D
daestrom
Guest
"Steve Alexanderson"
<Idon'tlikegreeneggsandspamIdon'tlikethemsamIamsalexanderson@cencoast.com>
wrote in message news:40f80155$1_4@newsfeed.slurp.net...
Seems quite clear to me that the ground lug is only there to provide a
grounding for wire sheathing. The NID is meant to be used for wire that has
a metallic shield -or- a non-metallic cover. When a metal shielded cable or
support wire is used, it is connected to the ground lug of the NID and the
NID lug must be grounded. But if the phone drop does *not* use a support
wire or shielded cable, there is nothing connected to the ground lug inside
the NID. If you want to ground it, you are essentially running a ground
wire to a terminal that is connected to *nothing*.
Some may argue that having a grounded lug within an inch or so of the phone
wires provides *some* kind of protection by allowing direct lighning surges
to jump the small gap. But a voltage level needed to jump such a gap would
destroy all the phones in your house. And it would be much higher than the
protection devices at the pole would allow. So such a 'gap' argument is
silly as it is no protection at all.
Grounding the NID lug is only significant *if* the incoming phone drop uses
shielded wire or support wire that needs to be grounded. They don't have
internal surge-suppression/lightning protection. The use of the ground lug
varies from one phone company to the next. It even varies within the same
service area. The NID is designed for use with either type of phone drop
(one with a metallic shield or without). But like many devices, this
'feature' (the ground lug) isn't always used. It is only there for
grounding the shield or non-circuit metallic components. If you have
unshielded, tempered phone drop, there is no non-circuit metallic components
to ground.
daestrom
<Idon'tlikegreeneggsandspamIdon'tlikethemsamIamsalexanderson@cencoast.com>
wrote in message news:40f80155$1_4@newsfeed.slurp.net...
The presence of the ground lug indicates that some type of arrester is
involved, even if it's just a gap. See
http://www.taunton.com/finehomebuilding/pdf/Lightning.pdf
He is right that his department and the NEC doesn't apply to utilities.
The
code in question is the NESC, and among its requirements is one stating
that
arresters that require grounding be grounded, and another stating that
accessible communication equipment subject to overvoltage be protected
against overvoltage.
snip
The NID (network interface device) does not have gas discharge
devices, it is strictly a disconnecting means. The telephone company
is required, if you request, an accessible Network Interface Device.
The ground wire typically only protects the enclosure or the wire
sheathing, which in this case is plastic for the NID, and
non-existent in the drop.
Seems quite clear to me that the ground lug is only there to provide a
grounding for wire sheathing. The NID is meant to be used for wire that has
a metallic shield -or- a non-metallic cover. When a metal shielded cable or
support wire is used, it is connected to the ground lug of the NID and the
NID lug must be grounded. But if the phone drop does *not* use a support
wire or shielded cable, there is nothing connected to the ground lug inside
the NID. If you want to ground it, you are essentially running a ground
wire to a terminal that is connected to *nothing*.
Some may argue that having a grounded lug within an inch or so of the phone
wires provides *some* kind of protection by allowing direct lighning surges
to jump the small gap. But a voltage level needed to jump such a gap would
destroy all the phones in your house. And it would be much higher than the
protection devices at the pole would allow. So such a 'gap' argument is
silly as it is no protection at all.
Grounding the NID lug is only significant *if* the incoming phone drop uses
shielded wire or support wire that needs to be grounded. They don't have
internal surge-suppression/lightning protection. The use of the ground lug
varies from one phone company to the next. It even varies within the same
service area. The NID is designed for use with either type of phone drop
(one with a metallic shield or without). But like many devices, this
'feature' (the ground lug) isn't always used. It is only there for
grounding the shield or non-circuit metallic components. If you have
unshielded, tempered phone drop, there is no non-circuit metallic components
to ground.
daestrom