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

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)

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

LaBomba said:

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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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.

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.

caltexflanc said:

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.

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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

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

BobH said:

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

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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!

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

BobH said:

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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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. )

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

Russell Clifton said:

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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Those indeed work too, but I already have the multimeter. Networking and CCTV guys use those a lot.

Russell Clifton said:

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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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.

rwidman said:

(This is why electricians and electronic technicians command such high rates of pay. )

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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,

Bob

rwidman said:

Disconnect both ends of the cable and use the continuity function of your meter. That way, you're sure it's the same cable. )

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The obvious solution is to disconnect all the cables on the boat and start from scratch.

Bob

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 .

BobH said:

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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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.

SomeSailor said:

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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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.

rwidman said:

It's not the tool of choice or even close for tracing cables.

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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

rwidman said:

Try to stay on topic.

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

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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.

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

Do clamp-on ammeters even work on DC current? I thought they were AC only. I thought the flux field around the wire was all they could measure and to measure DC, you have to have a shunt. Wow... a DC clamp-on would indeed be a cool tool to have.

AC clamp-on works like a transformer. DC clamp-on uses a Hall Effect device to sense the static magnetic field caused by DC current flow.

But beware, according to the "experts" in previous posts it's a totally worthless device.

Bob

Well I'll be slapped silly. Learn sumptin' new every day. Might haffs to gets me wunna dem. Thanks.

Here's what I bought CL-2000

True RMS 400 Amp AC/DC Digital Clamp Meter-CL2000 at The Home Depot

Much better than my older Sears one...but double the price (more feature too)

BobH said:

But beware, according to the "experts" in previous posts it's a totally worthless device.

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See... it's you "round earth" types and yer new-fangled "hall effect" theories that have put bell-buzzer manufacturers around the world out of business.

This is more of a voltmeter and results are about binary, but it does ok. Only Gene Simmons could test my house bank, though.

BobH said:

AC clamp-on works like a transformer. DC clamp-on uses a Hall Effect device to sense the static magnetic field caused by DC current flow.

But beware, according to the "experts" in previous posts it's a totally worthless device.

Bob

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Where did someone say that? I called it an "invaluable" "essential" device myself.

I just hadn't seen the clamp on used as a tracer and was interested how it was done. Sorry if somehow that was of offense. Otherwise, I think we may be violently agreeing with each other.

Bob, Thanks for the great tip! No good deed goes unpunished by some!!

I bought one to track currents in the wiring mishmash the PO left, but being an absolute green horn in electrical stuff I really am glad to pick up useful tips like this anywhere I can. Thanks for putting the original post out there.

Shows what I know about electricle