OT: Lightning surges

Discussion in 'rec.audio.pro' started by Jay Levitt, Aug 5, 2003.

  1. Scott Dorsey

    Scott Dorsey Guest

    Re: Lightning surges

    Dale Farmer <Dale@cybercom.net> wrote:
    >But when the surge from the lightning bolt reaches the drip loop at the house,
    >the curves and loops would 'confuse' it. ( hand waving a lot of science I never
    >
    >really understood anyway. ) and it would keep going in a straight line and blast
    >
    >into the side of the house, where the anchor bolt was attached to the structure
    >of the house.


    That loop forms an inductor, so it has a high impedance at high frequencies.
    Remember we're talking about stuff in the MHz range here. So the air has a
    lower impedance than the cable does and the current goes through the air
    instead.

    This is why we put a loop at the bottom of the antenna cables, to make
    the impedance to a pulse going into the receiver much higher and encourage
    the current to take another path.

    > What these protection devices do is protect your stuff from the lightning
    >strike that hits a little bit further away. You are at the mercy of the power
    >companies routing scheme there. And they are not going to change it for
    >your convenience. To really protect yourself the best, go to a building that
    >is in close enough to the city where all the utilities are buried.


    That doesn't guarantee anything, since lightning strikes to the ground can
    still induce big ground currents as well as inducing trash in buried conduit
    lines. It reduces the chances, but it doesn't eliminate it.

    The good news is that your panel actually acts as a surge suppressor; anything
    over around 6 KV will arc directly across the panel. So when we build surge
    suppression into power supplies, we don't really have to worry about anything
    over 6 KV.
    --scott
    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  2. ScotFraser

    ScotFraser Guest

    << You can get air powered
    palm nailers that will take a #6 8' copper rod and put it 7' 11" into the
    ground in about 15 seconds. I think that's the thing that scares most
    people from doing their own grounding work. Trying to drive the rod in.
    Short work with the right tools. >>

    Not where I live. There's solid rock about 4 feet down. Both studio ground rods
    I've installed over the years just stopped right there & the biggest sledges in
    the hands of the strongest guys on site just couldn't get it any further, while
    completely mushrooming the top. So that's where we cut it off.


    Scott Fraser
  3. Stephen Sank

    Stephen Sank Guest

    Re: Lightning surges

    OK, two questions-
    1) Isn't there a heavy grounding wire to earth at each utility pole? If
    not, why not?
    2) In a breaker panel, every one I have seen has basically two overlaping
    "trees" of copper, so that the two phases of 240v are within no more than
    1.5 inches for quite a lot of surface area. Isn't air dielectric strength
    about 1" per KV? Would that not make the panel a 1.5kv surge arrestor?

    --
    Stephen Sank, Owner & Ribbon Mic Restorer
    Talking Dog Transducer Company
    http://stephensank.com
    5517 Carmelita Drive N.E.
    Albuquerque, New Mexico [87111]
    505-332-0336
    Auth. Nakamichi & McIntosh servicer
    Payments preferred through Paypal.com
    "Scott Dorsey" <kludge@panix.com> wrote in message
    news:bgrel7$m4d$1@panix2.panix.com...
    > Dale Farmer <Dale@cybercom.net> wrote:
    > >But when the surge from the lightning bolt reaches the drip loop at the

    house,
    > >the curves and loops would 'confuse' it. ( hand waving a lot of science

    I never
    > >
    > >really understood anyway. ) and it would keep going in a straight line

    and blast
    > >
    > >into the side of the house, where the anchor bolt was attached to the

    structure
    > >of the house.

    >
    > That loop forms an inductor, so it has a high impedance at high

    frequencies.
    > Remember we're talking about stuff in the MHz range here. So the air has

    a
    > lower impedance than the cable does and the current goes through the air
    > instead.
    >
    > This is why we put a loop at the bottom of the antenna cables, to make
    > the impedance to a pulse going into the receiver much higher and encourage
    > the current to take another path.
    >
    > > What these protection devices do is protect your stuff from the

    lightning
    > >strike that hits a little bit further away. You are at the mercy of the

    power
    > >companies routing scheme there. And they are not going to change it for
    > >your convenience. To really protect yourself the best, go to a building

    that
    > >is in close enough to the city where all the utilities are buried.

