Sauna and steam room

[ErnieH]

Hi everyone!

I would be really grateful for some broad advice if anyone can spare the time.
 

I’m planning on building a sauna and steam room (2 separate rooms). I’ve been through the sizing and the sauna would use a 7.8kw heater and the steam generator would be 6kw. 
 

Because it will be in the basement and the whole of the remaining ground floor is block and beam construction, it is possible to pull new cable through under this floor where it is nice and cool, so running in whatever thickness of cable shouldn’t pose the contractor any problems (I’d be happy to get the cable routed with/for them). The run is probably in the region of 10m back to the consumer unit.  
 

Ideally both heaters would be able to be used at the same time so you could go from one room to the other, already heated. I’ve read and kind of understand the diversity thing but I’m considering that when first switched on to warm up, the sauna would be going flat out for maybe 45mins. The steam generator would probably be intermittent (if my visits to the sports centre are anything to go by anyhow) and a session would probably last about 2 hours overall along with heat up. 
 

I’m just wondering if this type of load would be ok along with all the other appliances in the house, we have pretty much all appliances, big amp for tv sound, American fridge and what have you. Also a couple of kids so there are a few big TVs on and computers and what have you. 
 

The consumer unit show a max 100a allowed, I’m not sure about the main fuse as I can’t find the thing to open it and have a look so will have to pick one up. I’m guessing it’ll be 100a also as the consumer unit is from when the house was built so I doubt they would put a 100a one in if the main fuse was 60a as it would probably cost more I’d guess?

I’d be really grateful for general thoughts on this before I call someone out and potentially waste their time. Also, if it sounds feasible, would they need to go on two separate circuits or could they be split from the one? Only ask this as I have just one space left on the CU so might have to consider retiring the electric shower if they need their own (been dying to change to a rain head anyway). 
 

Thanks for looking, hope it’s a straightforward question to those that know and hope I’ve provided sufficient detail. 

 

[binky]

Do NOT open the main fuse, apart from being illegal, it's als.o dangerous.

So your main question is 'will this overload my system' . Bit hard to evaluate with what you have posted, but unless you like to sauna, steam and cook at the sme time you will probably be OK?

 

[ErnieH]

Hi Binky

Thanks for the response. I think you’ve misunderstood, I meant I haven’t got the key to open the white box outside, I assume there’ll be marking on the main fuse stating the amps?

 

[NozSpark]

You definitely need to get someone out as you're planning on adding about 60A to the demand of your electrical installation, I doubt that you'd be able to supply this from your existing consumer unit

Also, even if you do get a cabinet key, any amperage label on the main fuse holder will only state the maximum size of fuse that it can take... they very commonly have a 100A label and only a 60A or 80A fuse.... you may very well need an upgrade to your supply 

 

[ErnieH]

You definitely need to get someone out as you're planning on adding about 60A to the demand of your electrical installation, I doubt that you'd be able to supply this from your existing consumer unit

Also, even if you do get a cabinet key, any amperage label on the main fuse holder will only state the maximum size of fuse that it can take... they very commonly have a 100A label and only a 60A or 80A fuse.... you may very well need an upgrade to your supply 

Thanks for this NozSpark. Is there any way to tell what my supply is before calling someone? If it’s not anywhere in the cabinet or on the fuse, would the electric company have details or would someone need to test it?

Assuming that the supply was 100a (and the CU states max of 100a) would you think this would come out as OK or would calculations need to be done as to our current usage? 
 

Looking at the model of electric shower, that is between 8.5 - 10.5kw (doesn’t state which on the front) so would getting shot of that help a lot? It’ll be going in time anyway. 
 

Finally, I’m going to take a wild guess and say that having the supply upgraded is probably prohibitively expensive and assuming the supply is already 100a, this is as high as it can go isn’t it? 
 

If the supply isn’t sufficient I’m wondering what my other options are, would the 7.8kw sauna heater alone be OK? (It would be around the same as the shower) and if that was Ok but not both together, is it possible to have some kind of switch that only allowed one or the other of the sauna or steam to be used? This isn’t what I’d hoped for but it’s a better solution than not having them. 
 

