Portable Generators and Ground Rods

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Re: Portable Generators and Ground Rods

This is really good stuff. Thanks!

Hurk27 said:
And the reason the houses with a water pipe bond didn't have this problem is the water pipe is bonded at the next house which is bonded to the neutral at the next service.
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All the houses I've seen of late only have a copper pipe water supply a short distance out from the house and then it converts to PVC pipe. The mains may be PVC too. That would break the bond unless they are running a bond wire too. Of course I'm only speaking of what I've seen under construction in my immediate area.

I don't want to muck up this conversation but I thought I'd chime in with what I've observed around the San Francisco Bay Area over the past 30 years. More than forty years ago it may have been all iron pipe from house to main to house. Additionally, in my area there is currently a dielectric union at the water meter which would defeat the bonding path.

My nomenclature may clash with yours. If dielectric is not acceptable then the concept I am trying to convey is that the water meter introduces an impedance on the water line even if the water line is metal from house-to-house.

Your mileage may vary. Happy trails!

../Wayne

PS: I did a Google search for dielectric coupler water meter and here's the only good hit I got:
Subject: (Philips) Current Flow on Water Pipes Between Houses (fwd)
Date: Wed, 26 Aug 1998 063913 -0500 (CDT)
From: "Roy L. Beavers" <rbeavers@llion.org>
To: emfguru@hotmail.com
--------------------------------------------------
---------- Forwarded message ----------
Date: Wed, 26 Aug 1998 11:05:44
From: Alasdair Philips
To: "Roy L. Beavers"
Subject: Current Flow on Water Pipes Between Houses (fwd)

Roy - some comments:
>---------- Forwarded message ----------
>From: Stewart Fist
>There's been a lot of discussion recently about water pipes and
>'dielectric' unions. I must be ignorant here, or there's a
>terminological problem between Australian English and US English.
>Do people mean 'non-conductive',or are they implying inductive coupling?
>-----------------------------------------------------------------
STEWART IS CORRECT. "NON-CONDUCTIVE" IS THE TERM WHICH SHOULD BE USED.
'DIELECTRIC' MEANS "A MEASUREMENT OF THE ABILITY TO TRANSMIT ELECTRIC
EFFECTS WITHOUT CONDUCTING"! THE EFFECT IS USED IN CAPACITORS WHICH DOUBLE
THE AMOUNT THEY CAN PASS AS THE FREQUENCY DOUBLES - THEREFORE A DIELECTRIC
COUPLING ON A PIPE WOULD REJECT THE 50/60HZ BUT PASS SOME HIGH FREQUENCY
TRANSIENT SIGNALS.
------------------------------------------------------------------
>From: Envoptions@aol.com - Spark Burmaster
>Subject: SX1: Current Flow on Water Pipes Between Houses
>This is in reference to thepostings on the putting of a dielectric
>union in the water service supply pipe of a house.
>I wish to comment on these three issues.
>1) Electrical Safety
>2) Biological Issues
>3) Proper use of terms to avoid confusion.

I AGREED WITH MOST OF WHAT SPARK WROTE BUT FOUND SOME OF HIS WORDS
HAD TO BE READ MORE THAN ONCE. I WISH TO COMMENT ON SOME POINTS:

1/ SAFETY
IN MOST COUNTRIES NOW IT IS A LEGAL REQUIREMENT THAT ALL METAL PIPEWORK
WITHIN A HOUSE IS ELECTRICALLY BONDED TO THE ELECTRICAL SAFETY EARTH TO
PREVENT THE POSSIBILITY OF ELECTRIC SHOCK. IN MOST EUROPEAN COUNTRIES IT
IS NOW NO LONGER LEGAL TO RELY ON AN INCOMING WATER PIPE TO PROVIDE AN
ELECTRICAL EARTH - THIS IS BECAUSE MANY WATERS MAINS ARE BEING REPLACED
WITH PLASTIC PIPES.