    >
    > That doesn't guarantee anything, since lightning strikes to the ground can
    > still induce big ground currents as well as inducing trash in buried

    conduit
    > lines. It reduces the chances, but it doesn't eliminate it.
    >
    > The good news is that your panel actually acts as a surge suppressor;

    anything
    > over around 6 KV will arc directly across the panel. So when we build

    surge
    > suppression into power supplies, we don't really have to worry about

    anything
    > over 6 KV.
    > --scott
    > --
    > "C'est un Nagra. C'est suisse, et tres, tres precis."
  4. Jay Levitt

    Jay Levitt Guest

    In article <bgq0c0$lt0$1@panix2.panix.com>, kludge@panix.com says...
    > Ground impedance at very high frequencies is a big issue, which is why
    > the ground wire has to go from the panel straight to the rod without
    > any loops or kinks along the way. Lightning is a very fast risetime
    > pulse, so you need to think about stuff in the MHz region and not just
    > DC.


    Interesting and educational.. thanks. I realized that code is only a
    minimum standard, but hadn't thought about the vast difference in
    requirements between a safety ground and a lightning discharge.

    The ground from my panel is not via the water pipe, although (as
    mentioned elsewhere in the thread it's bonded to that, and in fact any
    gaps in that (e.g. water filter, softener) have large jumpers.

    The ground itself is a thick braided cable, 3/0 gauge if I'm reading the
    smudged printing correctly. Oddly, I only see this cable going to one
    of the two panels, and one is NOT a sub-panel of the other; perhaps the
    ground is tied between them with regular Romex? These are 200-amp
    panels, FWIW.

    The other bad part is that the ground cable runs at LEAST 30 feet before
    disappearing into a crawlspace. That doesn't seem like a good thing. I
    suspect that this ground wire was not redone when the house was rewired,
    so it could be as old as 1970, when the house was first wired (it used
    to be a carriage house). Heck, it could be going nowhere at all
    anymore.

    Interestingly, nothing in my studio seems to have been damaged. I
    assumed that was because of the Equitech isolation panel, but perhaps
    it's actually because the studio has its own ground rod, which is much
    more likely to be done correctly. That's all behind drywall, so I can't
    see where it goes.

    My electrician's had a family emergency, but when he gets back to work,
    maybe he can shed some (battery-powered) light on the grounding system
    here.

    --
    Jay Levitt |
    Wellesley, MA | Hi!
    Faster: jay at jay dot eff-em | Where are we going?
    http://www.jay.fm | Why am I in this handbasket?
  5. Jay Levitt

    Jay Levitt Guest

    In article <1060128926.743588@nnrp2.phx1.gblx.net>, kurt@nv.net says...
    > If the Cutler-Hammer device uses MOVs it won't provide the same level of
    > lightning protection as the SOVs used in the Delta product.


    Interesting. According to their warranty guy, it does in fact use MOVs.
    Maybe I should add a Delta, in addition to fixing the likely grounding
    problems.

    --
    Jay Levitt |
    Wellesley, MA | Hi!
    Faster: jay at jay dot eff-em | Where are we going?
    http://www.jay.fm | Why am I in this handbasket?
  6. Jay Levitt

    Jay Levitt Guest

    Re: Lightning surges

    In article <bgr09i$rta$1@bob.news.rcn.net>, rnorman@starpower.net
    says...
    > There are arc triggered breakers that see a "serious" drain on a system,
    > like a unit frying, and do their job of breaking. Simple replacements for
    > the panel, and although I think it would work for outside events, it's
    > principally designed to stop arc from dangerous internal circuits. I don't
    > know what it would do if it saw too much current coming in.


    If these are what I'm thinking of, they are actually now required for
    bedrooms as of 2002 or 2003. The electrician and I discussed installing
    them in 2001 when we renovated, but at that point he felt they were
    somewhat new, tripped way too easily, and that I shouldn't be a guinea
    pig - better to wait for the second generation of equipment once
    everyone else started installing these things en masse.

    > Plus, were you home when this happened? Do you know how close the strike
    > was? Even some of our household equipment and computers and such are
    > effected by strikes that can set off a local micro "EMP" burst from 70
    > million volts coming close. This would certainly bypass any electronics
    > used to monitor/condition/interrupt the power as it's a physical phenomena
    > not reduced to using wires.


    I wasn't home. I didn't see any trees down near me. In fact, as
    thunderstorms go, this seemed pretty tame. When I lived in Northern
    Virginia, the forecast every day from May to October was "hot, hazy,
    humid, chance of thundershowers", and we had some doozies, yet I never
    lost a single piece of equipment. In New England we get maybe a dozen
    storms a season, and here I have things frying left and right... that
    was one reason I called the power company. I figured maybe they had
    received multiple reports from customers, but no.

