Station Earth / RF Earth for shack on 2nd / 3rd floor

Station Earth / RF Earth for shack on 2nd / 3rd floor

Post by J. McLaughli » Sat, 04 Jan 2003 11:03:17

Dear Dan and other UK amateurs:
    Wow.  I always thought that the electrical distribution system in UK
was designed with an emphasis on low cost - you have confirmed it.  I
shall add to my safety lectures how things are done in UK.
    My suspicions were aroused when the purchase of an electrical
appliance in the UK did not include a plug.  One went to a separate
store for a plug.  I just put it off to heightened liability concerns
with some small justification being more than one set of socket
standards.
    The only justification for the existence of a profession is the
protection of the public.  I make sure that my students understand the
scheme used in NA for protecting people and property.  Contrasting the
requirements of the NEC (not the antenna one) with the scheme you are
subjected to is bound to impress them more then just discussing the NEC.
    Thanks for the explanation.  Wow!
        73   Mac,   N8TT

--
J. Mc Laughlin  -  Michigan USA

 
 
 

Station Earth / RF Earth for shack on 2nd / 3rd floor

Post by r.drin » Mon, 06 Jan 2003 06:22:57


Ian I suggest you have a look around your incomer installation and see if
there is a
notice identifying it as PME first. Also examine your installation and try
and identify
the main earthing arangement.
Another person who  has had a disagreement with the electricity supply
company over
PME was "Professor Peter Felgett" one of the co-inventers of the Amisonic
surround sound system.
The row was detailed in the New Scientist magazine last year.



> >There seems to be some confusion about PME, and circuit breakers. (UK
only)
> >During the post world war 2 building boom there was a need to reduce the
> >cost of housing construction. PME  could help, by allowing a reduction
> >in the number of cable cores that needed to be run in a domestic
electrical
> >installation. The neutral and earth being the same conductor.
> <SNIP>

> I have a similar kind of installation with a few minor differences. My
> mains supply is delivered via overhead lines. I get one phase, neutral
> and earth delivered in separate single core conductors from the
> nearest distribution transformer (about 1km distant). I have concerns
> regarding the earth and reckon it is simply a connection to neutral at
> the distribution transformer. What should I do about earthing gear in
> the shack? I don't have any kind of circuit breaker, just fuses and a
> normal mains switch.

> Ian

> --
> Ian Pollard//Wooler//Northumberland//UK


 
 
 

Station Earth / RF Earth for shack on 2nd / 3rd floor

Post by r.drin » Wed, 08 Jan 2003 06:54:42

Hello Ian if you want to do away with PME you can disconnect the PME earth
wire on the earth bar in your consumer unit after you have replaced it with
a standard earth arrangement.
If you still have fuses you can usually find a direct plug in miniature
circuit breaker for each fuse that will tighten up the overcurrent
protection. You can run you own earth continuity conductor from your earth
bar in the consumer unit to a new earth electrode. I should not have to tell
you how to get a good low resistance earth electrode connection. Don't
forget to label it "Main Earth connection do not remove". If you can it
would be a good idea to install a suitably rated  30mA instantaneous RCCD in
any circuits that feed sockets,  with a 100mA 1second delay RCCD
on the main feeder to the consumer unit. Again rated for the full load of
the consumer unit, If you only can install one on the feeder make it a 30mA
instantaneous RCCD,They give you protection against electric shock but you
can get some nuisance tripping. Current IEE regulations are all about
sizing cable and earth conductors, to ensure in a fault situation,
sufficient current flows to trip the safety devices Evershed and Vignoles
(Megger) do a very good pocket guide book to electricity testing. Finally
many electrical wholesalers in the UK will hire out the line earth loop
impedance testers
that you need to ensure the line earth and neutral earth loops have a
sufficiently low impedance.
You may also be able to hire a 4 contact earth electrode impedance tester.
RayD



> >There seems to be some confusion about PME, and circuit breakers. (UK
only)
> >During the post world war 2 building boom there was a need to reduce the
> >cost of housing construction. PME  could help, by allowing a reduction
> >in the number of cable cores that needed to be run in a domestic
electrical
> >installation. The neutral and earth being the same conductor.
> <SNIP>

> I have a similar kind of installation with a few minor differences. My
> mains supply is delivered via overhead lines. I get one phase, neutral
> and earth delivered in separate single core conductors from the
> nearest distribution transformer (about 1km distant). I have concerns
> regarding the earth and reckon it is simply a connection to neutral at
> the distribution transformer. What should I do about earthing gear in
> the shack? I don't have any kind of circuit breaker, just fuses and a
> normal mains switch.