THE ELECTRICAL 'EARTH' CONNECTION IS EITHER SUPPLIED BY THE ELECTRICAL
UTILITY OR IT CAN BE A SEPARATE "EARTH STAKE" IN THE GROUND WHICH HAS BEEN
TESTED FOR A LOW ELECTRICAL IMPEDANCE FOR THE ELECTRICITY (IE EFFECTIVELY
TO THE NEAREST SUBSTATION TRANSFORMER) BY DUMPING A SUBSTANTIAL CURRENT
(SEVERAL AMPS)INTO IT AND MEASURING ITS EFFECTIVE IMPEDANCE. (The tests are
usually defined in the Electrical Regulations /Codes and Annexes).

IT IS BEST THAT ALL INCOMING METAL PIPES HAVE INSULATING/NON-CONDUCTING
SECTIONS IN THEM AND ARE ONLY CONNECTED TO THE "ELECTRICAL SAFETY EARTH"
WITHIN THE HOUSE ITSELF. (TO COMPLY WITH THE REGUATIONS/CODES)

MANY/MOST UTILITIES AROUND THE WORLD SUPPLY LOW VOLTAGE AS A THREE-PHASE
PLUS NEUTRAL STAR SUPPLY WHICH HAS THE 110/230 VOLT SINGLE PHASE SUPPLIES
WHICH FEED MOST HOUSES TAKEN ACROSS ONE (VARYING from house to house)PHASE
TO NEUTRAL. IN ORDER TO HELP PREVENT LARGE "OVER-VOLTAGES" OCCURRING UNDER
FAULT CONDITIONS THEY CONNECT THE NEUTRALS ON NEIGHBOURING SUBSTATIONS
TOGETHER (THE VERY PRACTICE THAT SPARK AND KARL STATE IS A 'NO-NO' WITHIN A
BUILDING) AND THIS CAN LEAD TO LARGE (I HAVE MEASURED 384 AMPS!) NET ERROR
CURRENTS FLOWING AROUND URBAN DISTRICTS ELEVATING MAGNETIC FIELDS OVER
LARGE AREAS.

AS THE SUPPLY NETURALS ARE ALSO CONNECTED TO "GROUND" AT THE SUBSTATIONS
AND IN THE CASE OF PME (PROTECTIVE MULTIPLE EARTHING) SYSTEMS AT REGULAR
INTERVALS AROUND THE DISTRICT, THESE ERROR CURRENTS END UP ON METAL WATER
AND GAS PIPES, ENTER A HOUSE, AND RETURN OUT FROM THE HOUSE ON THE
ELECTRICITY COMPANY SUPPLIED EARTH WHICH HAS BEEN CONNECTED TO THE PIPES
INSIDE THE HOUSE AS REQUIRED BY THE REGULATIONS.

I HAVE MEASURED 43 AMPS FLOWING INTO ONE HOUSE IN THIS WAY. WHEN I CUT THE
PIPE THE VOLTAGE WAS ONLY A COUPLE OF VOLTS BETWEEN THE CUT ENDS BECAUSE
THE IMPEDANCE WAS SO LOW - SO THERE WAS NO DANGER OF ELECTRIC SHOCK, JUST
ELEVATED MAGNETIC FIELDS IN THE ORDER OF 150mG (15uT) IN MANY AREAS OF THE
HOUSE AS THE WATER PIPE CAME IN ONE SIDE AND THE ELECTRICITY EARTH THE
OPPOSITE SIDE OF THE BUILDING. AFTER INSTALLING THE NON-CONDUCTIVE PIPE
SECTION THE HOUSE MAGNETIC FIELDS FELL TO 0.5mG (0.05uT). A CLAMP-METER
CAN BE USED AROUND PIPES TO EASILY CHECK WHAT CURRENT IS FLOWING IN THEM.

2/ - WE SHOULD CONSIDER ALL "EMFS" ARE POTENTIALLY SLIGHTLY BIO-ACTIVE.