    > So I'd suggest that you find someone at the power company who will
    > come over and take a look at what you're running, give him any documentation
    > of what's been happening, and I'll bet somebody will get the grid right.


    Not a bad idea at all, once I straighten out the questionable grounding.
    Wellesley has its own tiny power company, and I've talked to their
    engineer on a few occasions for other reasons (most recently to figure
    out why my lights were dimming on a 400-amp service when a 150A-LRA air
    conditioner kicks in. Never did figure that out, but now I'm on my own
    personal transformer secondary...)

    --
    Jay Levitt |
    Wellesley, MA | Hi!
    Faster: jay at jay dot eff-em | Where are we going?
    http://www.jay.fm | Why am I in this handbasket?
  7. Jay Levitt

    Jay Levitt Guest

    In article <bgr1pn$202$1@bob.news.rcn.net>, rnorman@starpower.net
    says...
    > What type of location do you live at? I'm about as high here (sea level
    > wise, you smart asses) as any house around for about 2 miles, that being I'm
    > well over most everything else around my area and nothing higher for a
    > couple of miles around.


    Not here. Wellesley is suburban, about 13 miles from Boston. It's
    hilly, and I am up a bit from my street, but my roofline is about 20
    feet lower than the house next door.

    The service is underground on the property, but there are poles on the
    street; I'm not sure if those are just phone and TV, or if the
    electricity is also run there. There's one of those big canister
    transformers on the pole, so unless those are also used in low-power
    transmission, I'd guess that's the power line too.

    --
    Jay Levitt |
    Wellesley, MA | Hi!
    Faster: jay at jay dot eff-em | Where are we going?
    http://www.jay.fm | Why am I in this handbasket?
  8. Scott Dorsey

    Scott Dorsey Guest

    ScotFraser <scotfraser@aol.com> wrote:
    ><< You can get air powered
    >palm nailers that will take a #6 8' copper rod and put it 7' 11" into the
    >ground in about 15 seconds. I think that's the thing that scares most
    >people from doing their own grounding work. Trying to drive the rod in.
    >Short work with the right tools. >>
    >
    >Not where I live. There's solid rock about 4 feet down. Both studio ground rods
    >I've installed over the years just stopped right there & the biggest sledges in
    >the hands of the strongest guys on site just couldn't get it any further, while
    >completely mushrooming the top. So that's where we cut it off.


    In places like this, sometimes burying ground systems inside cement slabs
    can be a good solution. Cement is pretty conductive, and you can have a
    very large surface area between the cement and the surrounding soil for
    a good solid ground.

    I also strongly recommend a percussion drill for putting ground rods in.
    MUCH easier than a sledge in hard ground, especially if you have to put
    dozens of rods in for an antenna system.
    --scott
    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  9. Scott Dorsey

    Scott Dorsey Guest

    Re: Lightning surges

    Stephen Sank <bk11@thuntek.net> wrote:
    >OK, two questions-
    >1) Isn't there a heavy grounding wire to earth at each utility pole? If
    >not, why not?


    There are grounding wires at each point where there are lightning arrestors.
    You do not want to ground the neutral all over the place or you will create
    ground loops.

    >2) In a breaker panel, every one I have seen has basically two overlaping
    >"trees" of copper, so that the two phases of 240v are within no more than
    >1.5 inches for quite a lot of surface area. Isn't air dielectric strength
    >about 1" per KV? Would that not make the panel a 1.5kv surge arrestor?


    It comes in around 6 KV between the individual phase bars on most designs.
    Dielectric strength of air is lower than that, I believe.
    --scott


    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  10. Scott Dorsey

    Scott Dorsey Guest

    Jay Levitt <jay+news@jay.fm> wrote:
    >
    >The service is underground on the property, but there are poles on the
    >street; I'm not sure if those are just phone and TV, or if the
    >electricity is also run there. There's one of those big canister
    >transformers on the pole, so unless those are also used in low-power
    >transmission, I'd guess that's the power line too.


    Okay, on the top of the pole is a crossbar with three uninsulated
    aluminum wires. That's the 3KV feeder line.

    Below that you'll see three uninsulated wires, or sometimes a bundle
    of three insulated wires, attached to the pole with no crossbar. That
    is 120/240V.

