Discuss three phase board separation in the Commercial Electrical Advice area at ElectriciansForums.net

It's 30mA, if you zoom in a bit you can see it.
OK, that sort of confirms it.

The best suggestion is from @westward10 and as it looks like a Hager board you can probably get RCBO for the single phase circuits easily enough. However, I'm not sure you will find a RCBO to replace the 3-pole MCB in that board (and no space for another pole beside it) so your best/cheapest option might be:

  1. Replace the RCD incomer with a switch (4P matches, but 3P might be fine).
  2. Replace the single pole MCBs with RCBOs for all circuits needing that protection (sockets, lights, etc)
  3. Put the RCD incomer from (1) in to a "garage CU" enclosure to provide separate protection for the 3-phase supply to the sauna.
Maybe others will have better ideas?

It might be worth inquiring of the sauna company what sort of RCD protection the recommend, as 30mA might be less than normal for that sot of load (assuming cable route does not require it).
 
Last edited:
OK, that sort of confirms it.

The best suggestion is from @westward10 and as it looks like a Hager board you can probably get RCBO for the single phase circuits easily enough. However, I'm not sure you will find a RCBO to replace the 3-pole MCB in that board (and no space for another pole beside it) so your best/cheapest option might be:

  1. Replace the RCD incomer with a switch (4P matches, but 3P might be fine).
  2. Replace the single pole MCBs with RCBOs for all circuits needing that protection (sockets, lights, etc)
  3. Put the RCD incomer from (1) in to a "garage CU" enclosure to provide separate protection for the 3-phase supply to the sauna.
Maybe others will have better ideas?

It might be worth inquiring of the sauna company what sort of RCD protection the recommend, as 30mA might be less than normal for that sot of load (assuming cable route does not require it).
Thank you very much for your answers. That helps a lot to understand which is the best option. And if anyone else has any other options i would like to hear them please.
 
This is what you need to replace the rcd switch.
So I have to replace all mcb's to rcbo's and replace rcd to this switch? What about the 3P mcb?
 
Yeah, my idea would be to find the fault that causes it to trip when water is poured on the stones in the sauna. This sounds like a definite link has been made between this action and the tripping of the RCD, so it needs to be investigated.
Yes, a couple of things to find out, such as did it always do this? (i.e. is a 30mA trip too low for that sort of installation) or has something changed.

It might not be the actual sauna heater of course, it could be that a light in the sauna is letting steam in and causing the earth leak. Maybe someone put in a replacement without suitable IP ration, or maybe it has special seals around them that have degraded with time, etc.?

That is the problem with a single RCB and intermittent trip - they might find it is actually a light circuit or similar that is causing it to trip.

Maybe @Vinnie2020 can get them to run it and make it trip then quicky isolate all the MCBs and see if an insulation tests reveals a leaky circuit before it dries out.
 

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