6Kw Sauna

[new_spark]

Hi

I apologise in advance for lack of knowledge i this subject as I only work in domestic, a mate owns a commercial gym and has a 6 Kw sauna heater which comprises of 3x 2Kw elements.

He asked me to look at it as he has fallen out with his normal electrician over prices, he told me that he has had a few problems with it in the past which is normally related to the elements failing.
The fault as described to me was that it just wasn't working.

I started at the board which is a 3 phase board, the sauna is on a single phase 40A RCBO, which was in the off position, after isolating the supply at the RCBO I traced the 10mm T+E to a 45A DP Switch which was checked and isolated.

I then dismantled the heater and checked continuity on all of the elements, all appeared to be working, then I traced the wiring back from the heater which is some type of heat flex it has 6 cores and earth and appeared to be 3 line conductors and 3 neutrals. I then followed the cable back to a IP enclosure which was on the side of the sauna in quite a humid area, the cover was off and I found the mess in the picture, no wonder the RCBO had tripped!

The contactor is a Moller Dil 1M, it appears to overheated on the neutral supply side which is fed in 10mm T+E going back to the 45A DP switch as mentioned earlier.

My questions are, why would the original installer have fitted a contactor, it's not high voltage switching and more importantly, why has it over heated? The cable sizes would all appear to be correct and judging by the heat damage the RCBO has only blown when the Neutral cable has burnt completely through and broken the link.

I have disconnected the entire supply from the board and removed the contactor, I've told him its beyond me and told him to get the yellow pages out!

 

[GLENNSPARK]

loose neutral....

 

[malcolmsanford]

I would imagine the neutral was loose as Glen said, you'll find that 95 times out of an hundred it is always the neutral.

Also it's not high voltage why you fit the contactor, but an high load. As this box is fixed to the unit, was this not part of the manufacturers control system?

I would imagine that the switch which is double pole or even single pole is controlling the contactor coil, so it can switch all 3 elements on via this

 

[new_spark]

loose neutral....

Thought that myself but the neutral is still tight in what remains of the contactor!

 

[new_spark]

I would imagine the neutral was loose as Glen said, you'll find that 95 times out of an hundred it is always the neutral.

Also it's not high voltage why you fit the contactor, but an high load. As this is box is fixed to the unit, was this not part of the manufacturers control system?
I would imagine that the switch which is double pole or even single pole is controlling the contactor coil, so it can switch all 3 elements on via this

Thanks for the reply, the smaller flex you see in the pic comes from the timer and is controlling the switching element of the contactor, you may be right in that it is part of the installation instructions but it looks a bit DIY to me the IP enclosure doesn't look big enough to house the contactor perhaps why the cover was off? I wouldn't have thought that the load, 26A, would be classed as a high load?

 

[new_spark]

This is a pic of the other end of the contactor if it helps.

 

[Guest55]

must admit the wiring in the last pic doesnt look factory fitted.
What rating was the contactor ?
dont suppose it matters now , it needs replacing and he cable re-making off anyway.

 

[sedgy34]

same as glennspark LOOSE NEUTRAL

 

[JD6400]

Loose neutral in on the contactor terminal inside on the bridge piece , and not on the cable terminal then , never the less thats a lose neutral .
It all looks good to me and factory standard , don't forget it is the thermostat that is switching the load so would you put that 26A straight through it or go through the contactor instead ?
If you go on the net , there are plenty of suppliers about for this sort of kit , i have just brought a new 8KW heater and remote controller like this to replace one on my own sauna , it was a Oceanic which seems to be good i also have a Oceanic steam generator in a shower in the same bathroom that has been going strong for several years now !

 

[new_spark]

Loose neutral in on the contactor terminal inside on the bridge piece , and not on the cable terminal then , never the less thats a lose neutral .
It all looks good to me and factory standard , don't for get it is the thermostat that is switching the load so would you put that 26A straight through it or go through the contactor instead ?
If you go on the net , there are plenty of suppliers about for this sort of kit , i have just brought a new 8KW heater and remote controller like this to replace one on my own sauna , it was a Oceanic which seems to be good i also have a Oceanic steam generator in a shower in the same bathroom that has been going strong for several years now !

Thanks for the reply, just had a good look at the contactor and the neutral grub screw does appear to have been loose as you have all said!

My only other concern is why is the CPC in the A2 terminal on the 2nd pic, shouldn't the A1 and A2 be line and neutral respectively?

 

[JD6400]

Had not looked at your second picture , somebody's been a naughty boy !::

 

[Knobhead]

No! A1 is from the thermostat, A2 neutral.

