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Posted by DIMwit on June 3, 2007, 6:33 pm
anybody ever tell you that you talk too much?
in the US we don't call it earthing; we call it grounding.
Surges can also occur phase to phase.
I need to get some aspirin.
>> Last year our HVAC repair tech recommended that we should get a surge
>> suppressor installed on our furnace/ac unit to prevent damage that
>> might be caused by power sikes or electrical storms.
>> No one else I have talked to in the neighborhood has one of these
>> things.
>
> Surges that may overwhelm protection already inside all appliances
> (including the furnace) may occur typically once every seven years. A
> number that can vary significantly even within same town due to
> variables such as geology. A survey of the neighborhood may learn
> more.
>
> Do you install a $100 protector for the furnace? Or do you install
> something so that everything - including furnace - is protected. When
> is your smoke detector most important? Maybe during events that
> create surges. What protects that smoke detector?
>
> This solution has been standard even in telephone exchanges for what
> - 100 years? Standard in commercial broadcasting, 911 emergency
> response centers, etc. In no case is a surge protector called
> protection. A surge protector is the device that 'connects to'
> protection. Protection is earth ground.
>
> Ben Franklin demonstrated the concept in 1752. Lightning obtained
> earth ground destructively via church steeples. How did Franklin
> divert a surge so that a steeple was not damaged? Lightning rod
> connected to protection. That protection is earth ground.
>
> Lightning striking a utility wire down the street can be a direct
> strike to every household appliance including furnace, smoke
> detectors, and bathroom GFCI. How is protection installed? Just like
> Franklin's lightning rod, earth a surge before it can enter the
> building. One protector connected 'less than 10 feet' to an upgraded
> single point earth ground does what your telco installs to protect
> their computer. Their computer is connected to overhead wires all
> over town. Do they put a protector adjacent to the computer? Of
> course not.
>
> Every incoming wire in every cable must connect to earth ground.
> Some cables such as cable TV and satellite dish are earthed only by a
> ground block and wire. Others, such as telephone and AC electric,
> require a protector to make a 'less than 10 foot' connection. IOW one
> 'whole house' protector for about $1 per protected appliance verses
> how much for that furnace protector?
>
> This was long. Many just have trouble learning that earthing - not
> the protector - is protection. Many assume a protector will somehow
> stop or absorb what even three miles of sky could not. And yet that
> is what the protector adjacent to the furnace would do to be useful.
> That furnace protector also does nothing for smoke detectors,
> dishwasher, or bathroom GFCIs.
>
> How to installed effective protection? First, building earthing
> must be upgraded to and exceed post 1990 NEC requirements. IOW all
> incoming utilities must be earthed to the same electrode (ground
> rod). Earthing wires to that electrode must have no sharp bends, be
> separated from other non-earthing wires, no splices, not inside
> conduit, and all meet as the same earthing electrode.
>
> Second, for utilities that require earthing via a protector,
> manufacturers with responsible names such as Square D, GE, Leviton,
> Cutler-Hammer, Intermatic, Siemens, etc manufacturer a 'whole house'
> protector. Protector must exceed 1000 joules and 50,000 amps.
> Protectors has a dedicated wire for that essential ('less than 10
> foot') earthing connection. Some are sold for less than $50.
>
> Names such as APC, Tripplite, Panamax, and Belkin are not listed.
> Their protectors don't even have a dedicated earthing wire. How would
> their products earth as Franklin demonstrated in 1752? Protectors
> without that earthing wire quietly don't claim to protect from the
> typically destructive surge - one that may overwhelm protection inside
> the furnace.
>
> Separation between the protector and furnace is part of a protection
> 'system'. But more important, distance to earth ground must be as
> short as practical. That means an earthing wire from breaker box,
> over top of a foundation, then down to an earthing electrode, is too
> long. That wire must route through the foundation and down to
> earthing electrode - short distance and no sharp bends is important.
>
> What will a protector at the furnace do? What is the shortest path
> to earth? If through a furnace, then the protector may have
> compromised protection that is already inside that furnace.
>
> Do not yet let anyone promote a protector as protection. Protection
> is earthing. A protector is simply a connection to earthing. But if
> that earthing connection is too long, then the protector may earth,
> destructively, through and adjacent electronics such as a furnace.
>
> Your telephone also needs a 'whole house' protector. Did you know
> the telco installs one for free? Why? Because a 'whole house'
> protector is so inexpensive and so effective. But again, you are
> responsible for providing earthing. Is that telco protector connected
> short to the same earthing electrode used by AC electric, cable TV,
> etc? If not, then you still do not have protection.
>
> If not obvious, most important component in this (your 'secondary')
> protection system is the quality of and short connections to a single
> point earth ground. Yes - 'secondary'. Also inspect your 'primary'
> protection:
> http://www.tvtower.com/fpl.html
>
> An industry professional demonstrates the concept in an application
> note. All incoming cables connect to a single point earthing
> (directly or via a protector) before entering the building. Surge
> protection required even on underground cables:
> http://www.erico.com/public/library/fep/technotes/tncr002.pdf
>
> A protector will only be as effective as its earth ground. We earth
> so that a destructive surge, maybe once every seven years, does not
> enter a building. Therefore protection already inside all appliances
> (and the furnace) will not be overwhelmed.
>
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