> Ian

> --
> Ian Pollard//Wooler//Northumberland//UK


 
 
 

Station Earth / RF Earth for shack on 2nd / 3rd floor

Post by r.drin » Wed, 08 Jan 2003 06:56:21

Gentlemen, gentlemen, with all your horror stories you will frighten Martin
in to giving up amateur radio.
We need to answer his questions, and to do that we need to define the
problems, as I see it they are
1 Is his supply PME, and if so what is to be done about it, and what is to
be done to separate the RF noise from the mains, and the mains earth.
2 The RF earth lead could be a resonant length on some bands giving high or
low impedances and voltages, what can be done about it, or even does he need
an RF earth connection at all. What can he do to ensure that no high voltage
RF conductors can come into contact with anyone.
3 What can he do about lightening protection.
4 What can he do to ensure he does not create TVI or BCI to his neighbours.
All of the forgoing questions can be answered, but Martin deeds to supply a
few more details about
his home and surroundings.
some of the questions are as follows:
Is he in the UK if not where is he.
What kind of electricity supply does he have, overhead or underground
feeder, is it  PME,
Is his building a high rise block, if not what type/height is it.
Where are the antenna's going to be mounted, on his building or on separate
self supporting structures or other buildings.
Are the antenna's and feeders going to be coax, balanced, or end, fed. Are
they resonant, broadband, or tunable.
Can he use an RF earth or counterpoise.
Martin wants the safest, cost affective solutions for his installation. All
of the problems and hazards are curable with a little care, and he will
still have a suitable and sensitive installation.
I recommend he obtains a copy of the RSGB book "HF antenna collection" which
has the Peter Chadwick article "the Killing ground" reproduced in it.
Another version is in the RSGB Book "The radio amateur guide to EMC.
This reply is already too long so I will put more answers regarding ELCB's
and RCCD's and PME in another email.

Quote:> Hi, and thank you for reading this.
> I am in stalling my radio station in to the small "box room" on the 2nd
> floor
> of the building and I have in the past not worried about a separate earth
> for
> the station. But as this station is going to be a more permanent
arrangement
> than my other previous locations I want to make sure that :-
> 1) the station is safe electrically. (of course the supply earth will be
> connected)
> 2) protected form static (lightening etc).
> 3) has a good RF performance. (this means low resistance earth connection)
> 4) is as clear of EMC problems as possible.

> So any one got some pointers or helpful hints on installing a separate
> station
> earth. The ground connection is easy 3 to 6 off 6' long 1" dia copper
pipes
> driven all the way in to the soil (I know it is a big is job but not
> impossible).
> The bit I am puzzling over is do I use a heavy copper strap as used on
> church
> lightening conductors to provide a common earth for every thing or just
for
> the
> static protection and then a separate heavy conductor to provide the shack
> equipment earth.
> In either case how can I ensure that the earthing does not radiate RF (I
> assume
> that making sure the aerials are correctly balanced with suitable baluns
> fitted is
> the answer here.)
> I did here about using RG8 type coax and connecting both inner and screen
> to the hardware in the ground but only connecting the shack earth buss to
> the
> inner - any thoughts on this.

> Cheers Martin

 
 
 

Station Earth / RF Earth for shack on 2nd / 3rd floor

Post by r.drin » Wed, 08 Jan 2003 07:14:23

Have a look at other news item Re PME and ELCB's, RCCD's and MCB's
RayD

> Dear Dan and other UK amateurs:
>     Wow.  I always thought that the electrical distribution system in UK
> was designed with an emphasis on low cost - you have confirmed it.  I
> shall add to my safety lectures how things are done in UK.
>     My suspicions were aroused when the purchase of an electrical
> appliance in the UK did not include a plug.  One went to a separate
> store for a plug.  I just put it off to heightened liability concerns
> with some small justification being more than one set of socket
> standards.
>     The only justification for the existence of a profession is the
> protection of the public.  I make sure that my students understand the
> scheme used in NA for protecting people and property.  Contrasting the
> requirements of the NEC (not the antenna one) with the scheme you are
> subjected to is bound to impress them more then just discussing the NEC.
>     Thanks for the explanation.  Wow!
>         73   Mac,   N8TT

> --
> J. Mc Laughlin  -  Michigan USA


 
 
 

Station Earth / RF Earth for shack on 2nd / 3rd floor

Post by Gareth Rowlan » Thu, 09 Jan 2003 06:49:50



Quote:> Finally many electrical wholesalers in the UK will hire out the line
> earth loop impedance testers that you need to ensure the line earth
> and neutral earth loops have a sufficiently low impedance.

One little point for anyone contemplating - if you have an RCD in the
mains supply, and you are hiring or buying one of these devices, do make
sure it is of the variety built to work without tripping any RCD in
circuit when testing.

The type of earth loop impedance tester that shorts half-a-cycle of
mains from live to earth is pretty good at testing for the presence
of RCDs, and if one is in circuit, not a lot else.

Does anyone know what the status is of having lighting circuits fed
through a 'main' RCD ?  There was a period in time when this was felt
to not be a quite a good idea to have a home plunged in to darkness
when a pinhole appeared in the kettle element.  

There is an interesting item on earthing power conditioners which may
be of relevance - and which includes having a 'clean earth' at:

  http://www.advance-galatrek.co.uk/lowlevel/hb/hb022.htm

73, G.

--
http://www.rat.org.uk/