    If you look at the transformers, you'll find they are between the 3KV
    lines and the 120/240V lines. And you'll see taps from the 120/240V
    to individual drops to houses.

    Below the power lines on the pole you'll see phone lines, which are
    big and thick and black and very different-looking than the power
    lines. They have long and round metal cans for junctions and splices
    occasionally along the line. Sometimes you will see short squat silver
    metal cans for junctions in GTE-land, bolted to poles.

    The cable TV line is even lower than that. Depending on where you
    are, it can be one or two big thick black cables, sometimes with
    helical grooves on the outside. The TV backbone is either hardline
    or Heliax material depending on where you are, but you can tell the
    difference between it and the phone stuff because the junction boxes
    are very different.

    All this stuff is probably illegal for me to tell you under the new
    anti-terrorism laws, but it's lots of fun to walk around town looking
    at poles.
    --scott


    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  11. Re: Lightning surges

    On Wed, 6 Aug 2003 15:50:53 -0600, "Stephen Sank" <bk11@thuntek.net>
    wrote:

    > Isn't air dielectric strength
    >about 1" per KV? Would that not make the panel a 1.5kv surge arrestor?


    Auto ignitions fire at 12 to 20 KV, so the air in distributors,
    etc, must withstand much more. Looking at a list of insulators,
    puncture voltage expressed in volts per mil (.001") varies from
    40 (porcelain!?) to 5600 (mica). Air is listed with no value
    given.

    Of course, I have been wrong a lot today.

    Chris Hornbeck,

    But I'd be offended if the listener wanted to undo something that I had
    done deliberately. Not offended enough to buy the record back, mind you...
    --scott
  12. Mike Rivers

    Mike Rivers Guest

    Re: Lightning surges

    In article <MPG.199b4716641401b09899ef@news-east.giganews.com> jay+news@jay.fm writes:

    > When I lived in Northern
    > Virginia, the forecast every day from May to October was "hot, hazy,
    > humid, chance of thundershowers", and we had some doozies, yet I never
    > lost a single piece of equipment.


    That's where I am, that's what the forecast is, and that's what we
    get. I lost a gutter once, but that was because a tree fell on it.



    --
    I'm really Mike Rivers - (mrivers@d-and-d.com)
  13. Scott Dorsey

    Scott Dorsey Guest

    Jay Levitt <jay+news@jay.fm> wrote:
    >
    >The ground itself is a thick braided cable, 3/0 gauge if I'm reading the
    >smudged printing correctly. Oddly, I only see this cable going to one
    >of the two panels, and one is NOT a sub-panel of the other; perhaps the
    >ground is tied between them with regular Romex? These are 200-amp
    >panels, FWIW.


    The code says that each individual service needs to be grounded, so that
    second panel should have a connection to a ground. Pull the cover off
    and look inside and see if it doesn't.

    It might be done with insulated wire, if the installing electrician had
    some lying around, but that is not necessary or useful and costs more.

    >The other bad part is that the ground cable runs at LEAST 30 feet before
    >disappearing into a crawlspace. That doesn't seem like a good thing. I
    >suspect that this ground wire was not redone when the house was rewired,
    >so it could be as old as 1970, when the house was first wired (it used
    >to be a carriage house). Heck, it could be going nowhere at all
    >anymore.


    The code says this is okay, as long as "the ground electrode is as near
    as practicable to and preferably in the same area as the grounding conductor
    connection to the system" (250-26C).

    >Interestingly, nothing in my studio seems to have been damaged. I
    >assumed that was because of the Equitech isolation panel, but perhaps
    >it's actually because the studio has its own ground rod, which is much
    >more likely to be done correctly. That's all behind drywall, so I can't
    >see where it goes.


    The isolation systems provide some isolation from trash on the power
    lines, but they don't do anything about polluted grounds.

    Does the studio have a seperate service? If so, it should have an individual
    ground.

    >My electrician's had a family emergency, but when he gets back to work,
    >maybe he can shed some (battery-powered) light on the grounding system
    >here.


    Go to the bookstore and get a copy of the NEC. It's lots of fun to try
    and figure out.
    --scott

    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  14. Jay Levitt

    Jay Levitt Guest

    In article <bgtugp$21l$1@panix2.panix.com>, kludge@panix.com says...
    > Jay Levitt <jay+news@jay.fm> wrote:
    > >
    > >The ground itself is a thick braided cable, 3/0 gauge if I'm reading the
    > >smudged printing correctly. Oddly, I only see this cable going to one
    > >of the two panels, and one is NOT a sub-panel of the other; perhaps the
    > >ground is tied between them with regular Romex? These are 200-amp
    > >panels, FWIW.

