ETA Circuit breaker protection - Quick Q.

[OldLady]

Hi there,

Well, first post and I'm sure it's going to be one of many. I'm not a qualified sparky but a pretty handy enthusiast who does plenty of research and investigation before I start any elec work.

I'm about to start wiring up a boat project I've been working on for the past 24 months. Its been a long time in the planning and I've procured all my electrical bits and just have to get the lot installed.

I'm going very much OTT on the wiring (in terms of the required mm2) which will all basically be 12v, with a bit of 240v from an Victron inverter combi unit (3kw/120amp charger).

I've bought a decent set of ETA 3120 series thermal breakers (google ETA 3120) for the DC distribution panel.

Now I just wanted to try and clarify something with regards to the various types I have. Some of these are SPDT and are thermally protected on 1 load and the other load is "unprotected". Now as far as my knowledge goes, the protected load output will cause the breaker to trip, whereas the unprotected side will not cause the breaker to trip and the unit purely acts as a switch from any appliance on this pole?

I cannae post a pic or link as I haven't got enough post yet, sorry.

Many thanks in advance and a Merry Christmas to all. :teeth_smile:

 

[Geoffsd]

Some of these are SPDT and are thermally protected on 1 load and the other load is "unprotected". Now as far as my knowledge goes, the protected load output will cause the breaker to trip, whereas the unprotected side will not cause the breaker to trip and the unit purely acts as a switch from any appliance on this pole?

I cannot find any DT ones but, if what you quote is correct, the other terminal could provide a warning when it trips.

I found some DPST ones where only one pole is protected.

 

[OldLady]

Thanks, yes you completely correct, getting my terms mixed up, yes they are DPST, apologies.

I was just slightly confused as to why you would want the other pole to be unprotected?

 

[GLENNSPARK]

Thanks, yes you completely correct, getting my terms mixed up, yes they are DPST, apologies.

I was just slightly confused as to why you would want the other pole to be unprotected?

is that Mrs. Brady.....
i`m sure i saw you once in a comic....

 

[Geoffsd]

I was just slightly confused as to why you would want the other pole to be unprotected?

To also isolate the negative in the event of a fault, I would think.

 

[OldLady]

Using it as a warning circuit, to a indicator light makes perfect sense now. So it'll be on when the breaker is on and if the appliance on the protected pole trips, both it and the light will be out. Perfect for for out the way appliances that you cant see. I can see the light as it were.