3/ TERMINOLOGY
WHEN I WAS AT SCHOOL EMF STOOD FOR ELECTRO-MOTIVE-FORCE I.E. A VOLTAGE.
THAT NOW SEEMS TO HAVE BEEN RELUGATED TO "emf".
LANGUAGE CHANGES AND EVOLVES AND NOW "EMF" IS GENERALLY TAKEN TO MEAN ANY
TIME-VARYING ELECTRIC OR MAGNETIC FIELD, WHETHER OR NOT IT IS RADIATING.
IT THEN HAS TO BE REFINED IF NECESSARY BY ADDING:
SLF (UP TO 30 Hz)/ ELF (30 - 300Hz) / VF (voice 300-3kHz)/
VLF (3 - 30 kHz) / LF (30 - 300 kHz) / MF (300k - 3MHz) /
HF (3 - 30 MHz) / VHF (30 - 300 MHz) / UHF (300 MHz - 3 GHz)
SHF (3 - 30 GHz) / EHF (30 - 300 GHz) (the SI designators I am told)
....AND THE SOURCE! The source is important because whereas 50 / 60 Hz
mains fields are "near field" concerns with electric and magnetic fields
being quite separate and not mathematically related, Schumann waves (c 8 to
32 Hz) are actual radiated fields resonating in the Earth/Ionosphere cavity
and do obey Maxwell's radiation equations! Maybe that difference is
important. However even man-made 50 and 60 Hz fields DO radiate from long
transmission lines and have been measured in space at great distances from
the Earth.

So, I think the generic use of "EMF" to mean any time-varying electric or
magnetic fields is now generally accepted as modern parlance. It should not
be used in isolation without describing the source and the frequencies
involved. For example a 200 kHz long-wave radio transmitter of which we
have some very powerful (eg 500kW) ones in the UK has a wavelength of 1500
metres (ie about 1 mile) so anyone within about 200 metres would be almost
exclusively in the near field anyone over about 500 metres in the far field
and those in between these distance - who knows! There ain't any simple
answers and I don't think being pedantic about the accepted meaning of
'EMF' helps our precautionary cause.

I do exclusively use the terms "electric" and "magnetic" fields when
talking to people and in my Reports but EMF is a good generic term that
many of the great unindoctrinated public are just beginning to cotton on to
as maybe something to watch out for and be concerned about. Even the World
Health Organisation EMF Project includes power frequency fields!

Good wishes to all
Alasdair
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Alasdair Philips (aphilips@gn.apc.org)
Director, UK Powerwatch,
EMC Engineer and EMF-bioeffects researcher
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Archive provided courtesy of WaveGuide, http://www.wave-guide.org
Reprinted with permission of Roy Beavers, http://www.feb.se/EMF-L/EMF-L.html
Click to expand...
Is that "our" Karl? Karl Riley?

2112cad.gif


Image property of: www.aymcdonald.com
 
Re: Portable Generators and Ground Rods

I have been away from this thread for 1 day and wow!
iwire Bob
I am not saying I disagree with Bennie, but I need to study that a little more. My post to you about your 3 situations was strictly about those three. As far as the NEC is concerned with those 3 methods, a ground rod is not REQUIRED, but is PERMITTED. Remember we are talking about 'portable' generators in this circumstance.
Bennie's comment about the static buildup is one for concern, if he or someone else could start another thread (it will be easier to follow as this thread has such volume), it would be very interesting to discuss.

One other thing to remember. The NEC has not been written to cover every single situation that exists or can develop in our industry. That is where the AHJ with his/her experience really becomes important. I will add this to the mix. Now that the internet has such a present, an AHJ has valuable resources at his fingertips readily available.

Hickman
Your anger is a sign of passion, that is good, we like people with passion for our industry here. Add to that a little 'humble pie' and I think this forum will become a big asset for you.

Pierre
 
Re: Portable Generators and Ground Rods

Hickman
Your anger is a sign of passion, that is good, we like people with passion for our industry here. Add to that a little 'humble pie' and I think this forum will become a big asset for you.
Click to expand...
As Hickman's anger started right after my post I take full responsibility for raising Hickman's frustration level.