    >
    > The code says that each individual service needs to be grounded, so that
    > second panel should have a connection to a ground. Pull the cover off
    > and look inside and see if it doesn't.


    I actually need to pull the cover off to take photos for Cutler-Hammer
    anyway. I presume that this is the sort of operation I'd want to shut
    the main power off to do...? I worry about the (metal) panel brushing
    against live wires, etc. as I remove it.

    > >The other bad part is that the ground cable runs at LEAST 30 feet before
    > >disappearing into a crawlspace. That doesn't seem like a good thing. I
    > >suspect that this ground wire was not redone when the house was rewired,
    > >so it could be as old as 1970, when the house was first wired (it used
    > >to be a carriage house). Heck, it could be going nowhere at all
    > >anymore.

    >
    > The code says this is okay, as long as "the ground electrode is as near
    > as practicable to and preferably in the same area as the grounding conductor
    > connection to the system" (250-26C).


    I figured it was OK for code, but presumably bad for lightning
    discharge, yes?

    > >Interestingly, nothing in my studio seems to have been damaged. I
    > >assumed that was because of the Equitech isolation panel, but perhaps
    > >it's actually because the studio has its own ground rod, which is much
    > >more likely to be done correctly. That's all behind drywall, so I can't
    > >see where it goes.

    >
    > The isolation systems provide some isolation from trash on the power
    > lines, but they don't do anything about polluted grounds.


    Is that true even for the balanced power systems?

    > Does the studio have a seperate service? If so, it should have an individual
    > ground.


    Nope, it doesn't - the Equitech panel is run off a 70A breaker on a
    nearby sub-panel. However, the design for the studio specified a
    separate, way-the-hell-oversized ground for audio reasons.


    > Go to the bookstore and get a copy of the NEC. It's lots of fun to try
    > and figure out.


    I'd rather get a hundred thousand paper cuts on my face...

    --
    Jay Levitt |
    Wellesley, MA | Hi!
    Faster: jay at jay dot eff-em | Where are we going?
    http://www.jay.fm | Why am I in this handbasket?
  15. Scott Dorsey

    Scott Dorsey Guest

    Jay Levitt <jay+news@jay.fm> wrote:
    >
    >I actually need to pull the cover off to take photos for Cutler-Hammer
    >anyway. I presume that this is the sort of operation I'd want to shut
    >the main power off to do...? I worry about the (metal) panel brushing
    >against live wires, etc. as I remove it.


    You probably should. I've never done it, and I'm still okay, though.
    (In fact, my house doesn't have a main shutoff... the cartridge fuses
    at the top of the panel are always live. I keep saying I'll upgrade
    the panel but frankly the old panel is fine and it's grandfathered in
    under the old code).

    Just don't touch anything live.

    >> >The other bad part is that the ground cable runs at LEAST 30 feet before
    >> >disappearing into a crawlspace. That doesn't seem like a good thing. I
    >> >suspect that this ground wire was not redone when the house was rewired,
    >> >so it could be as old as 1970, when the house was first wired (it used
    >> >to be a carriage house). Heck, it could be going nowhere at all
    >> >anymore.

    >>
    >> The code says this is okay, as long as "the ground electrode is as near
    >> as practicable to and preferably in the same area as the grounding conductor
    >> connection to the system" (250-26C).

    >
    >I figured it was OK for code, but presumably bad for lightning
    >discharge, yes?


    Right, you want as short and straight a connection as possible. In many
    installations, the main service entry point (which may or may not be the
    main panel) is located in a place specifically so it can have a good
    ground.

    >> >Interestingly, nothing in my studio seems to have been damaged. I
    >> >assumed that was because of the Equitech isolation panel, but perhaps
    >> >it's actually because the studio has its own ground rod, which is much
    >> >more likely to be done correctly. That's all behind drywall, so I can't
    >> >see where it goes.

    >>
    >> The isolation systems provide some isolation from trash on the power
    >> lines, but they don't do anything about polluted grounds.

    >
    >Is that true even for the balanced power systems?


