Author Topic: Just a question on wiring  (Read 1233 times)

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Seedler

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Just a question on wiring
« on: August 17, 2006, 02:45:27 PM »
Hi,  I just wanted to ask a small question.  I have seen plans that have the negative of the battery bank connected to an earth spike, or eirth wire.  Why is this done?  Is it for safety reasons against lightning?  I have had my system up and running for a few years now and do not have my negative grounded.


I just thought I might be doing something wrong.


Dee.

« Last Edit: August 17, 2006, 02:45:27 PM by (unknown) »

Vtbsr

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Re: Just a question on wiring
« Reply #1 on: August 17, 2006, 12:28:22 PM »
This is for safety. Do you have your 115v outlets grounded? I have heard that the battery bank can help suppress voltage spikes. There is a  chapter in the electrical code on low voltage wiring(48v or less).
« Last Edit: August 17, 2006, 12:28:22 PM by Vtbsr »

stephent

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Re: Just a question on wiring
« Reply #2 on: August 18, 2006, 11:27:19 PM »
If you are going to ground a wind generator wiring against lightening --I would do it before the battery bank. That's after an electronic device or 2 and a little late...

Not so sure how a lightening bolt imposed across a grounded battery would appear to the lightening bolt, but I figure the battery wouldn't fare well.

Might try wrapping the wires/cables (insulated) from the genny around a ground rod a couple times--lightening doesn't like to turn sharp corners, take it away from the rod at 90 degs. (at least it might confuse it and make it dizzy)

Grounding a battery bank less then 50 volts is not required by US code (unless local code prevails).

Grounding any PV system on a rooftop IS required (common metal parts--again US code), but not necessarily any of the wires coming from the bank, depending on total volts available. (so is the GFCI part!!)

Inverter/controller cases (metal part) do have to be tied to a ground.

The metal towers supporting the wind generator do have to be grounded.

Some say grounding invites lightening--some say it helps keep the after effects down.

I've seen lightening run across my 80 meter ham antenna and never even come into the ham shack or even affect the radio which was attached...And then seen whole towers with split legs and ruined antennas and just about the whole electronics ruined inside the 'radio room".....

The grounding usually mentioned is for more safety purposes--except for the tower/support grounding rules.

Never could understand the reasoning behind making any of the wires "hot" to ground--outside of the reason that it keeps a bit more crap (maybe) from running into your house from off the grid---seems more sensable to me to have both of the normal wires (hot or neutral or DC +-) being able to be kissed (one at a time of course) and never get a shock while standing barefooted in salt water.

I do electrical construction work, and teach it also (electrical/electronic theory), and never have understood why I should be able to be killed by just touching just ONE wire if I am grounded (I wear 4000 volt tested (when new)  electrician work boots while working--I'm an OLD paranoid electrician and plan to live a while longer!)
« Last Edit: August 18, 2006, 11:27:19 PM by stephent »

Clifford

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Re: Just a question on wiring
« Reply #3 on: August 20, 2006, 10:26:37 AM »
For 12/24V (and probably 48V), I would be a true believer of running it ungrounded.


Like in the previous comment, I don't like the idea of having either pole grounded, and thus touching a single wire could raise one's hair.


However, I am also convinced that it is essentially impossible to get a significant shock ad 12/24V (but, one can still make spectacular sparks).


However, a point in the code....


If you run an ungrounded system, then you are supposed to run all switches (and breakers/fuses) as two pole.  Thus, in a sense, you have twice as much work getting it all wired up.


In theory, grounding a single pole is supposed to act as a sink against voltage spikes.  I'm not convinced this is true, especially when running a small 110/220V system where one can easily overload a single phase.  You will find that cheap (auto type) inverters often have problems with a grounded pole.

« Last Edit: August 20, 2006, 10:26:37 AM by Clifford »