With my self-deprecating reply and my weak attempt at humor, I believe Hickman misunderstood my post and thought my comments were directed at Hickman.

I posted a reply that included an NEC reference [250.30 (A)(2)] to STATIONARY (built-in) generators. Hickman is conversing about a PORTABLE generator. I lost sight of the portable thing and posted a built-in code reference. My bad.

I then tried to cheerfully neutralize my own post. I even asked to have my post deleted. I blew the whistle on my own post.

I believe that Hickman thought I was suggesting that Hickman's post be removed.

I truly am sorry for any confusion caused by my writing style.

THIS THREAD/TOPIC IS ABSOLUTELY FASCINATING AND OF THE UTMOST IMPORTANCE.

My apologies to Hickman for sending things into the ditch.

With remorse,

../Wayne

sorry.gif


[ September 06, 2003, 12:22 PM: Message edited by: awwt ]
 
Re: Portable Generators and Ground Rods

Hickman, I was thinking about your posts and realized that you may be talking about a generator for a house through a transfer switch, in this case the generator does end up being connected to a grounding electrode system, as it should be.


I started this thread about a generator out on its own, no transfer switch, no tie in to a utility.

I think we all agree that we can use a typical 5000 watt generator without any ground rods to power tools etc.

My question had to do with contractors that have large 100KW 250KW etc portable generators to power their equipment.

With no ground rod you could say they are safer, you could touch a "hot" conductor while standing in a puddle and not receive a shock.

Add the ground rod and you get toasted, as now you have a circuit through the earth.

Bob
 
Re: Portable Generators and Ground Rods

Iwire, Aside from the ground rod issues the code needs to take a serious look at the term portable. When I buy a generator from the manufacture I can buy a portable generator. a standby generator or a prime power generator. If you take a prime power generator and slap it on the back of a truck and ground the frame to the bed. Is it really considered portable. If so by who? Or is there other requirements that the manufacture will require.
 
Re: Portable Generators and Ground Rods

hickman,
If you take a prime power generator and slap it on the back of a truck and ground the frame to the bed. Is it really considered portable.
Click to expand...
No, now it is a "vehicle mounted generator" but the rules reamin the same as for a "portable generator" with the exception that the generator frame must be bonded to the vehicle frame.
Don
 
Re: Portable Generators and Ground Rods

Of all the generators that I sell the portables are rated in watts and the standby and prime units are rated in kw. We sell two portable that are 12,500 watts and 15,000 watts and then we have standbys and primes that are rated 12kw and 15 kw. I don't know if this is part if their listing, However I will be visiting the manufacture next month and will ask them about it If anyone else has any questions for them let me know and i will ask.
 
Re: Portable Generators and Ground Rods

It doesn't matter what the generator was sold as.
what will is in how it is used and what it is used for. as the end use will determine what it is classified as. And whether or not it's wired per the NEC requirements as most all generators sold as portable have optional transfer switch's that the manufacture sell to allow these so called portable generators to function as a standby gen-set. so it doesn't matter what it was sold as , As I said before, "The end use will determine what it has to follow in the code.
 
Re: Portable Generators and Ground Rods

Hickman here is a real example of a generator installation that the GC asked me if it was required to have a ground rod.

The Demo contractors bring a trailer mounted diesel generator set and a "Brock" (essentially a small remote controlled backhoe powered by electricity) They have proper receptacles, cord and OCP. The Brock takes 60-100 amps 480 volt 3 phase.

What code article could I give the GC that shows this generator is required to have a ground rod.

I say none, it does not require a ground rod, I can only think of two reasons for this.

1)The code making panel was not aware of portable or vehicle mounted generators of this size.

I find this highly unlikely, the CMPs are not made up with fry cooks, they are made up with knowledgeable people.

2)The ground rod serves no purpose in an installation like this.

I find this more likely, other than the we have always done it that way response, which I have to put aside too.

Can you think of a reason that a ground rod is needed?