    Yes. The balanced power buys you nothing over isolation, other than reduced
    chassis leakage. This can be a big deal with old guitar amps but most of
    the time it's no advantage. These things are much more marketing than
    substance, but they DO provide a good low-pass and good isolation on the
    line.

    >> Does the studio have a seperate service? If so, it should have an individual
    >> ground.

    >
    >Nope, it doesn't - the Equitech panel is run off a 70A breaker on a
    >nearby sub-panel. However, the design for the studio specified a
    >separate, way-the-hell-oversized ground for audio reasons.


    Wait, so the subpanel is grounded seperately? With additional lightning
    arrestors at the subpanel?

    >> Go to the bookstore and get a copy of the NEC. It's lots of fun to try
    >> and figure out.

    >
    >I'd rather get a hundred thousand paper cuts on my face...


    No, really, it's like a huge puzzle where they give you only the answers
    and you try to figure the questions out. Think of it as a game!
    --scott

    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  16. w_tom

    w_tom Guest

    Thirty feet to earth ground is fine for human safety
    requirements that concern code. But code does not establish
    requirements for transistor safety - surge protection. Thirty
    feet would be low resistance - sufficient earthing for code.
    But thirty feet would be high impedance - insufficient
    earthing for surge protection.

    Earthing for surge protection usually means both meeting and
    exceeding what code required. That connection to earth ground
    must be less than 10 feet, no splices, no sharp bends, not
    bundled with other wires, etc.

    Furthermore, any other utility that enters that same "other
    service" area must first be earthed to the same ground.
    Others call it ground bounce or earth borne surges. But an
    area with multiple earth grounds means damage from surge
    transients is possible - again a failure directly traceable to
    human failure. If cable or ethernet network wire or whatever
    does not connect to that same '10 foot distant' earth ground
    before entering that area, then surge damage such (as those
    from earth) is possible.

    Again, none of this is addressed by code because code only
    addresses human safety issues. Owner is concerned with human
    safety and electronic safety meaning that owner earth in
    excess of what code requires - especially if the facility has
    separate AC mains service and therefore separate single point
    grounds.


    Scott Dorsey wrote:
    > ...
    > The code says that each individual service needs to be grounded, so
    > that second panel should have a connection to a ground. Pull the
    > cover off and look inside and see if it doesn't.
    >
    > It might be done with insulated wire, if the installing electrician
    > had some lying around, but that is not necessary or useful and
    > costs more.
    >
    >> The other bad part is that the ground cable runs at LEAST 30
    >> feet before disappearing into a crawlspace. That doesn't seem
    >> like a good thing. I suspect that this ground wire was not
    >> redone when the house was rewired, so it could be as old as
    >> 1970, when the house was first wired (it used to be a carriage
    >> house). Heck, it could be going nowhere at all anymore.

    >
    > The code says this is okay, as long as "the ground electrode is
    > as near as practicable to and preferably in the same area as the
    > grounding conductor connection to the system" (250-26C).
    > ...
  17. Jay Levitt

    Jay Levitt Guest

    >
    > >> Does the studio have a seperate service? If so, it should have an individual
    > >> ground.

    > >
    > >Nope, it doesn't - the Equitech panel is run off a 70A breaker on a
    > >nearby sub-panel. However, the design for the studio specified a
    > >separate, way-the-hell-oversized ground for audio reasons.

    >
    > Wait, so the subpanel is grounded seperately? With additional lightning
    > arrestors at the subpanel?


    According to the plans, there should be a separate 4-gauge ground cable
    running from the Equitech to the main ground rod. I seem to recall the
    electrician telling me he just sunk a separate ground rod to keep the
    run short. There are no separate lightning arrestors on the Equitech,
    but it is downstream of the main panel which has them...

    ----------------- ---------------- ----------------
    | 200A Panel A |-----|100A sub-panel|---|Equitech panel|
    -|w/suppressor|-- ---------------- ----------------
    | |
    | really long ground braid | ground #2
    V V

    -----------------
    | 200A Panel B |
    -|w/suppressor|--
    |
    |
    V

    --
    Jay Levitt |
    Wellesley, MA | Hi!
    Faster: jay at jay dot eff-em | Where are we going?
    http://www.jay.fm | Why am I in this handbasket?
  18. Re: Lightning surges

    Just put the A/C on the other rail and the light problem should go away,
    BUT, don't do it if your room is going to be on the same rail. In fact,
    plan with your electrician to put all the noisy motor stuff, A/C,
    Freezers/refrigerators, humidifiers, sump pumps, etc., either on one rail or
    run a sub-panel that handles those pieces of equipment.