As to the consumer unit, it does say that it’s 100a but I wouldn’t be adverse to paying to have this changed over if there was good reason, it would be in the region of 35 years old now so maybe is due a change anyway?

Thanks again, it is really appreciated. 

 

[Murdoch]

TBH none of can really comment without really looking at the actual installation etc

So continually looking at forums won't give you a clear idea

Then there is certification and part p to be considered 

Sorry if this isn't what you want to hear.

As for costings, if you are trying to budget if you allow a grand then plug this into your figures and you'll probably get some change

 

[Doc Hudson]

Guidance for any type of alteration, is to first verify the condition of the supply and existing equipment, that will be affected by additional electrical loads put on the installation. (often ignored on DIY lash-ups). As you are looking at adding significant loads that can't just plug into a 13A socket it is even more vital to have a proper initial assessment of your supply and earthing arrangements.  Even with all the wonders of the internet and mobile phone apps, this is a task that can only be done physically standing on site, seeing what is actually there and then connecting a test meter to appropriate cables. Plus saunas and steam rooms are classed as special locations, which are areas with some additional location specific regulations due to increased dangers of electricity usage in that environment. So you really do need someone to visit and do a site assessment. If you get any calculations or assumptions wrong, you could endanger your property and/or family.  The following extract from BS7671 wiring regulations puts this into context and is your starting point IMHO.  

     

Doc H.

 

[ErnieH]

TBH none of can really comment without really looking at the actual installation etc

So continually looking at forums won't give you a clear idea

Then there is certification and part p to be considered 

Sorry if this isn't what you want to hear.

As for costings, if you are trying to budget if you allow a grand then plug this into your figures and you'll probably get some change

Thanks for commenting Murdoch. When you say budget £1k would this include if we need to have our supply upgraded or do you just mean for the associated works for connecting all this up and testing/checking? I was expecting it to cost mega bucks if we needed the supply to the house upgraded. 
 

I guess when you mention certification and Part P, you are referring to the installer not being satisfied with the installation as it currently stands and therefore needing to do other works before being happy to certify?

Would a 35 y/o house require a rewire potentially?

 

[Murdoch]

Thanks for commenting Murdoch. When you say budget £1k would this include if we need to have our supply upgraded or do you just mean for the associated works for connecting all this up and testing/checking? I was expecting it to cost mega bucks if we needed the supply to the house upgraded. 
 

I guess when you mention certification and Part P, you are referring to the installer not being satisfied with the installation as it currently stands and therefore needing to do other works before being happy to certify?

Would a 35 y/o house require a rewire potentially?

Sorry I. Should have said for the work's downstream of the meter. 

If you think you can cut corners and do it your self and get it signed off later you may find this tricky as most of us won't do this

Supply upgrades are down to the dno and can be extremely expensive

 

[ErnieH]

Guidance for any type of alteration, is to first verify the condition of the supply and existing equipment, that will be affected by additional electrical loads put on the installation. (often ignored on DIY lash-ups). As you are looking at adding significant loads that can't just plug into a 13A socket it is even more vital to have a proper initial assessment of your supply and earthing arrangements.  Even with all the wonders of the internet and mobile phone apps, this is a task that can only be done physically standing on site, seeing what is actually there and then connecting a test meter to appropriate cables. Plus saunas and steam rooms are classed as special locations, which are areas with some additional location specific regulations due to increased dangers of electricity usage in that environment. So you really do need someone to visit and do a site assessment. If you get any calculations or assumptions wrong, you could endanger your property and/or family.  The following extract from BS7671 wiring regulations puts this into context and is your starting point IMHO.  

View attachment 10443      

Doc H.

Thank you, Doc. It does sound like I’ll have to get someone out before I can continue to plan, I just didn’t want to waste anyone’s time in the early stages but it sounds like I’ll have to pay for this advice as it’ll include testing so I suppose it won’t waste anyone’s time.

