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Old 03-03-2013, 11:37 AM   #1
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AC/DC Clamp on ammeter

While trying to untangle the battery wiring on our new boat I decided a clamp on DC ammeter would be a great help. Found one at Sears and it is one of the best tool purchases I ever made. It measures DC current and also gives the direction of current flow. By checking the current at one of a cable and then doing the measurement at what may or may not be the other end you can easily determine if the cable is the same.

The unit does not just do current measurements but also measures frequency so you can check the genset to see if it is really outputting 60Hz. Of course it also measures AC/DC voltage, resistance, capacitance and has a temperature probe.

Price was about $60-70.

Just for clarification, I have no connection with Sears, just that I have found this to be a really useful tool.

Bob
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Old 03-03-2013, 12:51 PM   #2
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Having one off these tools is definitely a great trouble shooting addition.

BUT....I got a clamp on from Sears about 3 years ago and it barely lasted a year with light use...internal something as I had to squeeze it to get all the LED display to work..a rubberband made it last another year...finally gave up and got a much nicer one at Home Depot for around $130 (but less with my discount)
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Old 03-03-2013, 01:46 PM   #3
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I also keep an inexpensive voltmeter plugged in to an outlet at all times. Many marinas have low voltage that can damage some sensitive equipment.

AC Voltage Meter - Intersource Enterprises D10-170 - Voltage Monitors - Camping World
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Old 03-03-2013, 03:44 PM   #4
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I also keep an inexpensive voltmeter plugged in to an outlet at all times. Many marinas have low voltage that can damage some sensitive equipment.

AC Voltage Meter - Intersource Enterprises D10-170 - Voltage Monitors - Camping World
Of course, it is nice to have one that is readily visible beyond the panel too. I get UPS/Surge protectors that have a volt and frequency read out. In my case to easily monitor the generator without having to open up the panel, as I have Iso Boost transformers to take care of the shore power.

Out of curiosity, what do you do when it tells you the voltage is low?

A really good multimeter is absolutely invaluable, an essential tool for the cruiser. I got NewMar's, which measures all of the above and AC amps too. Over priced (they don't make it) but I was feeling flush that day and I trust them for quality. 5 1/2 years of heavy use:

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If I hadn't got this, I'd have gone with a Fluke.

I am not so sure I would use current measuring to validate ends of a cable. I use the continuity function. Another essential tool on board is some little alligator clipped jumpers. Clip one end to one of the the probes and the other to a length of wire and use that set up to track any kind of long cable, powered or not.
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Old 03-03-2013, 04:01 PM   #5
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Of course, it is nice to have one that is readily visible beyond the panel too. I get UPS/Surge protectors that have a volt and frequency read out. In my case to easily monitor the generator without having to open up the panel, as I have Iso Boost transformers to take care of the shore power.

Out of curiosity, what do you do when it tells you the voltage is low?

A really good multimeter is absolutely invaluable, an essential tool for the cruiser. I got NewMar's, which measures all of the above and AC amps too. Over priced (they don't make it) but I was feeling flush that day and I trust them for quality. 5 1/2 years of heavy use:

Test Equipment

If I hadn't got this, I'd have gone with a Fluke.
If the voltage is low and I just have an electric heater or kettle running I would not do anything but I shut off any electronics or switch them over to my inverter as I don't have a gen. I have seen voltage drop to 105 volts during high peak times (diner time). I use an Amprobe multimeter. They too are expensive but have great features and last forever, well almost!

Clamp on Meter Navigator™ Clamp ACDC-54NAV | Amprobe
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Old 03-03-2013, 04:15 PM   #6
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I too have a Fluke, have had for years, but for chasing live wires the DC clamp on was the hands down winner.

The Sears meter is a Craftsman, do you suppose the life time warranty applies to it as well as hand tools? I needed some large wrenches, car project, and Sears was the only place close that had them. I was very disappointed with the current "Craftsman" quality.

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Old 03-03-2013, 04:46 PM   #7
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I too have a Fluke, have had for years, but for chasing live wires the DC clamp on was the hands down winner.

The Sears meter is a Craftsman, do you suppose the life time warranty applies to it as well as hand tools? I needed some large wrenches, car project, and Sears was the only place close that had them. I was very disappointed with the current "Craftsman" quality.

Bob
OK, now I am curious about this. How are you sure the wire you clamp on is not some other wire carrying the same current load? Admittedly I have a fairly complex boat; this method seems to me that it would just narrow down the possible choices. Fortunately Hatteras numbered all their cables and provided the schematics, but it is stuff that subsequent owners added that can be frustrating. What am I missing? can you give a brief how-to? Thanks in advance!
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Old 03-03-2013, 05:02 PM   #8
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Of course there is no guarantee. But the meter does show current direction so that helps. Also turning loads on and off to vary the current helps. Sometimes you end up disconnecting a cable to see if the voltage goes away. Also cable size and color narrows it down somewhat.

It's not a simple one step procedure, you have to do some of the other steps for verification.

Bob
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Old 03-03-2013, 06:48 PM   #9
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Of course there is no guarantee. But the meter does show current direction so that helps. Also turning loads on and off to vary the current helps. Sometimes you end up disconnecting a cable to see if the voltage goes away. Also cable size and color narrows it down somewhat.

