Feeder to a subpanel.

 

[jxofaltrds]

Did a little more research.

In 1947, the NEC first required grounding type (3-prong) receptacles for the laundry.

In 1956, the required use of grounding type receptacles was extended to basements, garages, outdoors and other areas where a person might be standing on ground.

Finally, in 1962 the NEC was revised to require all branch circuits to include a grounding conductor or ground path to which the grounding contacts of the receptacle must be
connected.

The reason for my info is, wouldn't in be in one of the above years that feeders for subs was addressed?

Karl Riley once posted that paralleled conductors goes back to 1934.

 

[al hildenbrand]

The reason for my info is, wouldn't in be in one of the above years that feeders for subs was addressed?

I don't think so.

Consider dwellings wired in the early decades of the 1900s where the primary Chapter 3 method is rigid metal conduit. The importance of electrical continuity in the raceway system, required by the Codes of that time, has nothing to do with the neutral path for outlets, and the outlets were virtually never grounding type. The tight mechanical assembly was required for a ground fault current so it would clear the OCPD.

--But--

As James (of Tennessee) notes in his OP, I, too, recall observing inconsistencies in subpanel neutral terminals, that is, whether they are bonded to the enclosure of the subpanel, or not.

 

[steve66]

The EGC is defined as the conductive path (not ground wire-see the 2008 NEC defintion of ground-and use that defintion in your sentance)
250.118 gives us the list of what the conductive path is allowed to be.

That's basiclly what I was thinking. The metallic conduit is the ECG, so the additional "ground wire" or EGC "conductor" is not needed.

When did the requirement or was it always a requirement to install a equipment grounding conductor and a grounded conductor to a sub panel.

If the metal conduit is serving the as the EGC (or ground), I'm not sure it's ever been required. Or am I misunderstanding the question?

There are a lot of older installations that have only one of these installed, normally a white wire with metallic conduit but the terminal buss is bonded. Around what time frame was this changed.

Again, if the conduits serves as the EGC, and the white wire is the grounded conductor (neutral), the only violation I see is that the bonding jumper should be removed (if that what you mean when you say the "terminal buss is bonded".)

Edit: I'm assuming the panel and subpanel are in the same building, since the OP didn't say separate buildings.

Steve

 

[jxofaltrds]

I don't think so.

Consider dwellings wired in the early decades of the 1900s where the primary Chapter 3 method is rigid metal conduit. The importance of electrical continuity in the raceway system, required by the Codes of that time, has nothing to do with the neutral path for outlets, and the outlets were virtually never grounding type. The tight mechanical assembly was required for a ground fault current so it would clear the OCPD.

--But--

As James (of Tennessee) notes in his OP, I, too, recall observing inconsistencies in subpanel neutral terminals, that is, whether they are bonded to the enclosure of the subpanel, or not.

If they added EGC's wouldn't they tell us how they were to be installed?

I am not talking about the 'outlets'. Just gave the years as a reference thinking that the feeders may have been addressed in one of those years.

I can see the grounded conductor being bonded to the sub prior to the addition of the EGCs. This is where the problem starts. EGCs were added to sub panels that were installed as 3 wire systems. Prior to the EGCs no problem with the bonding.

 

[bphgravity]

Here is a very brief and basic history of grounding and the NEC:

1892 – NYBFU prohibits the grounding of electrical systems and requires existing systems to be removed from service.

1897 – Mandatory grounding of Lightning Arrestors only.

1899 – Grounding becomes permitted but not required.

1901 – NEC Rule 13A contains provisions for grounding.

1903 – “May be grounded” changed to “should preferably be grounded.

1913 – First code edition to mandate the grounding of one circuit conductor of a service.

1918 – First code edition prohibiting the grounded circuit conductor to be bonded to equipment – Rule 15A.

1962 – First code edition requiring equipment grounding for branch circuits.

 

[al hildenbrand]

Again, if the conduits serves as the EGC, and the white wire is the grounded conductor (neutral), the only violation I see is that the bonding jumper should be removed (if that what you mean when you say the "terminal buss is bonded".)

The interesting point about this question, to me, is that the panel tends to be manufactured with the grounded conductor terminal strip electrically bolted, welded, rivetted or otherwise attached to the enclosure. There is no MBJ to remove without remanufacturing the enclosure.

 

[al hildenbrand]

Here is a very brief and basic history of grounding and the NEC:

1918 ? First code edition prohibiting the grounded circuit conductor to be bonded to equipment ? Rule 15A.

Nice reference, Bryan.

 

[ericsherman37]

Karl Riley once posted that paralleled conductors goes back to 1934.

I can believe that. It was probably just as hard to pull one run of giant conductors in 1934 as it is now.

 

[bphgravity]

Nice reference, Bryan.

I have attached a scan of that wording in the 1918 in case you guys want to see it for yourselves...

 

[al hildenbrand]

I have attached a scan of that wording in the 1918 in case you guys want to see it for yourselves...

While you were doing that, I was typing:

1918 NEC
Class C
Inside Work
All Systems and Voltages
General Rules
15A. Method of Grounding, when Protective Grounding is Required.
a.
.
.
Ground Conductors
m. For the frames of electrical equipment the current capacity of the ground conductor must not be less than that provided by copper wire of the size indicated in the following table.

With portable equipment protected by fuses not greater than 15 amperes, No. 14 ground wire may be used.

Capacity of nearest cut-out .................Required size of
protecting the equipment. ....................ground conductor.

0 to 100 amperes .............................. No. 10 B. & S. gage
101 to 200 ... " ................................. No. 6 ..... " ....... "
201 to 500 ... " ................................. No. 4 ..... " ....... "
501 amperes and above ...................... No. 2 ..... " ....... "

The grounded circuit wires must not be used as ground wire for equipment, etc., and ground conductors from equipment, etc., must not be connected to grounded circuit wires.