Engel fridge - neutral & neg connection

[superheat6k]

My new boat has an Engel fridge but has only been connected to 12vdc supply. This morning I found a wiring diagram showing a common connection for both 12vdc negative and 240vac neutral.

Surely this will create a false earth path and could be dangerous if I plugged in to a reversed polarity shore supply. The entire bonding system would immediately become live.

Is this normal for Engel dual voltage fridges ?

 

[superheat6k]

I have managed to save the file with the Engel Wiring diagram as a jpeg - here.

I have never come across a direct link from 240vac neutral to 12vdc -VE.

This cannot be right, can it ?


I have come up with this isolation circuit to prevent any possibility of - VE and Neutral being connected at any time. Can anyone see anything wrong with the idea here ...

 

[Billjratt]

No doubt a certified sparks will advise further, but in a marina (UK!) you'll find neutral and earth are bonded and spiked at the head of the pontoon.
What's the issue?

 

[VicS]

My new boat has an Engel fridge but has only been connected to 12vdc supply. This morning I found a wiring diagram showing a common connection for both 12vdc negative and 240vac neutral.

Surely this will create a false earth path and could be dangerous if I plugged in to a reversed polarity shore supply. The entire bonding system would immediately become live.

Is this normal for Engel dual voltage fridges ?

You are right the DC-ve and AC neutral should not be connected together.

I would like to see the full installation/ operating instructions. Go ta link ?

However taking the diagram you have posted in isolation I would have assumed that the power input connector was designed so that only the ( special) 12 volt power lead OR the 240 volt lead could be connected at any one time and not both connected permanently.

In fact there does not seem to be any provision on the circuitry to recognise when 240V AC is connected and switch over to it!


AFAICS your proposed automatic change over circuit will be fine. Note the loop in the DC plug though.

David54321 will comment in due course hopefully.

 

[superheat6k]

You are right the DC-ve and AC neutral should not be connected together.

I would like to see the full installation/ operating instructions. Go ta link ?

However taking the diagram you have posted in isolation I would have assumed that the power input connector was designed so that only the ( special) 12 volt power lead OR the 240 volt lead could be connected at any one time and not both connected permanently.

In fact there does not seem to be any provision on the circuitry to recognise when 240V AC is connected and switch over to it!


AFAICS your proposed automatic change over circuit will be fine. Note the loop in the DC plug though.

David54321 will comment in due course hopefully.

I searched hi and lo for the diagram as the Engel standard manual has no useful electrical information with it. My new boat would not switch over to 240v, which turned out to be due to there being no 240v connection. I will have to pull the fridge out to find out if it will accommodate 240v (it should !), but if the diagram I have found is standard for Engel then obviously I am concerned.

As incidentally should any one else be who has one if this diagram is 'standard'.

Not sure what the 12v link is for. Any ideas ?

 

[VicS]

I searched hi and lo for the diagram ................
................................................ if the diagram I have found is standard for Engel then obviously I am concerned.

But no cause for concern if the design prevents you from connecting both 12v and 240v inputs at the same time

I am assuming that this is a portable unit designed to be plugged into whichever supply is available