Macerator Mystery

[JimPendoley]

So, my macerator would not spin up. I took it off the boat-a hideous task-took it apart at home and bench tested it off my car battery-very short distance (like a foot)seemed to work fine.

My batteries on the boat are charged fully-but I noticed that the macerator is listed as drawing 16 amps. The distance from my main panel is 40 feet (roundtrip) and the wire to the macrator was only 14 gauge. Off to West Marine and bought 20 feet of 8 gauge duplex. Ran the duplex from the panel to a new junction block and ran the last four feet from the junction block to the switch with 14 gauge as a temporary solution. Hit the switch and the macerator runs weakly then quits. The last four feet of 14 gauge wire gets a little warm. Would the insetertion of the last four feet of 14 gauge have negated the addition of 20 feet of 8 gauge? Need to double check the fuse too-I think I used a 15 amp fuse, but it might call for a twenty though it is listed as drawing 16amps. Maybe it has a higher surge requirement on startup?

[SimonV]

All good macerator pumps should have a fitting at the motor end of the shaft that takes a flat bladed screwdriver. From time to time the motor may lock its self in a position where it will not run, give the shaft a turn with the screwdriver and give it a go it should work.

[hellosailor]

Jim, if it draws 16 amps, yes, you want a 20A or 25A fuse. And you choose the fuse to protect the wiring, not the device. Forty feet round trip at 20A would call for 6AWG wire, not 8G, so even without the bit of thin stuff you're getting excessive voltage drop.

And a 20A fuse would be just fine in terms of protecting the 6AWG wire run, too.

But all it would take is one corroded fitting, or one half inch of punked out wire in the 14g section, to kill the power anyhow.

Motors all suck more power when they start up, they look like a dead short initially, but it would be able to get past that and spin up if there wasn't a bigger problem. Take a voltmeter and measure the voltage right on the contacts to the macerator. I'd guess that even with the motor running, it should be within maybe 1/2 volt of the battery voltage, unless there's a problem (corrosion, wire, contacts, bum motor).

If you repeat that test with the motor hooked up to a bench source or right to the battery and the results are different, then it definitely is a wiring problem.

[ebs001]

The fact that you say you took the macerator off the boat suggests that at one time the macerator worked with the existing wiring. So I would conclude that it was not a wire problem, although upsizing the wiring is a good idea. Check the voltage at the pump. If the voltage is good, test your pump wired directly to your boat batteries because they seem more likely to be your problem. If the voltage is low check all your connection and check the switch. There should be no voltage drop across the switch.

[JimPendoley]

The last poster was right on the money and shows the value of methodical thinking...

After spending 50 bucks on heavier gauge wire and rerouting and hanging all the wire securely, I hit the switch....and still had the same results. But wait....was that a wisp of smoke I saw coming from the momentary switch?
But its a heavy Cole Hersey momentary switch-how could that be the problem? Off to West Marine to discover that Cole Hersey makes two apparently identical switches-one rated for 10 AMPS and one rated for 35 AMPS-guess which one I had installed. I'd like to talk to the jerk who wired it all in the first place....oh that was me....

So, I had been running the macerator with undersized wiring AND an undersized switch, but fortunately on an adequate fuse and thankfully the switch was momentary otherwise I might have had a bigger problem (although the fuse would have blown before the circuit fried-hopefully.
Now the macerator runs like a champ on 8 gauge wire thru a 35 amp rated switch protected by a twenty amp fuse.
Thank you for all the suggestions-this forum is great!

PS the documentation that Jabsco ships with the unit indicated that 12 gauge would be sufficient for the run so 8 should be plenty

[erps]

PS the documentation that Jabsco ships with the unit indicated that 12 gauge would be sufficient for the run so 8 should be plenty

There was a thread here a month ago about a weakness in Jabsco macerators. Several members here have had them start leaking. It concerned me enough that I checked to see if mine was a Jabsco, and I was going to swap it out for the Shurflow and keep the Jabsco as a spare if my duty pump was a Jabsco. (Turned out to be a Shurflow as well as the spare)

[mitiempo]

Jabsco actually recommends 12 awg for a 40' run?

[JimPendoley]

My bad! Just double checked Jabsco installation docs and they recommend 8 gauge for a forty foot install (thats forty feet round trip!) Too many hours upside down in the vberth...It's a wonder the thing ran at all the way I previously had it wired.