    The problems with most grids is that the most current draw is in the newer
    sections where houses typically have 200 amp services and actually USE them,
    plus a lot of housing tracts are surrounded by industrialized areas. I
    upgraded our box to 200 amps and absolutely use it, but that's because I'm
    in an old section of town (75 year old house) that has no air ducts to run
    central air and heat. When I was doing the design for adding the woodshop
    and the pool heater/filter, I found only ONE circuit running that was
    drawing more than 10 amps (the pool filter and some stuff). Everything else
    was pretty much pulling maybe 2 amps, but I didn't check when all the A/C
    units were fired up.

    The point being that all the older housing was designed with maybe 60 amp
    panels, a few light circuits, MAYBE an electric range and MAYBE an electric
    clothes dryer, but not much more than that. So the grid in the old sections
    of town usually represents THAT design rather than the design of today where
    someone may do Arc welding for a hobby, or have 4 computers running along
    with at least one TV all day. Then there's the microwave, a toaster oven,
    A/C, you name it. The grid's ability to put the electricity over it is
    fine, but it's the inability of the grid to handle large system draws, which
    is why I was lucky enough to be living in an area where my friend was
    responsible for doing the grid redesign. Once his design was implemented,
    most of my apparent problems went away. Not saying I don't have a small
    ground loop here or there, but they are defeatable if I wish to take a
    couple of minutes. But to prove the point, about two years after I was
    basking in my luck of great electrical supply, Pepco came over and swapped
    out my old analog meter for a new digitally probed unit (honesly why can't
    they just use FTP?) which wasn't seated quite right and I raised a stink
    about it. After some hemming and hawing, they finally came over, yanked out
    the new meter and simply seated it better and I've been back to nice clean
    power ever since.

    Your problem doesn't seem likely to go away just from some of your efforts.
    This sounds like you're going to need to get the power company involved to
    sort the problems out. And they aren't likely to want to accomodate you if
    it means they have to put out lots of money to redesign and implement their
    grids.

    --


    Roger W. Norman
    SirMusic Studio
    Roger@SirMusicStudio.com
    301-585-4681




    "Jay Levitt" <jay+news@jay.fm> wrote in message
    news:MPG.199b4716641401b09899ef@news-east.giganews.com...
    > In article <bgr09i$rta$1@bob.news.rcn.net>, rnorman@starpower.net
    > says...
    > > There are arc triggered breakers that see a "serious" drain on a system,
    > > like a unit frying, and do their job of breaking. Simple replacements

    for
    > > the panel, and although I think it would work for outside events, it's
    > > principally designed to stop arc from dangerous internal circuits. I

    don't
    > > know what it would do if it saw too much current coming in.

    >
    > If these are what I'm thinking of, they are actually now required for
    > bedrooms as of 2002 or 2003. The electrician and I discussed installing
    > them in 2001 when we renovated, but at that point he felt they were
    > somewhat new, tripped way too easily, and that I shouldn't be a guinea
    > pig - better to wait for the second generation of equipment once
    > everyone else started installing these things en masse.
    >
    > > Plus, were you home when this happened? Do you know how close the

    strike
    > > was? Even some of our household equipment and computers and such are
    > > effected by strikes that can set off a local micro "EMP" burst from 70
    > > million volts coming close. This would certainly bypass any electronics
    > > used to monitor/condition/interrupt the power as it's a physical

    phenomena
    > > not reduced to using wires.

    >
    > I wasn't home. I didn't see any trees down near me. In fact, as
    > thunderstorms go, this seemed pretty tame. When I lived in Northern
    > Virginia, the forecast every day from May to October was "hot, hazy,
    > humid, chance of thundershowers", and we had some doozies, yet I never
    > lost a single piece of equipment. In New England we get maybe a dozen
    > storms a season, and here I have things frying left and right... that
    > was one reason I called the power company. I figured maybe they had
    > received multiple reports from customers, but no.
    >
    > > So I'd suggest that you find someone at the power company who will
    > > come over and take a look at what you're running, give him any

    documentation
    > > of what's been happening, and I'll bet somebody will get the grid right.