Just so I can keep my dreams alive, could I expect a 35 y/o installation to likely be Ok for a 7.8kw heater assuming that the installation was carried out correctly at the time and I’m prepared to lose an 8.5kw shower? Obviously assuming that there haven’t been any botched DIY things done in the house. I can forgo the steam room altogether if necessary but really want the sauna! Both if possible but it’ll be what it’ll be. 
 

Thanks again, I was expecting there to be a simple answer to this like, definitely not or that it will likely be possible but may need a new CU or something - I was clearly wrong but appreciate that being pointed out. 

 

[ErnieH]

Sorry I. Should have said for the work's downstream of the meter. 

If you think you can cut corners and do it your self and get it signed off later you may find this tricky as most of us won't do this

Supply upgrades are down to the dno and can be extremely expensive

Thanks Murdoch. I had a feeling that the outside supply change would be very expensive, probably too expensive. Would you envisage that being necessary or is it impossible to tell?

I’m not interested in cutting corners, at the end of the day I plan to sell my house on at a later date so I need these works certified and I don’t imagine any electrician will certify work that they didn’t do with cables that they can’t see. Supposing that it is feasible with the supply coming in, would an electrician certify just this part of the work or do you have to bring everything in the house up to current standards?

Thanks mate, even though slightly disappointing so far, the replied are very much appreciated. 

 

[Murdoch]

^^ impossible to say over the internet ..

 

[Doc Hudson]

Thank you, Doc. It does sound like I’ll have to get someone out before I can continue to plan, I just didn’t want to waste anyone’s time in the early stages but it sounds like I’ll have to pay for this advice as it’ll include testing so I suppose it won’t waste anyone’s time.

Just so I can keep my dreams alive, could I expect a 35 y/o installation to likely be Ok for a 7.8kw heater assuming that the installation was carried out correctly at the time and I’m prepared to lose an 8.5kw shower? Obviously assuming that there haven’t been any botched DIY things done in the house. I can forgo the steam room altogether if necessary but really want the sauna! Both if possible but it’ll be what it’ll be. 
 

Thanks again, I was expecting there to be a simple answer to this like, definitely not or that it will likely be possible but may need a new CU or something - I was clearly wrong but appreciate that being pointed out. 

There is no simple answer, as there are to many unknown quantities that can only be confirmed by seeing the installation.  As with anything in life if you do not have the skill or expertise to do it yourself you have to call upon the services of someone more knowledgeable. At the end of the day anything is possible at a price, but it may not always be economically viable. Assuming anything normally leads to complications, the only fail safe assumptions to make are; "Assume everything is faulty and sub-standard until you have proved it otherwise". (Which is the concept of the regulation in my earlier post). So before getting into the realms of what you want to do, the first question is "What parts of the installation have so far been proved to be satisfactory for continual use and/or compliant with current wiring regulations". If none, then any suggestions or proposals around what can or can't be done is pure guesswork and speculation.

Depending upon which part of the UK you are in, any new circuits will require Part-P building regulations compliance as well as the standard electrical installation certificate, which means you need someone to sign their name on the documentation accepting legal responsibility that the design and installation is compliant and safe. So you need to contact two or three local electricians to see if they are willing to come and provide an estimate/quote for the alterations you want.  It's no good anyone on the internet saying, oh yes you can do that, and it will only be £750, when they are not the ones who need to put their signature accepting legal liability!.

Your question is like expecting a simple answer to; I am looking to buy a 5year old van to carry work gear, how much do you think I should pay and what do you think the first two years servicing/repairs and running costs would be? I have seen a Ford, Vauxhall, Fiat & Citroen on the internet, which one will be the best?  Without seeing the vehicles, checking service history, maybe a test drive or AA/RAC inspection, no one could give any real answers over the internet.

Doc H.

