Boat dock electrical current in water

[jb3551]

I often get called to test boat dock electrical systems which includes the shore side disconnect and the switches and receptacles on the dock. As well as making sure GFCI's are working properly and check for grounding and bonding. I also measure for current in the water. As I listen to one of your videos dealing with the AEMC model 565 for measuring current in water using milliamps I have a question.

Previously I have been checking for electrical current around boat docks by using a regular multimeter and by dropping the negative lead into the water and checking the ground in the receptacle. I would pick up 0.2 amps or a little more at times. But you had mentioned about measuring in milliamps. With the AEMC 565 you recommended, what's the process for using that meter in measuring milliamps? That's one thing you never discussed in your video was how to measure electrical current in water.

 

[zbang]

Please understand that while many quite knowledgeable people read this forum, Mike himself does not. (I'm sure someone else will answer your questions.)

 

[Little Bill]

I often get called to test boat dock electrical systems which includes the shore side disconnect and the switches and receptacles on the dock. As well as making sure GFCI's are working properly and check for grounding and bonding. I also measure for current in the water. As I listen to one of your videos dealing with the AEMC model 565 for measuring current in water using milliamps I have a question.

Previously I have been checking for electrical current around boat docks by using a regular multimeter and by dropping the negative lead into the water and checking the ground in the receptacle. I would pick up 0.2 amps or a little more at times. But you had mentioned about measuring in milliamps. With the AEMC 565 you recommended, what's the process for using that meter in measuring milliamps? That's one thing you never discussed in your video was how to measure electrical current in water.

I would suggest you contact Mike. You can reach him at mike@mikeholt.com

 

[Another C10]

I know on one service call I had a voltage reading of 97 volts by simply putting 1 lead of a digital meter in the water of a pool and the other to a corded neutral.

The problem I figure was from a break in the insulation allowing the voltage to bleed off into the surrounding concrete decking, no GFI protection.
This condition occurred with or without the light on. Problem was resolved with zero voltage once I replaced the underground wiring.

 

[winnie]

Have you looked at the AEMC 565 manual? It is a sensitive clamp on ammeter, so you use it by clamping around conductors of interest to measure current flow.

For example you could clamp around an EGC or bonding cable going to a dock to measure current flowing on this 'ground', or you could clamp around all of the conductors for a circuit to measure 'residual current' (the current leaking out of that circuit).

I do not know the specific methods that Mike was describing in the video. But perhaps the info above combined with your watching the video is enough for you to figure things out.

Jon

 

[Fred B]

Current in water near a marina or private dock is an big issue. Stray voltage in water can come from many sources including the POCO. Thus the newest code has requirements for signage for "No Swimming" near or around a dock even on residential docks now. Also the reason the code has been over several cycle been reducing the maximum trip level of the dock/shore power GFCI protection.

OP A typical GFCI for personal protection is 5 miliamps or 0.005 amps. Your reading of 0.2 amps would be the equivalent of 200 miliamps. A GFCI protection for shore power is (2017 NEC) 30 miliamps or a reading on the meter of 0.030 amps. Most amp meters don't read down to that level thus the suggestion on the video for that particular meter that reads to that miliamps level, any meter that can be gotten that will read down to that level is suitable for marina inspection purposes. On the model referenced there is a seperate setting on the meter to get miliamps, also the readings capable is all the way down to 0.01 miliamps or 0.00001 amps (according to mfg). As opposed to most meters only to 0.01 amps. Hook up and reading of meter is same as any other clamping amp meter, there is information in the user manual on different setup configurations depending on what you are trying to read.