3 phase immersion heater fault

Phil.x

Hi all, I have a 3phase element connected in star, no neutral, with an earth fault on one of the elements.

I know I can adjust the connections so I can have 2 phases and one common neutral linking the other ends of the elements, and have the faulty element electrically disconnected.

Question I have but I think the answer is no, is, can I have 2 phases connected and link out the other end of the 2 elements with a bit of cable instead of the neutral.

2011

Is the element a single unit or are there 3 separate elements?

Bruthal.

You can do what you suggest. It will give about 50 percent of the full working setup. With neutral connecterd it will give 66 percent.

All assuming you can get at connections to modify.

Phil.x

https://www.boards.ie/discussion/comment/117992699#Comment_117992699

3 separate elements, starred using metal links.

2011

Disconnect phase and neutral from the faulty element and you can use the other two. Obviously it will only provide ⅔ output

2011

Apolgies, I see this was already responded to. As above I am assuming the common neutral is connected.

Phil.x

The black phase element was shorted to earth and its corresponding top left connection. So I left the links from the top middle and top right connected and lugged on the neutral and disconnected the black from the isolator and disconnected and taped up the element end lug... luckily.

It's working fine on two phases, but I had a guardian angle looking down on me today.

The breaker was tripped (by the faulty element) and I switched off the isolator (there are three 3phase elements and three isolators) before I done the repairs, and as it was near 4pm home time, I had this feeling of doubt and just thought to leave it until Monday before switching on the power and maybe do another megger test, but no I turned on the 3ph breaker and went back and started to do a continuity test for whatever reason which was OK but I got that buzzing sound from the fluke when it detects power, right enough there was 380v at it, the cowboy house bashers who installed it labeled the isolators wrong. I was so fcuking close to a big shock, but I'm happy that I taped that lug and i always check with the fluke as I go along.

Bruthal.

Once the neutral is connected you have 66 percent of the full 3 going. Without neutral it would have been 50 percent as said.

Never trust labels no matter if it was cowboys or a genius. They are more useful as a guide than proof of what breaker does what. Switch off/on/off etc and prove by test.