    >
    > Not a bad idea at all, once I straighten out the questionable grounding.
    > Wellesley has its own tiny power company, and I've talked to their
    > engineer on a few occasions for other reasons (most recently to figure
    > out why my lights were dimming on a 400-amp service when a 150A-LRA air
    > conditioner kicks in. Never did figure that out, but now I'm on my own
    > personal transformer secondary...)
    >
    > --
    > Jay Levitt |
    > Wellesley, MA | Hi!
    > Faster: jay at jay dot eff-em | Where are we going?
    > http://www.jay.fm | Why am I in this handbasket?
  19. Re: Lightning surges

    Interestingly enough, most of the storms seem to come right down the Potomac
    river, and generally stay on the low side of DC (Virginia side), but when I
    do get hit, it's likely to make the house move. Living at one of the
    highest places around, it's always bothered me somewhat, but my fears have
    been only that so far. Still, enough come through to cause problems, and I
    still proactively shut down the studio and the computers when my dog shows
    up in the studio under my desk. That means he knows something I don't, so
    it's time to batten down the hatches! <g> He hears storms that are out near
    Leesburg, which is a good 35 miles from here.

    --


    Roger W. Norman
    SirMusic Studio
    Roger@SirMusicStudio.com
    301-585-4681




    "Mike Rivers" <mrivers@d-and-d.com> wrote in message
    news:znr1060216687k@trad...
    >
    > In article <MPG.199b4716641401b09899ef@news-east.giganews.com>

    jay+news@jay.fm writes:
    >
    > > When I lived in Northern
    > > Virginia, the forecast every day from May to October was "hot, hazy,
    > > humid, chance of thundershowers", and we had some doozies, yet I never
    > > lost a single piece of equipment.

    >
    > That's where I am, that's what the forecast is, and that's what we
    > get. I lost a gutter once, but that was because a tree fell on it.
    >
    >
    >
    > --
    > I'm really Mike Rivers - (mrivers@d-and-d.com)
  20. And that's why I am taking the electrical and re-doing it, which, of course,
    puts the patio thing on a slower track because I have to carefully dig up
    all that 6/2 UFB cable and re-do the circuits without touching the shell of
    the pool. Admittedly, a non conducting mouting surface, outdoor
    weatherproofed boxes, GFI breakered power and a properly run 8' #6 ground
    rod should do the job, but not the way NEC states the job should be done.

    Looks like I won't get this yard done until we're into the fall, dammit. Oh
    well, maybe we'll get a couple of bushels of crabs and have a crab feast
    instead. Who the hell wants to party in the heat of August with a pool and
    A/C going in the studio? <g>

    Of course, if you want to stop by and help on one of your weekends up here,
    I'll be glad to provide all the comforts like meals, beers, a swim in the
    pool, bathtub spa (if you need it). Know anything about doing brick mason
    work or even how to mix mortar to the right consistency? <g>

    --


    Roger W. Norman
    SirMusic Studio
    Roger@SirMusicStudio.com
    301-585-4681




    "Scott Dorsey" <kludge@panix.com> wrote in message
    news:bgr6dm$ngk$1@panix2.panix.com...
    > Roger W. Norman <rnorman@starpower.net> wrote:
    > >
    > >Now I'm a kinda hands on guy, so when I saw this I called my Pepco friend
    > >back over, and I've since redone the electrical to meet code even if an
    > >inspector isn't coming over. But in some cases, maybe an inspector is

    the
    > >best way to get the local utility to do it's job. If not, prepare to

    learn
    > >something about electricity and then make some design changes. The

    concept
    > >of a field wide grounding system isn't that big of a deal. It takes less
    > >time than the damage that can ensue costs.

    >
    > A lot of electricians just plain don't know the code outside the little
    > area where they normally work. The code is big and it's pretty dense,
    > and it can be difficult to read because it explains what to do but never
    > why it's necessary.
    >
    > If he's never looked at the swimming pool section of the code, he might
    > very well not know that this is a bad thing to do.
    >
    > I know that I have had a lot of nightmares dealing with licensed

    electricians
    > at festival gigs and film shoots who have never used remote generators and
    > don't know about the varied and unusual grounding regulations for remote

    power
    > systems. (Regulations that do make sense if you sit down and really think
    > about them, but which can seem alarming if you don't. I had a lot of fun
    > explaining to one fellow at the Potomac festival last year that his

    generator
    > had to run ungrounded and that tying it to a ground rod was a code

    violation,
    > but that if it was connected to a fixed trailer it would have to be

    grounded).
    > --scott
    >
    > --
    > "C'est un Nagra. C'est suisse, et tres, tres precis."

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