Re: EOL's

["Russell Brill" <russwbrill@xxxxxxxxxxxxx>]

"Nick Markowitz" <nick-markowitz@xxxxxxxxxxx> wrote in message
news:ud9Kf.951$F94.878@xxxxxxxxxxx
> Looks like Robert is up to his old stunts again so here is my 2 cents
> worth
> with 25+ years of residential and commercail  low voltage alarm and high
> voltage 120 to 480 volts 3 phase work with resistors.Plus working as a
> broadcast engineer at a 5000watt AM station.
>
> I have seen the 2.2 k resistors on FBII equiptment go low
> around 1500 ohms on 12 different  ocasions due to power surges and
> enviromental conditions  and I have seen circuits with end line resistors
> get tricked in metal buildings when the positive makes ground even with
> the
> resistor in proper place the door was able to be opened and no reaction
> from
> the panel.  Saw this happen with the old class A type loops with Holmes
> Direct Wire equiptment which is why we never put the switches in the
> posistive loop and in the olden days we ran the ground side of the alarm
> circuit loop thru a copper water pipe in a building  to detect  circuit
> tampering. or accidental circuit grounds.which was a requirement for UL
> burg
> systems back then.
> As far as resistors going high have only seen this 3 times and again
> enviromental problems caused it when the resistors material deteriorated.
> All electronic components eventually dry up and go bad thats why they say
> 10
> years on most items made these days.Yes I have a 45 + year old radios down
> stairs which still fire on but they are the exception not the rule.
> The resistors made today are much higher quality than old days but they
> can
> and do drift under the right conditions.
> even the 5% tollarance ones.
>
>
It's my understanding that in certain parts of the country Lightning can be
a problem, the voltage and current that a nearby strike causes on the
protection loop blows the resistors...... Its been known to weld contacts
closed also......