14 new 9.5kw showers to be installed on existing supply

[ruston]

So ok all that's been said , people's opinions , what would you do? , would you do the job or would you say get a plumber in

I would just like to know what the DNO would have to say about it .

 

[davethsparky]

"here's your bill for the new supply, thankyou very much"

 

[ruston]

"here's your bill for the new supply, thankyou very much"

Sticks in my mind that you have to notify them of load increases over a certain level, although I can't remember what it is lol.

 

[davethsparky]

Yes but with the load after diversity being more than the existing incoming supply (100A TP) without even considering the existing load I kind of assumed that conversation would be happening anyway.

 

[ruston]

Yes but with the load after diversity being more than the existing incoming supply (100A TP) without even considering the existing load I kind of assumed that conversation would be happening anyway.

Fair enough , I confess to not reading the whole thread ,it was just something niggling in my mind that you had to notify them of additions over a certain level.

 

[Gavin A]

surely this is a none starter from both electrical and plumbing standpoints, at least without some form of pressure buffer (I forget the name of it) on the incoming water supply and an upgrade to a 200amp per phase supply or so.

I guess it could be something that you might get away with in practice as the loads will mostly only be applied for 10-15 minutes at a time, but it seems like a really silly idea from multiple viewpoints, at least unless there's a really good plumber involved to ensure the fluctuations in water pressure as different showers turn on / off aren't going to impact on the other showers. If there were a decent plumber though, they'd surely be advising in favour of a tanked solution anyway, probably with a pumped hot water ring to get rapid hot water from the showers.

 

[sparky351355]

Ok i'll play the game here.

Assuming they are split as equally as possible (5,5,4) and as you used 230V in your earlier calculation i'll assume they are rated 9.5KW at 230V.

Total connected load on L1 = 5 * 9.5KW = 47.5kW = 197.9A

Allowable diversity if you consider thsi to be a boarding house = 100% FLC of largest 2 appliances + 25% FLC of all other appliances
Current for 1 * 9.5KW unit = 39.6A
Load after diversity = (2*39.6)+(3*(39.6/4)) = 79.2 + 29.7 = 108.9A

However you could consider these to be individual dwellings in a block then you take 100% FLC of the shower in each dwelling so we get back to 197.9A.

Either way that's going to be a bit much for your existing 100A supply

I'm upgrading the mains to 125 a on this one

 

[sparky351355]

you can not applly dievesirty to intantaious water heaters

Yes you can dave OSG

 

[Guitarist]

So nobody is going to come up with a load per phase then !

With the greatest respect, this is YOUR job, not ours. We have given our opinions, but you will be the one getting paid. All the best, whatever you decide.

 

[telectrix]

provided that the use of the showers is staggered, you might just manage with a 125A/phase supply, but can the roof support a 300 gallon tank of water?

 

[sparky351355]

I know this and thanks for the comments , regardless of the permutations here one more thing:-

Diversity applied per phase or per total load?

 

[sparky351355]

I get it to 68a per phase at total load ,
113 a per phase

 

[sparky351355]

These are NOT single dwellings by the way

 

[Richard Burns]

If you have calculated at 113A per phase from the electric showers, with diversity applied, and you already have 35A per phase from existing loads with (practical) diversity applied, this equates to 148A per phase and you are suggesting a 125A supply?

Do also consider if this is sheltered accommodation, are residents likely to be awoken at the same time and theretofore all use the showers within the same time frame?

 

[D Skelton]

With a couple of timer switches and a few TP relays you could quite easily fit a shower supply system in a central location that would force staggered use, say three showers (could be more? Up to you..), one on each phase for 30 mins, then the next three showers, then the next three and so on... No leccy supply issues, no water pressure issues, and all that will have changed is that residents will have to conform to a specific time regime for showering otherwise they will miss their slot and have to wait an hour or two (depending on how many showers you allow to run at any one time) till the next time slot for showering.

Problem solved!