 

[ErnieH]

There is no simple answer, as there are to many unknown quantities that can only be confirmed by seeing the installation.  As with anything in life if you do not have the skill or expertise to do it yourself you have to call upon the services of someone more knowledgeable. At the end of the day anything is possible at a price, but it may not always be economically viable. Assuming anything normally leads to complications, the only fail safe assumptions to make are; "Assume everything is faulty and sub-standard until you have proved it otherwise". (Which is the concept of the regulation in my earlier post). So before getting into the realms of what you want to do, the first question is "What parts of the installation have so far been proved to be satisfactory for continual use and/or compliant with current wiring regulations". If none, then any suggestions or proposals around what can or can't be done is pure guesswork and speculation.

Depending upon which part of the UK you are in, any new circuits will require Part-P building regulations compliance as well as the standard electrical installation certificate, which means you need someone to sign their name on the documentation accepting legal responsibility that the design and installation is compliant and safe. So you need to contact two or three local electricians to see if they are willing to come and provide an estimate/quote for the alterations you want.  It's no good anyone on the internet saying, oh yes you can do that, and it will only be £750, when they are not the ones who need to put their signature accepting legal liability!.

Your question is like expecting a simple answer to; I am looking to buy a 5year old van to carry work gear, how much do you think I should pay and what do you think the first two years servicing/repairs and running costs would be? I have seen a Ford, Vauxhall, Fiat & Citroen on the internet, which one will be the best?  Without seeing the vehicles, checking service history, maybe a test drive or AA/RAC inspection, no one could give any real answers over the internet.

Doc H.

Thanks again, Doc. I think my question was more general in the sense of would I be able to add 14Kw worth of appliances to a standard domestic installation. 14Kw seemed a lot to me so I just thought that I may get a, ‘you’re going to probably have trouble accommodating that’ or ‘that shouldn’t be a problem IF everything is Ok’. I get that isn’t the way this has gone though. 
 

As 10.5kw showers are quite common, I was hopeful to hear news that it would probably be OK but obv need to get everything checked and done correctly. I was wrong. Thank you for your help though, I’ll give the guy who does the periodicals on my warehouse a call and see if he’ll come and take look. 

By the way, I can’t seem to upvote those who’ve offered help, I assume maybe because I’ve only just registered on here. Sorry, would love to do that. 

 

[Doc Hudson]

 a standard domestic installation. 

This I think is your fundamental concept stumbling block,  as there is no such thing as a standard domestic installation. So no one can answer any more accurately than;  How long will a standard pair of shoes last? How much does a standard holiday cost? How much food does a standard family consume? How expensive is redecorating a standard house? What qualifications do I need for a standard job?  Even the two halves of a semi-detached property can have different electrical requirements. 

Doc H.  

 

[ErnieH]

This I think is your fundamental concept stumbling block,  as there is no such thing as a standard domestic installation. So no one can answer any more accurately than;  How long will a standard pair of shoes last? How much does a standard holiday cost? How much food does a standard family consume? How expensive is redecorating a standard house? What qualifications do I need for a standard job?  Even the two halves of a semi-detached property can have different electrical requirements. 

Doc H.  

Fair comment but would you ‘expect’ to be able to fit an electric shower in most houses for example (subject to checks)? I guess I was more getting at the supply coming in as anything else can be taken care of and is therefore possible. If the incoming supply is insufficient though then the whole idea needs to go in the bin if it’s as expensive as Murdoch above alludes to. 
 

I guess I could ask in a different manner, IF the incoming was 100amp and I was prepared to pay for a complete rewire from the meter onwards, would you then expect me to be able to get these things fitted or are we in the realms of calculating all appliances being used in the house? 
 

 

[ErnieH]

I may have answered my own question here to an extent. I’ve just got home and opened the white meter box outside and the fuse cartridge that’s security sealed says 60amp (see photo). This would seem pretty conclusive to me that the supply is only 60amp here, am I correct to think that this would rule out the sauna and steam room combination that draws 14kw? If so, would it rule out the 7.8kw sauna or is it still worth me having someone around to see if we can get that working?

Thanks again.



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