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Bob you are sooooo right about the three wires. I already have 160 cords ready to go for my new boxes and every one of them are 2 wire except for the two power leads.

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blearning wrote:


when you are using GFIs (Ground fault interrupters), that ground becomes a very extremely, highly, critically, important (notice the fixation) part of the safety factor.

I agree that grounds are important and should not be mixed up or confused with neutrals. However, I believe a GFCI will work and be effective without a ground connection. A GFIC senses a difference in current between the hot and neutral conductors. If this difference is 5 mA or greater (or what ever the setpoint of the GFCI) is it will trip. This is why it works for ungrounded Xmas lights and such. It trips when part of the "hot" line current flows thru an Earth ground (or maybe a person then Earth ground). This means the hot current is greater than the neutral current and the imbalance trips the GFCI.

I suspect most of the loads connected to the controllers are ungrounded. I wouldn't bee suprised to see a day when metal wire frames had to have a ground to be considered a UL listed device.

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When working with Electricity SAFETY FIRST. My concern is Should the Green wire Be attached YES, YES YES, it should be attached in a manner so that it can go back to the fuse box uninterrupted, meaning there are no devises that will break this connection.

Please when it come to electricity TAKE NO SHORT CUTS (no pun intended) it may not only save your life but also someone else's.

This information was taken from the web site "Increase Electrical Safety With Ground Fault Circuit Interrupters"
http://www.naturalhandyman.com/iip/infelectrical/infgfi.shtm

Does a GFI need to be grounded to work properly? I want to put one in my bathroom, but my outlet is an old, ungrounded type.

According to the NEC, it is allowable to install GFI's in ungrounded situations. This makes sense, since the GFI is not dependent of the ground to function. Remember, it does not measure shorts to the ground, it measures the current difference between the hot and neutral wires. A sudden difference, indicating that there is another path for the electricity to flow through... you, for example, causes the GFI to open the circuit and save you from permanently curly hair.

Of course, most safety-conscious electricians prefer not to install a grounded-type "three prong" outlet in an ungrounded situation. Think about it... once the outlet is installed, there is no way for anyone to know if the outlet is really grounded or not without testing it. Thus, there is a hidden shock hazard should an appliance or tool that needs grounding... has three-prong plug... is plugged into this outlet.

However, the NEC allows GFI's to be installed in ungrounded situations PROVIDED THAT the outlet is labelled "ungrounded". Though not "officially" approved in the NEC, the grounding hole in the GFI can be permanently defeated by using an epoxy or other adhesive to seal the hole.

Though a GFI will activate if a grounded appliance develops an electrical short circuit to ground... such as when YOU touch a metal saw and become the path to ground... you will experience a momentary electrical shock. This could be a minor tingle or could be more catastrophic, especially if you are on a ladder or roof. This excerpt is from an OSHA (Occupational Safety and Health Administration) article on wiring in nursing homes and the dangers to employees working with ungrounded outlets...

"The ground-fault circuit interrupter, on the other hand, is a fast-acting device which senses small current leakage to ground and, in a fraction of a second, shuts off the electricity and interrupts its faulty flow to ground. The rapid response of the GFCI is fast enough to prevent electrocution and this protection is independent of the condition of the grounding conductor.

A GFCI can prevent an electrocution; however, it cannot by itself prevent an initial electric shock to an employee before it interrupts the circuit. This initial shock could lead to injuries of an indirect or secondary nature in which involuntary muscular reaction could cause bruises, bone fractures, and even death resulting from collisions or falls. Therefore, GFCIs are in addition to, and not in lieu of, equipment grounding conductor requirements."

(Here is a link to the complete article:

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=FEDERAL_REGISTER&p_id=13346 )

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Bob_Moody wrote:


but make sure if you drive a copper rod for earth ground that you only tie ground(s) to it.

Do not tie (bond) neutral back to it as you will lift the path and change the potential of the current flow in relation to the bonded ground at the main breaker panel. This may seem a silly reply, but the question has come up several times in the old forum.

It's not silly; you haven't seen my big aluminum box or the big relay.

I'm OK. The neutrals are isolated from earth in my control box. In fact each neutral is isolated from the other neutrals (five 110v. feeds will go to this box). They (the neutrals) are only bonded at the breaker box. I'm quite the stickler for using single point return lines.

See the "New for '06" link in sig. for a look at the 30x36 nema 4 aluminum box I plan to use for the coming season.

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blearning wrote:

[sNIP]
when you are using GFIs (Ground fault interrupters), that ground becomes a very extremely, highly, critically, important (notice the fixation) part of the safety factor.
[sNIP].

I am not a GFIC expert but I thought that due to the way that they work that the ground becomes less important when GFICs are in use. The way I understand it (at a very high level ) is that the GFIC does not use the Ground wire at all. What it does is measure the current on the Hot and Neutral and if they do not match there is a leak and they shut off the power.

I know that in some circumstances that by code, GFIC can be used as a substitue for a third wire (ground) in a circuit.

The only reason that I bring this up is that I want to make sure that folks understand that having metal enclosures grounded is more important with you DO NOT have a GFIC than is is when you do. BUT MOST IMPORTANT, IF YOU HAVE A METAL ENCLOSURE IT SHOULD BE GROUNDED!!!!

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RR,

So is there a traffic light in Missouri somewhere missing its controller box ?? :laughing::laughing:

Seriously, thats a GREAT looking box. If you don't mind could you point me to where I can get one? I imagine they cost as much as a 426 Hemi.. but WOW . what an enclosure.



-- Bob

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Bob_Moody wrote:

RR,

So is there a traffic light in Missouri somewhere missing its controller box ?? :laughing::laughing:

I imagine they cost as much as a 426 Hemi.. but WOW . what an enclosure.



We use these to house roadside weather stations. This one came in with a busted padlock bracket and broken mount. The insurance paid and they didn't want it back. I asked for it and eventually got it.:)

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Can't beat being in the right place at the right time. That is one heck of an enclosure.

I'd really like to see the completed project when you get it built.

-- Bob

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Bob, I retrieved the 4 pole 30A relay tonight from the rafters where it used to turn on the display. It now sits next to that monster 3 pole 50A relay so 7 115v. inputs can be simultaneously powered by one digital lamp timer. This is in preperation for turning those white papers into actual LOR units that should arrive some time in April or May. To start, there will only be 3 @ 20A and 2 @ 15A. An 8th 115v. feed goes to the porch light and is always on to run the timers and relay coils.

When the new units are installed and all those brown & white wires are attached to them, I'll take a new updated picture of the box. It should have a finished look at that point.

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