It's not a simple one step procedure, you have to do some of the other steps for verification.

Bob
Disconnect both ends of the cable and use the continuity function of your meter. That way, you're sure it's the same cable. Of course if the cable goes to a terminal strip with other connections, it still may not be the same cable. All the cables connected to the terminal strip will read continuity. (This is why electricians and electronic technicians command such high rates of pay. )
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Old 03-03-2013, 07:51 PM   #10
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A tool I found very useful is a wire tracer. I can disconnect the wire from the component in the engine room, connect this tool which sends a signal up the wire, and with a small receiver that you use to touch the wire at the other end, you can listen for the signal. It is not necessary to probe the bare end of the wire, just touch the insulation. The tool is made by Sperry and I got it at Home Depot. I think it was around $70.00
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Old 03-03-2013, 07:54 PM   #11
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A tool I found very useful is a wire tracer. I can disconnect the wire from the component in the engine room, connect this tool which sends a signal up the wire, and with a small receiver that you use to touch the wire at the other end, you can listen for the signal. It is not necessary to probe the bare end of the wire, just touch the insulation. The tool is made by Sperry and I got it at Home Depot. I think it was around $70.00
Those indeed work too, but I already have the multimeter. Networking and CCTV guys use those a lot.
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Old 03-03-2013, 08:04 PM   #12
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A tool I found very useful is a wire tracer. I can disconnect the wire from the component in the engine room, connect this tool which sends a signal up the wire, and with a small receiver that you use to touch the wire at the other end, you can listen for the signal. It is not necessary to probe the bare end of the wire, just touch the insulation. The tool is made by Sperry and I got it at Home Depot. I think it was around $70.00
I used one for many years in my job. They work, but they can lead you astray because the signal can couple to other wires. It takes some experience to use them effectively.
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Old 03-03-2013, 09:40 PM   #13
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(This is why electricians and electronic technicians command such high rates of pay. )
They make all that money because they can use an ohm meter? Who woulda thought it? And here I spent four years of my life to become an EE.

Sorry I started the whole thing,

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Old 03-03-2013, 09:41 PM   #14
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Disconnect both ends of the cable and use the continuity function of your meter. That way, you're sure it's the same cable. )
The obvious solution is to disconnect all the cables on the boat and start from scratch.

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Old 03-04-2013, 08:37 AM   #15
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One device that can be really useful is the circuit tracer that can "see" AC thru walls.

To make it a useful boating tool purchase an old style open doorbell in 12V that rings.

Discard the bell and use the vibrating contacts to make and break the DC circuit.

The AC current sensor doesn't care if its real AC or pulsating DC , so you can look thru boat walls .
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Old 03-04-2013, 09:20 AM   #16
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They make all that money because they can use an ohm meter? Who woulda thought it? And here I spent four years of my life to become an EE.

Sorry I started the whole thing
I feel for ya Bob. You try to give some good tip and get picked apart on some useless diversion or argument. Clamp-on ammeters are very handy. You can use them to see what amp loads various accessories are causing. Some will surprise you.

I've used mine on the main DC feed to my switch panel. Turn off all breakers and then turn them on one at a time to see what each is pulling. Great to see what is causing your grief.
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Old 03-04-2013, 10:01 AM   #17
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I feel for ya Bob. You try to give some good tip and get picked apart on some useless diversion or argument. Clamp-on ammeters are very handy. You can use them to see what amp loads various accessories are causing. Some will surprise you.

I've used mine on the main DC feed to my switch panel. Turn off all breakers and then turn them on one at a time to see what each is pulling. Great to see what is causing your grief.
Try to stay on topic.

I did not attack Bob, he read something into my post my post that I didn't put there.

A clamp on ammeter can be a great tool for mearuring current flow in a wire or cable. I did not say otherwise. It's not the tool of choice or even close for tracing cables.
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Old 03-04-2013, 10:13 AM   #18
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It's not the tool of choice or even close for tracing cables.

Now we know, the expert has spoken. I will go back to the boat and undo all my changes and start over the proper way. I guess I can go back to the way we did it before transistors and even ohms were invented, around the dinosaur extinction, when we used a battery and a buzzer.

Bob
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Old 03-04-2013, 10:38 AM   #19
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Try to stay on topic.

I did not attack Bob, he read something into my post my post that I didn't put there.
That's odd. I got the same vibe.

It's actually a a great tool for tracing loads through your boat. You just have to be willing to think it though. I've used one to label unmarked cables that snake around my engine room. Just secure all the other current flow (breakers) and then the only DC flowing in your boat would be on the cable you're following.

If you're feeling enough DC induced current to be confused about which wire it's on... perhaps you need a better ammeter?

And btw... I also have tone tracers. They work OK, but also can lead you astray if you're not thinking.
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Old 03-04-2013, 10:47 AM   #20
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I guess I'll be off the forum for a while. I'm going down to the boat to disconnect all wiring before somebody gets hurt. Then I'll get out my old lantern battery and buzzer and start over and do it right.

Here I thought that after almost sixty years dealing with electricals, electronics and such I actually knew what I was doing. I guess you're never too old to learn the error of your ways.

Bob
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