 

[new_spark]

Think i need to trace the CPC back to see if its been used as a neutral and not sleeved correctly and connected to a neutral some where, forgot to mention that the smaller black flex powering the contactor which is a 3 core and earth with the CPC being in A2, is supplied from the timer which is connected to a separate single phase board to the main sauna heater, surely that shouldn't be so??

 

[new_spark]

What's everyone's opinion on this, is a case of just a straight swap of the contactor that I should attempt or is it more involved and as I initially said in OP, leave it to someone more experienced?

Thanks

 

[PC Electrics]

In that case the control box should have a warning label to isolate at two points (and preferably identifying those two points). You could isolate the main 40A and still have a live coming in from the timer.

Personally I'd have fused down from the 40A to supply the timer. It could be included in the enclosure and a 4 core run to the timer (L,N,E & SL back).

You say the box is in a humid area, but what about the 45A switch? Is that the 'cooker' type or a rotary job or something else? And is that in the humid area?

Like the others said I'd suspect a loose connection (often a neutral) but it could be some of that humidity got into the enclosure and that wouldn't have helped. So you might need to replace the enclosure.

 

[JD6400]

It would appear to have been bodged when it came to the field wiring , there should be only the one feed to it and as far as i am concerned , anyone that uses a cpc for a line conductor , be it sheathed or not , needs dragging outside and shot ( preferably after a good kicking for being such a badger !) .
If memory serves me correct you may need to fit a door switch now as well or you will be contravention of some new brussel sprout rule or something !

 

[PC Electrics]

I have disconnected the entire supply from the board and removed the contactor, I've told him its beyond me and told him to get the yellow pages out!

I hope you weren't so un-diplomatic! You could have said that as you're newly qualified, you haven't dealt with such a system before so you need to get some more information and maybe some help.
Get the sauna fixed for your friend and some learning for yourself.

I'd be willing to help if you wish to discuss terms. I'm less than an hour from you, though there must be someone here who's nearer.

You're to be applauded for asking though. There's many who would have just bodged their way through it and learnt nothing.

 

[PC Electrics]

It would appear to have been bodged when it came to the field wiring , there should be only the one feed to it and as far as i am concerned , anyone that uses a cpc for a line conductor , be it sheathed or not , needs dragging outside and shot ( preferably after a good kicking for being such a badger !) . AGREED
If memory serves me correct you may need to fit a door switch now as well or you will be contravention of some new brussel sprout rule or something !

Door switch eh? is that to turn off the heaters if the door is left open then?

 

[new_spark]

Yes the 45A switch is also in the humid area coincidentally the face plate was also unscrewed from the surface box! I've got to go out now, take the good lady out for a meal but I will let you know on that offer PC, need to know more about the control unit on the outside of the door as well!

Cheers

 

[Knobhead]

If you will pick me up in Nottingham (I can’t drive now) I’ll have a look for you. a couple of pints in the big Forester’s and your sorted.
You're doing the work!
PM me.

 

[JD6400]

If it is in commercial use then i believe it is the law now .
So it is prevented from waisting to much energy with the door left open .

 

[JD6400]

If you will pick me up in Nottingham (I can’t drive now) I’ll have a look for you. a couple of pints in the big Forester’s and your sorted.
You're doing the work!
PM me.

Tony , your a good man , if i remember right this is not the first favour you have offered with the Foresters en route !:54:

 

[Knobhead]

I'm cheap, and so is the beer!

 

[Knobhead]

But it's as good as me :sad_smile:

 

[JD6400]

Just good value for money !:wink5:

 

[Knobhead]

Tony , your a good man , if i remember right this is not the first favour you have offered with the Foresters en route !:54:

The Foresters is on the way back once we’ve sorted out what needs doing. I may be an old soak but there’s thing you have to keep in the right order.

I’m more than happy to help new_spark, but it will be pointing the right direction, not me doing the job.

new_spark, I’m not the two headed ogre that some will have you believe. Sometimes I’m almost human!
The biggest factor is if we need cable and/or a contactor. The contactor is an off the shelf item, the cable??? One thing is for certain the contactor has to be outside the sauna, preferably near to the control unit. Unlike someone suggested the heat doesn’t cut off as the door is opened. Does your oven at home cut off when you check on the roasties?

Drop me a PM

 

[JD6400]

If you goggle " Oceanic oc-sa ll instructions " this will give you some ideas of what is needed , this is the one i have .
The cable will need to be at least HO7RN-F , as for the door switch Tony it was a note on a separate piece of paper that came with the controller saying it was now a requirement if being fitted on commercial sauna's , I can only assume it is to stop people just leaving the door wide open and the sauna on after they have finished ?
The controller can either be factory built in to the heater or on the outside of the sauna only !

I think i will have to grab a bottle of Batemans out of the fridge and me copy of the regs and go for a period of contemplation in the sauna now ! Good call what ?