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Insignificant wiring problem?

Feb 20, 2011
7,783
Island Packet 35 Tucson, AZ/San Carlos, MX
I'm hooking up a new WEMA water level gauge sending unit on the tank. It appears there's no wrong way to connect the wires, as the dial jumps up when either of the wiring possibilities is temporarily connected up.

Anyone know if I'll be sorry if I connect the black to the red or the yellow?
 
Jan 11, 2014
7,826
Sabre 362 113 Fair Haven, NY
Yellow is the new black according to ABYC. So, I would connect the yellow from the sensor to the black wire and red to red (or what ever color is the positive).
 
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Likes: justsomeguy
Sep 25, 2008
923
Macgregor & Island Packet VENTURE 25 & IP-38 NORTH EAST, MD
From the WEMA website

Q: How does the 2 wires from the senders connect?

  • Black wire connects to the gauge; pink wire connects to the ground. The sender draws power through the gauge connection.

On my IP, I had a red and yellow wire running to the old sender that came from the gauge. I connected the black sender wire to the red gauge wire and the pink sender wire to the yellow gauge wire. I did not ground to the tank. It works fine this way.
 
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Oct 26, 2008
5,011
Catalina 320 Barnegat, NJ
I'm hooking up a new WEMA water level gauge sending unit on the tank. It appears there's no wrong way to connect the wires, as the dial jumps up when either of the wiring possibilities is temporarily connected up.

Anyone know if I'll be sorry if I connect the black to the red or the yellow?
Let us know if you figure it out. I had the same response, the dial indicator jumps to the limit either way. My water tank was empty. I figured that something was wired incorrectly at the gauge end because I don't see the little backlight on. I wired it just like the way the fuel gauge looks but I lost the instructions for the water gauge and gave up trying to figure it out. That was a while ago and I forgot about it until you had to mention it. Now that it is winter, I might try again if you can provide the answers! :confused::confused:
 
Jan 11, 2014
7,826
Sabre 362 113 Fair Haven, NY
Actually I don't think it matters much which way the wires are connected, other than maintaining some consistency with the color coding.

If you have this kind of sensor http://www.wemausa.com/sensors/level-FuelWater.shtml it is basically a very fancy variable resistor. Instead of changing the resistance through some kind of conductive medium, they use a series of reed switches that are activated by the float. The lower the float the longer the wire. the higher the resistance the lower the needle points. The gauge is basically a volt meter. Full tank, little resistance, higher voltage, the needle goes up. Low tank, higher resistance, lower voltage, needle points down. And all points in-between.
 
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Likes: JamesG161
Feb 14, 2014
5,705
Hunter 430 Waveland, MS
Last word, you have to know if it is USA or European wiring standard.

USA has live zero and is reversed
European is different [mine of course] 0 volts is dead or level zero.
Wema site show how to tell which you have.
Jim...
 
Jan 11, 2014
7,826
Sabre 362 113 Fair Haven, NY
Sorry, Dave, but it does matter.
Jim...
This is one of those, "we're both right." When measuring resistance it doesn't matter which way the current flows. However, gauges can be wired differently. The European standard is different from the US standard both in terms of amount of resistance and whether low resistance means the tank is full or empty.

So, it does matter which gauge you have, but it doesn't matter which way it is wired if you have the correct sender for the gauge. Matching the sender to the gauge is the important detail.
 
Feb 20, 2011
7,783
Island Packet 35 Tucson, AZ/San Carlos, MX
From the WEMA website

Q: How does the 2 wires from the senders connect?

  • Black wire connects to the gauge; pink wire connects to the ground. The sender draws power through the gauge connection.

On my IP, I had a red and yellow wire running to the old sender that came from the gauge. I connected the black sender wire to the red gauge wire and the pink sender wire to the yellow gauge wire. I did not ground to the tank. It works fine this way.
Recently did just the opposite. It seems to be working fine, but there's enough wire to cut and re-do if my gauge starts going up while emptying.
Will report back if it snafus, @Scott T-Bird , and it's USA ohms @JamesG161 .
Thanks all.
20181220_163228[1].jpg
 

Tom J

.
Sep 30, 2008
1,993
Catalina 310 Quincy, MA
This is one of those, "we're both right." When measuring resistance it doesn't matter which way the current flows. However, gauges can be wired differently. The European standard is different from the US standard both in terms of amount of resistance and whether low resistance means the tank is full or empty.

So, it does matter which gauge you have, but it doesn't matter which way it is wired if you have the correct sender for the gauge. Matching the sender to the gauge is the important detail.
Thank you! I tried to explain that to the owner/skipper of the boat I was working on as a mechanic. He insisted we get new sending units and connect them to existing gauges. Sure enough, most of them were reversed; empty meant full, warm meant cold, etc. The fix was to mark the correct readings on the dash panel with magic marker.
 
Feb 20, 2011
7,783
Island Packet 35 Tucson, AZ/San Carlos, MX
Update. Seems I used a quarter of the tank to take a shower...:badbad:
20181224_075400.jpg
Oddly, it was reading slightly less full yesterday.
 

genec

.
Dec 30, 2010
188
Pacific Seacraft Orion27 HP: San Diego, M: Anacortes
I just want to know if his wife found the car keys...
 
Feb 20, 2011
7,783
Island Packet 35 Tucson, AZ/San Carlos, MX
Yah, car keys found.
Another update: after a spirited sail, the hydrates in the bottom of the tank caused the float to stick on the shaft. Read zero agua until I cleaned it.

Edit- now she's lost her hat and gloves. :banghead:
 
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