What will driving a ground rod do to improve the safety of this installation?

Bennie mentioned a static charge but I see ungrounded generators all the time with no one getting whacked, perhaps this would be a problem if the generator was truly isolated from the earth but most times some part of the generator is touching the earth.

Would this contact with the earth keep the static charge from developing?

Although it has been mentioned, no one is offering any reference material to back up claims of objects like cars and generators holding a charge like a capacitor after a lightning strike.

Yes, I know code is minimum and I am always allowed to add a ground rod.

So what would a ground rod do for us in this installation?

Bob

[ September 08, 2003, 05:30 AM: Message edited by: iwire ]
 
Re: Portable Generators and Ground Rods

Originally posted by hickman:Charlie why do you think that no current will flow if the neutral is cut before the service disconnect?
Click to expand...
Look again. What I said was that no current would flow into planet Earth.

Current will flow from a breaker on (let us say) the left side of the panel, along a ?hot wire? to a receptacle, into a toaster, along the ?cold wire? (i.e., grounded conductor) back to the panel, and into the neutral bus of the panel. From that point, since there is no connection back to the neutral point of the service (it having been accidentally cut), current will flow along another ?cold wire? to a different receptacle, into a vacuum cleaner, out the ?hot wire? back to the panel, and into a breaker on (let us say) the right side of the panel. The result is that the two appliances have 240 volts across them. If they have the same internal resistance, they will share the 240 volts equally, and not be the wiser. If one has a higher resistance than the other, both will be destroyed.

I reiterate, until you alter the accident by including a connection between a ?hot wire? and (for example) an external metal case, then planet Earth does not enter into the current paths, and the ground rod plays no role.
 
Re: Portable Generators and Ground Rods

I buy that, However what if the loads of the panel are not balanced well.
 
Re: Portable Generators and Ground Rods

Originally posted by hickman:
I buy that, However what if the loads of the panel are not balanced well.
Click to expand...
Still has nothing to do with a earth reference. The imbalance is carried on the grounded conductor, not earth.
 
Re: Portable Generators and Ground Rods

Let's look at one more Ground Rod Graphic from Mike Holt.

1016666286_2.gif


Roger
 
Re: Portable Generators and Ground Rods

Dear Dear Hickman
I just don't know what we could say to get you to understand that a ground rod does not play any part in safety at voltages below 600 volts. It just don't!

After 112 post of it being explained in every concept and with every possibility you seem to not be able to grasp the knowledge given here.

All I can say is if you have a printer print out these 8 pages of knowledge and study it, have a friend who maybe can explain it in person to you.

But after all this I don't think you will let go of "This is the way I always done it" attitude and as long as you hang onto this you will never be able to grow and learn anything new. I said this before a closed mined is a mined that has stopped learning.

All I can say is Keep selling those generators. But I would leave the advice to those who understand what it's all about.


P.S. Count it as constructive criticism's
If it wasn't for this I would probley be right where you are as I to was stubborn and would not give up that I didn't know it all. so just let go and open your eyes.
Wayne
 
Re: Portable Generators and Ground Rods

Thank you for opening my eyes with these eight pages. Really helpful stuff. It also shows that even though grounding is priority #1 with inspectors, most of us don't really understand its purpose.

[Note to Hurk27: Now that you signed your post Wayne, and since you were here first, I will start signing mine as
Wayne C.]

../Wayne C.

PS: Have you ever noticed how many mass murderers have the middle name Wayne? I'm proud of my name. I like my name. I'm glad it's not my middle name :p
 
Re: Portable Generators and Ground Rods

Lets quit picking on Mr. Hickman. It appears he is a salesman and does not have a electrical background. The manufactures (lawyers) are printing gibberish in their instructions to cover you know what. We electrical professionals are the ones who are ultimately responsible for the installation if involved. FYI Mr. Hickman, a ground can kill!
 
Re: Portable Generators and Ground Rods

I assumed Hickman was the Hickman on the NEC code panel-- from the IBEW.

../Wayne C.
 
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