Re: ADT DEALER - A shining example for work safety.

[Effenpig1 <dirtyspicevent@xxxxxxxxxxx>]

On Dec 19, 1:39=A0pm, JoeRaisin <joeraisin2...@xxxxxxxxx> wrote:
> Effenpig1 wrote:
> > On Dec 19, 10:33 am, JoeRaisin <joeraisin2...@xxxxxxxxx> wrote:
> >> Spellcheck Patrol wrote:
> >>> On Dec 16, 12:08 am, "John Smith" <aliasJowB...@xxxxxxxxxxxxx> wrote:
> >>>>http://yfrog.com/1aadtsafteyexamplej
> >>>> Yep. =A0Both sides same thing. =A0Aluminum ladders. =A0 <
> >>> That's an authorized dealer logo on the vehicle
> >> Think I could get one of those?
>
> >> Seriously though, since we are talking about aluminum ladders, and mor=
e
> >> to the point - the reason for not using them, ie: electricity; I have =
a
> >> a question about something that came up on an oil field consulting job=
 I
> >> was just on (trust me, if you were as ADD as I am this logic would mak=
e
> >> perfect sense).
>
> >> I'm no electrician (and I can't afford to stay at a Holiday Inn Expres=
s)
> >> and don't generally like to play around with big-boy voltages but if I=
'm
> >> not mistaken, ground is ground the world around...
>
> >> Many many years ago is used to work as a mud logger
> >> (http://en.wikipedia.org/wiki/Mudlogger) and am re-training so I can
> >> pick up some cash here and there. =A0It's good money but the jobs are
> >> infrequent at best.
>
> >> Anyway - I'm working out of the company man's trailer and, yesterday,
> >> after he takes off his thick rubber boots and steps out he finds that
> >> the trailer skin is electrically hot.
>
> >> Long story short we finally found that the coffee pot had a short
> >> somewhere that was feeding 110 back into the ground circuit. =A0Trust =
me,
> >> the loss of the coffee pot was a bigger blow than finding the 110 on t=
he
> >> door handle.
>
> >> Oil rig electrical systems are notorious - partly due to rickety
> >> generators (that put out 90 VAC one minute and 200 VAC the next) and
> >> partly due to roughnecks.
>
> >> Roughnecks, God bless 'em, are some of the toughest, hardest working
> >> folks I've ever met and absolute geniouses at making just about anythi=
ng
> >> "work" via bubble gum and band-aids but, as creative as they are, if
> >> pressed to do thing the "proper way" they would be clueless.
> >> Surprisingly enough - these fixes almost never raise the eyebrows of
> >> OSHA inspectors despite how scary it looks.
>
> >> As a result, some of the folks who bring work trailers to the location=
s
> >> will put out their own ground stakes as an added precaution. =A0The
> >> company man has taken (what he considers to be) the added measure of
> >> removing the ground from the incoming power cord so he has only one
> >> ground on his systems.
>
> >> His trailer is about 100ft from the rig on frozen, sandy ground and I
> >> suspect the poor ground reference back to the main panel is why we
> >> didn't trip the breaker in the generator house when the short occurred=
.
>
> >> Does anyone know if having both grounds present is a problem? =A0I can=
't
> >> remember what the rules (or more important - the why's) about proximit=
y
> >> regarding two ground stakes in in an electrical system.
>
> >> He swears by the separate ground stake for the trailer so that's not
> >> going away, but I think I should try and talk him into reconnecting th=
e
> >> rig ground as well.
>
> >> He's a reasonable guy and if it's the right thing to do he'll go along=
.
> >> =A0 I just want to be sure it's the right thing.
>
> >> Also - the trailer's real sensitive equipment (gas monitors and such)
> >> are protected by redundant UPS's and a rheostat.
>
> >> Any help? =A0I got to go back out tonight or tomorrow..
>
> > Obviously code varies, but:
>
> > Yes, ground is ground the world around, but quality of ground is not
> > the same the world around. Different types of ground conditions can
> > play a role. I knew of guys who tested ground rods by trying to trip a
> > 15 amp breaker by shorting it to the ground rod. While not the proper
> > way to do things it does illustrate a point. It is likely the
> > resistance between these "additional" trailer grounds and the
> > generator grounds is too high, so they are not equal to a ground
> > supplied at the generator. It's likely if you were to touch a live
> > wire from the generator to one of these "additional ground rods it
> > would spark but not trip the breaker. They are likely causing the
> > problem by removing the grounding conductor and supplying their own
> > ground. Though the grounding at the generator may be insufficient too.
>
> > Everything conductive on the trailer should be bonded back to the
> > ground bus. Also the neutral should be separated from the ground and
> > any appliances or equipment with bonding straps between the ground and
> > neutral should have them removed.
>
> > The trailer itself should get ground from the supply cord, it
> > shouldn't be grounded itself. I would suspect poor grounding at the
> > power generating station or undersized grounding conductor.
>
> That's the thing - he has disconnected the ground from the generator and
> is grounding the trailer independently.
>
> So you are saying he should lose the trailer ground and reconnect the
> generator ground. =A0What if, rather than connecting the ground stake to
> the ground bus - he connects it to the trailer frame?
>
> Gas & oil rigs attract lightening during those rare occasions that
> conditions are right, and structures around them get a lot of big surges.

Trailers are supposed to have all non-electrical metal already bonded
to the ground bus, frame, siding, everything, and its all tested
before it leaves the factory. That is assuming these are trailers made
in North America and not Botswana or something. You should already
have continuity from the frame to the ground bus. As far as lightning,
any lightning arrest system should be independent of the trailers
ground system.

Even in parks where there are sub-panels right at the trailer the
ground comes from the main distribution panel, there would not be
another ground rod at the sub-panel.

I would still suspect the grounding back at the generator. In poor
soil conditions it can take several 10 foot copper ground rods to do
what 1- 8' galvanized rod would do in good soil.