Sauna Cabin

[WightDiamond]

Hi all,

Never posted previously but check in from time to time and have a read, always something new of interest. Anyway been out to customer ,they  purchased sauna and then called me in .

Cabin has already been assembled into large out building with small sub board already in place- rcd protected ( lights/four sockets/small pond pump and pond lights)  fed from house DB in 3 core 6mm swa-buried!  

Property has overhead supply and has earth rod for main house distribution board. House DB has split board 30ma and 100ma main iso. Customer has also had problems with up and downstream rcd's between house and outbuilding(that can be dealt with ok)

Several issues here primarily the sauna manufacturer states heater must not be connected to RCD, i assume heating rods may get pitted or absorb moisture.ok so its special location but its all TT system so I'm thinking the following:-

Can i use present feed in SWA from house if i was to disconnect from present house DB and reconnect to new sub main via Henley blocks from incoming supply, new rod at outbuilding, rcbo's in outbuilding apart from sauna feed in 16amp breaker. The real question is will this method meet the requirement for the SWA  feed to be RCD protected?

Thoughts and brickbats this way 

WD

 

[Murdoch]

Several issues here primarily the sauna manufacturer states heater must not be connected to RCD, i assume heating rods may get pitted or absorb moisture.ok so its special location but its all TT system so I'm thinking the following:-

A bit surprised by that statement - can you post a link?

 

[WightDiamond]

ok so have read again the manufactures installation instructions , also have email reply from manufacturer as follows :-

3.3.1. Electric Heater Insulation Resistance When performing the final inspection of the electrical installations, a “leakage” may be detected when measuring the heater’s insulation resistance. The reason for this is that the insulating material of the heating elements has absorbed moisture from the air (storage, transport). After operating the heater for a few times, the moisture will be removed from the heating elements. Do not connect the power feed for the heater through the RCD (residual current device)

Now im not sure if this may have been lost in translation? im wondering if what they are actually indicating is method that drys out the heating elements? 

:shakehead

WD

 

[Blue Duck]

Lost in translation???

It's not a Chineseium element is it? 

 

[Murdoch]

Are you going to state this on your certificate, as to why you didn't use a RCD?

 

[Tony S]

The SWA, earth at both ends and sink a rod at the remote board. You will be extending the earth nest and therefore improving its effectiveness.

The manufacturer stating the sauna heating elements should not be RCD protected is totally irresponsible in my opinion.

 

[Evans Electric]

I think you HAVE to have an RCD in the circuit , whatever they say  to conform with the Regs . 

Can I suggest drying the elements out  via an MCB  ...UNDER TEST CONDITIONS...  then megger it  and insert RCD  .  If it starts tripping , I 'd say it was not of merchantable  quality  TBH   

 

[WightDiamond]

Are you going to state this on your certificate, as to why you didn't use a RCD?

if i was to state that it would not meet requirement for the swa feed to be rcd protected, so no. The manufacturers statement certainly surprised me but on second reading i believe they are suggesting method to enable elements to run and dry out. RCD the circuit, belt and braces will comply with this install.  I'm going email them again and see if my thinking on the elements is what they actually meant.

 

[Andy™]

i think Deke may be onto something, maybe its a badly worded and intended to mean if IR is low, dont connect to RCD, switch on and dry it out, then reconnect to RCD?

if it was my job, it would be getting an RCD and a complaint to the manufacturer

 

[binky]

think Deke is very correct, they are suggesting drying out element before RCD protecting cct.

I used to have same problem every xmas, the only time my wife ever used the second oven on our cooker. RCD trip every year, used to nurse it on for about 30  ins then it would be fine. I've now changed my board from shared RCD to RCBOs - no problems now. You could use say 100mA RCD on cable from house then RCBOs as sub board to try and keep intsall reliable.