AC Grounding

[CharlieJ]

Chala/GordMay
When working on supposedly "tagged and locked" circuits, something that you can never be sure of on any pleasure vessel, I keep my Fluke (or equivalent) contact voltage tester Fluke 1AC-II / 1LAC-II VoltAlert in front of me and use it to test the conductor or component that is "dead" before I touch it. This action occurs after I have initially tested the conductor or component with a Fluke electronic "Wiggins" Fluke T+PRO / T+ Voltage and Continuity Testers.

This old electrician intends to get quite a bit older.

Chala-
I would appreciate a response to the remainder of the comments in my 7/24/09 post.


Regards,
Charlie

[unbusted67]

Originally Posted by donradcliffe

2. Press at least the freshwater marinas to install RCD devices, which would have prevented many of the electrocution deaths regardless of how the AC and DC grounds were wired. The RCD would force the boatowners to solve their wiring problems if they wanted dockpower.

What is RCD?

[GordMay]

RCD = Residual Current Device
An RCD provides much the same functionality as the GFCI (ground fault circuit interrupter), protecting against an imbalance of current on the hot and neutral wires. If the current is not equal on both wires, some current is being lost to ground (a ground fault), and the unit trips (opens) cct).

Originally Posted by CharlieJ

Chala/GordMay
When working on supposedly "tagged and locked" circuits, something that you can never be sure of on any pleasure vessel, I keep my Fluke (or equivalent) contact voltage tester Fluke 1AC-II / 1LAC-II VoltAlert in front of me and use it to test the conductor or component that is "dead" before I touch it. This action occurs after I have initially tested the conductor or component with a Fluke electronic "Wiggins" Fluke T+PRO / T+ Voltage and Continuity Testers...

Indeed; just the sort of belt & suspenders approach to electrical safety I advocated.
In addition to the performing the various & multiple "tests", it can't hurt to ground out any conductor, prior to tentatively touching it.

FWIW: Those non-contact voltage testers (Cct. Alert, middle left) are great tools, but should only be trusted to indicate that a circuit is “live” - not that it’s safely “dead”.

[s/v Jedi]

I have my license for building electrical systems too and can support Gord here that after all the tests like Charlie described, we still brush the wire with the back-side of a finger before grabbing them. The tester is not trusted with out live, that's all.

Still, nobody seems to realize that most boats have NO grounding system so there's nothing to connect the safety ground from the shore power to. For those boats it's stupid to connect it to the battery negative as that is NOT a grounding system. Best thing is to install dynaplate(s) making a ground system and putting an isolation transformer in but the other way is outlets with GFCI or those RCD thingies. (what's the difference between an RCD and FGCI outlet??)

cheers,
Nick.

[CharlieJ]

Nick-In the USA, the GFCI outlet has a trip spec of 6 mA. The whole boat RCDs that have been discussed in this thread have a 100 mA/100 msec trip spec.

Regarding "brushing the back of the hand against a conductor..." my strong position was based on the WIDE range of expertise amongst the readers of this forum.

Best regards,
Charlie

[goboatingnow]

The whole boat RCDs that have been discussed in this thread have a 100 mA/100 msec trip spec.

I dont think so, The ABYC ELCI is a 30ma leakage spec.

[gs41escapade]

Originally Posted by CharlieJ

Chala/GordMay
When working on supposedly "tagged and locked" circuits, something that you can never be sure of on any pleasure vessel, I keep my Fluke (or equivalent) contact voltage tester Fluke 1AC-II / 1LAC-II VoltAlert in front of me and use it to test the conductor or component that is "dead" before I touch it. This action occurs after I have initially tested the conductor or component with a Fluke electronic "Wiggins" Fluke T+PRO / T+ Voltage and Continuity Testers.

I can't tell you how many times a supposedly OFF house circuit turned out to really be on a 3-way switch that the homeowner 'remembered' after my voltmeter check.

[chala]

CharlieJ
When working on an engine which is AC earthed how do yo “tag and lock” an earth wire? And what happen if it becomes temporary live?

[gs41escapade]

Originally Posted by s/v Jedi

I have my license for building electrical systems too and can support Gord here that after all the tests like Charlie described, we still brush the wire with the back-side of a finger before grabbing them. The tester is not trusted with out live, that's all.

I must confess, I do the backside brush test even after the fluke tests. Habit. And saved me from potentially worse interactions with wires more than once.

[CharlieJ]

goboatingnow-You are absolutely correct...the ABYC standard is 30 mA/100 msec as I posted in this thread earlier. Fingers moving faster than brain!

For those that have good results with the brush test...excellent. I still think that there is such a wide level expertise on this forum that I would not recommend this.

Charlie