about grounds… a New Discussion

Sat Oct 12 13:36:04 EDT 2013

WOW !! Guys, it looks like grounding hasn't changed much yet has. Dave 
is stating what I knew years ago about bonding neutral and ground 
together at a panel. I even recall one job (for a utility company) that 
required bonding at sub panels. The place was a 24 hour/seven day 
operation that didn't allow for a shutdown so that in place of a 
grounding locknut (it was piped,wired and energized) I ended up using a 
grounding wedge which was nothing more than an open ended washer (with 
grounding lug) that slipped in between the pipe locknut, insulated 
bushing and panel can. It was the only time in well over 30 years that I 
knew about or used a grounding wedge. You can learn something new every 
day. This morning I was talking with one of my electrical engineer 
cousins about this grounding subject and he interjected about how 
frequency can play a part in voltage drop. I was amazed because although 
I discussed it here he and I had never talked about it.
I think the earlier comments about a compromised neutral/ground/common 
can wreak havoc with balance of voltage between the two legs of a single 
phase of 230 VAC was specifically valuable as a trouble shooting 
condition and pretty basic to operating today's electronic equipment. It 
is very possible that what might be seen as a software issue is just a 
basic electrical one. When you read how these X10 devices work you can 
appreciate how stable your AC needs to be. Sending signal pulses through 
60 cycle current(on a 433MHZ carrier) when it is at zero state is pretty 
neat stuff to me. The guy who conceived this process back in 1980 was 
genius (imho) and really thinking out of the box.

Warren

On 10/12/2013 12:10 PM, Dave Hobson wrote:
> I'll admit that I haven't followed this entire discussion but the 
> ground and neutral should be bonded together at the main power panel. 
> The subpanel is definitely grounded and all the circuits that follow 
> the only thing is that the ground and neutral should not be bonded 
> together at the subpanel as they are at the main panel.
>
> LTRS, LLC
> dave at ltrs.com <mailto:dave at ltrs.com>
> 651-643-0643
>
> On Oct 12, 2013, at 10:49 AM, George Handley <ghandley at kc.rr.com 
> <mailto:ghandley at kc.rr.com>> wrote:
>
>> Good morning Ned,
>>
>> Needless to say, your response to my subject line caught my attention 
>> this AM because it says something that smacks of another grounding 
>> inconsistency.
>>
>> Specifically, you stated: "The basic approach is that grounds should 
>> be strapped to neutrals
>> at main panels but not at sub panels,"
>>
>> I've never claimed to be any electrical engineer, but this statement 
>> smacks of absurdity to me.
>>
>> However, you may also be aware that I have been deeply involved with 
>> X10 grounding needs *this week,* and I have to say that between my 
>> KCP&L lineman who found my entire ground wire disconnected (Not to 
>> mention loose wires everyplace) in the utility pedestal, to several 
>> on this list, and now even one of my electricians who are 
>> quite emphatic when they say that from their experience, or known to 
>> them from their own locations, _the utility company often times does 
>> not hook up the ground wire_ coming from a home's service panel to 
>> their equipment.
>>
>> Many other highly experienced folks here congratulate me for FINALLY, 
>> after four years, uncovering the largest most grievous error for why 
>> I've experienced X10 funnies. I do understand that certain 
>> municipalities and/or building codes have conflicting rules, but on 
>> this subject, I protest.
>>
>> I suspect you and I will start a very educational debate amongst the 
>> List members on this subject, because there seem to be diametrically 
>> opposed views here on what I would have assumed to be a straight 
>> forward subject.
>>
>> Now whatever I have to say regarding my self taught knowledge of PLC 
>> (X10) is expected to agitate a few here, but certainly needs 
>> clarification to the group, because both groups can't be correct.
>>
>> From everything I've ever read about how X10 works, and the litany of 
>> things that will stop it from working consistently, and particularly 
>> with some of the expensive Leviton switches and filters, X10 *has to 
>> have a separate ground to work*… just as important as both the load 
>> and common wires. Many of the parts installation instructions make 
>> this point in *bold*!
>>
>> While it's obviously true that evidently some here do not have their 
>> separate ground wires immaculately installed and maintained, others 
>> claim it is of supreme value. I have two main sets of experiences to 
>> routinely discredit this idea that you can ignore the X10 device's 
>> ground wire connection, which, incidentally in our home terminates in 
>> a main and sub panel that are most definitely grounded together.
>>
>> I maintain that if the X10 device has a separate ground wire… you'd 
>> better use it, or expect it either not to work at all or work 
>> inconsistently. Also, yet to be explained, or proven, or tested yet 
>> after our utility repaired our service, is the fact that a properly 
>> installed Leviton whole house surge protector, at least  prior to 
>> last Thursday, will consistently cause many of my X10 circuits to 
>> cease working.
>>
>> Ironically, after installing this Leviton unit, and finding that I 
>> had the same X10 funnies going on identical to the other much more 
>> expensive Eaton whole house surge protector, I disconnected the two 
>> load wires to get back to some stability. But guess what? The 
>> problems remained. Next I disconnected the common wire too, but the 
>> problems STILL persisted.
>>
>> It wasn't until I disconnected the ground wire to this unit, that 
>> sanity returned. So, I believe I know, first hand, that the grounding 
>> wire and X10 do have a meaningful electrical purpose.
>>
>> I'll stop here, and await the storm of retorts. :-)
>>
>> Thanks,
>>
>> George
>>
>>
>>
>>
>> On Oct 12, 2013, at 9:09 AM, ned+xtension at mrochek.com 
>> <mailto:ned+xtension at mrochek.com> wrote:
>>
>>> On the subject of GFCIs, it is a common misconception that GFCIs 
>>> depend on
>>> having a proper ground reference.
>>>
>>> This is not the case. GFCIs operate not by checking for a flow of 
>>> current to
>>> the ground, but rather by comparing the flow of current on one 
>>> conductor (hot)
>>> to the other (neutral). If these aren't equal thSuch a flow is not 
>>>  returning
>>> by another path and the device trips. Note that this is not 
>>> necessarily a fault
>>> to ground - it could be a fault to a different neutral connection - 
>>> and so the
>>> term "ground fault" is something of a misnomer. The better term for such
>>> devices is "residual-current circuit breaker".
>>>
>>> The circuit is actually very simple: Both conductors are run through 
>>> a sensing
>>> coil, forming a differential current transformer. If the current in both
>>> conductors are equal they cancel each other out, if not they induce 
>>> a current
>>> in the coil. The rest of the circuit detects this current and trips 
>>> the breaker
>>> if it exceeds some threshhold.
>>>
>>> Note that a common application of GFCIs is as a way to upgrade to 3 wire
>>> outlets without having to upgrade the in-wall wiring. It is 
>>> perfectly legal to
>>> install a GFCI in a box without a ground wire because the GFCI 
>>> doesn't need it
>>> to operate correctly. Such outlets are supposed to be labeled as not 
>>> providing
>>> a true ground, although in practice I rarely if ever see such 
>>> labeling done.
>>>
>>> As for panel grounds, the rules about those are primarily intended 
>>> to prevent
>>> ground loops since having current always flowing on ground wires is 
>>> something
>>> of a no-no. The basic approach is that grounds should be strapped to 
>>> neutrals
>>> at main panels but not at subpanels, but see the NEC for specifics, 
>>> and note
>>> that there can be state, county, or even local requirements that 
>>> amend the
>>> NEC.
>>>
>>> Ned
>>> _______________________________________________
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>>
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