240v heating element connected through 2 phases?

[sibbits]

i was asked to check why a tank heater was not working properly today an came across something im pretty sure is wrong. but was wondering if any of you had any thoughts on
the element 240v rated was connected to two phases (one at each teminal ,no neutral) via seperate breakers, i dont know how long this had been the case .its now isolated till i fathom it out:banghead:
is there any reason why somone would do this??
its puzzling me?
the element seems to have good continuity and is showing 250M ohms to the metal casing

 

[Knobhead]

It’s OK showing the IR reading, CR would be more useful. If the element has survived then it’s a simple enough job to swap one line to the neutral.

PS. You sure it’s a 230V element? I’ve fitted plenty of 433V immersion heaters.

 

[Marvo]

If the element tests fine this wouldn't explain you original fault of the heater not working.

 

[sibbits]

i have re jigged the wiring yesterday to make it 240v so now the cal controller is switching on an off as it should.
CR?? continunity readiing?
i cant get these readings at the mo as the test rig is running and the terminals / rating cap are right next to a spinning belt.
just puzzled me as to the thought process of whoever put it in
i cant do any further investigations till the rig stops.

 

[Marvo]

just puzzled me as to the thought process of whoever put it in

You can run element tubes on voltages other that those stamped on them. You need to calculate the tube surface temperature which depends on several factors such as the heat density of the element, the tube surface area, the material the tube is made from, the fluid or medium the element is immersed in etc etc. The fact that your element is still in tact after prolonged running on 400v suggests someone may have done these calculations and specified 400v as the design voltage. By reducing this voltage you may be impairing the functionality of the system as a whole.

 

[sibbits]

Ive checked the other test rigs and this is the only one running 2 phases thru the elements.
The previous maintenance sparky had a rep for being a bit rough.
The elements are heating 15w40 diesel oil.
This post was more of a wtf ?moment , so i was kinda passing it out to the collective minds to see what they thought.
Once this rig finishes its tests ill have a chance to see what the details are.
More news at 11

 

[PEG]

Just out of curiosity,were the "two separate breakers" linked? and did you identify the fault? :wacko:

 

[sibbits]

installed 2 new 240v heaters and re jigged the wiringarty:
the old ones when taken out and checked more thoroughly were bad they were breaking down)so not working properly.it took a while for down time to remove the tanks and heaters to allow proper testing servicing to be carried
out
.

 

[DPG]

Good to get feedback. Too many threads get left hanging. Daz