D51 Breakers?

[Top Hatt Craig]

Changed out a toilet on our '78 DC and the new one exceeds the capacity of our 30A D51 by 10 amps. I'll call Sam's Monday but welcome the wisdom found here in the mean time. Thanks, Craig

 

[Boatsb]

A 40 amp toilet. That's power.

 

[Top Hatt Craig]

A 40 amp toilet. That's power.

It's a Thetford (Tecma) 'Silence plus' macerator toilet (Italy) Claims to pump 33' vertically or 270' horizontally, neither of which we need it to do. I should have spotted the 40A draw in the fine print - my bad.

 

[MikeP]

Sadly, you can't just change to a higher-rated breaker. A 50A breaker on a 30A circuit will just turn the wiring into a heating element. IOW it becomes a fire hazard because the breaker can take more current than the wire can which is the opposite of what is supposed to happen.

SO...if you are going to use that 50A head, you are going to have to run new suitable gauge wiring to handle that load -remember to calculate the total length of the run (both ways) to determine the gauge. You MIGHT be lucky, depending on Hatt's original wiring gauge. Do the calculation (50A/voltage + distance) and MAYBE that wiring size is what was used. But I doubt it.

Here's an on-line calculator: https://bulkwire.com/help/recommended-wire-gauge-calculator

 

[krush]

Why not see if it blows the existing breaker first?!!??

Remember, breakers protect wires...overloads protect motors.....lol that was a professor krush lectures this past summer.

 

[Boatsb]

At the breaker what gauge is the wire?

Is it one wire to the head. Same size both ends and not powering other items?

What is the estimated length (out and back ) ?

A 40 amp breaker will need a larger wire than a 30 BUT hatteras is famous for over building.

Do the research and then the math.


By the way don't put a 50 in there either. It's too much.

 

[jim rosenthal]

270 feet horizontally? I think they are aiming at the mega yacht market. Wow.

 

[Scarlett]

If you have a clamp on amp meter I would try the toilet with the existing breaker check amp draw. Probably will be way less than 40 amps, especially if you are not pumping any where near the distances that the specs say the toilet can pump, especially the height. My guess on that head would be 20 amps max. John

 

[Top Hatt Craig]

Great suggestions, thanks all. I should have mentioned the new pooper trips the 30A Haster Head breaker two out of three tries, but has not popped the 30A fuse on the new toilet controller. The wire coming from the breaker (#38 two gage?) is 12' long round trip and definitely "over built" and will easily handle 10 more amps. Nothing else is powered down with the Master Head Breaker off. Hopefully I can buy a direct fit 40 amp breaker. If anyone knows where else to look that would be great.

 

[SEVEN]

Craig, post a photo of the toilet installed. Show how nice it is.

 

[Boatsb]

2 ga. That's gas motor battery cable.

If that's the true gauge then as a critical system (broken toilets are bad) at 3% voltage drop it's good for 120 amps. Make sure the ground is also 2 ga.


By the way seriously as a non critical system 5ha5s probably good for a 40 or 50 foot run at 120 amps (10% drop)

 

[MikeP]

If that's the cable going to the OEM head, then calling Hatt wiring "overbuilt" is a huge understatement!

 

[SEVEN]

If that's the cable going to the OEM head, then calling Hatt wiring "overbuilt" is a huge understatement!

That's Hatteras for you. Glad to be an owner.

 

[Top Hatt Craig]

Got a NOS 40A breaker from Mac's Electrical Supply through Amazon ($35) now all is well with the Master Head. One small problem was the new toilet's wast tank level sensor looks for continuity, and as you savvy bowel movers know our boats send a voltage, so a small 12v relay does the conversion for us and didn't mind being on overnight for test. We are looking forward to reduced pump outs as this toilet uses significantly less water in the low flush mode.