Diversity and Showers

[andyelectric]

Hi, please be kind to this Electrical Trainee fresh out of the forces. This is my first question on the forum. One thing that was not discussed in depth on my course was diversity, and reading up there seems a fair bit of subjectivity and difference of opinions on it.

Now that I have my shiny new quals the missus has requested I fit a 2nd electric shower. We currently have a 10kw fitted, and she'd like the same again. Flat has gas heating and cooker, so other loads would be normal household appliances. Both showers would be used as we have a lodger, but would in all reality rarely be used at the same time. Worst case would be both on at the same time for 10m whilst the kettle and washing machine etc were on.

My current supply is as follows. 100A from cut-out(I saw the fuse go in). 80A switch fuse supplying submain run in 16mm swa. Another metal 60A switchfuse then into CU. (Reason for 2nd SF is that it was there already and used as a handy termination for the swa when meters were moved).

My feeling is that I'll be ok with the 60A. I could quite easily change the 2nd SF for a metal adaptable box and henley though, thereby uprating my supply to 80A.

Would you guys on here recommend removing the 60A SF.

 

[Farmelectrics]

install your shower highly unlikely to be using everthing at once have a good read of the on site guide theres a chapter or a page about diversity in there diversity is sometimes left to the installer to work out using your past experiences

 

[Octopus]

I think you should consider a "pumped" shower and use the hot water from your tank!

 

[Marvo]

I've removed several off-topic posts. Please either stay on topic or stay off the thread entirely. Thank you.

 

[shanky887614]

I think you should consider a "pumped" shower and use the hot water from your tank!

a pumped shower has higher water pressure and is nicer to use.

if you want a 10kw electric shower then at 40amps it should be ok depending on installation method etc.

i would suggest swapping the 60amp isolator for something bigger, it shouldnt be a problem because i doubt it will get warm unless it is used for a long time.

 

[andyelectric]

Thank you Marvo for cleaning up the thread.

Murdoch, unfortunately my combi-boiler although perfectly suited to my hot water and heating needs cannot support a shower and I do not have a hot water tank from which to run a thermostatic shower.

From research it would seem that diversity is a pretty subjective subject. The OSG seems to me pretty prescriptive, but on google I have found some pretty common srnse arguments backed up with reasoning that 60 amps may be ok for 2 high power electric showers.

However I obviously have no experiemce in this area. So I have 3 choices.

1. Fit the 2nd shower on 60 amp supply.
2. Fit with 2nd S/F removed on 80 amp supply (my present favourite).
3. Do not fit 2nd shower.

Each of these 3 options is dependent on diversity, and I was hoping to pick up on reasoned (reasoned being the operative) arguments on the best way to proceed.

Cheers Andy.

Apologies for typos, on phone.

 

[ruston]

Forget the electric shower, treat your family and run it as others have said from the gas, no one will use the other electric one after they have used the higher power gas powered one.

Sorry I must have cross posted with you.

 

[andyelectric]

Just thought I'd add. I'm fine with choosing cable, mcb etc, and fitting shower, just I have no experience on the weakening of fuses which is what I am most worried about. (ie I don't want to blow my 60amp fuse 2 years down the line and be in stook if I could have simply upgraded to 80 amp.)

 

[davesparks]

Is the submain relying on the 60A fuse or is it suitably sized (bearing in mind route, VD and max Zs) for 80A?

 

[andyelectric]

Meaured Ze at the board is 0.31 ohms, and the run to each 2 showers are under the ground floor joists(so pretty cool for cable). No problem with cable runs as both pretty short runs compared to an up round the loft and down type.

The submain relies on an 80 amp switchfuse, DNO fuse at cutout is 100A, the only reason the 60 amp is there is that it was remaining in the cellar from a meter move. The 60A SF could be reasonably easy enough be removed thereby upgrading supply to 80A.

 

[davesparks]

Ok so your Ze is ok, but what is the Zs of the submain/Zdb of the board?

The submain is currently operating on the 60A fuse for overcurrent protection whilst the 80A will be providing fault protection.
The way you describe the situation this was not intentional, but that is the way it will operate anyway.

Are you sure the 60A fuse wasn't replaced with a solid link at the time the work was done ?

 

[benji]

isn,t there types of switches that prevent two showers being run at the same time ??

 

[davesparks]

isn,t there types of switches that prevent two showers being run at the same time ??

There are, but there is no need for such fancy nonsense in this case.

2x electric showers + normal domestic loading won't bother an 80A fuse for a good few hours.
Probably won't bother a 60A fuse for quite a while either but then it will probably become 'tired' after a while

 

[Lucien Nunes]

Concur, it will work but the 60A fuse will be stressed from time to time, while the 80A probably won't. Rip out the SF and carry on.

 

[Marvo]

Does he need RCD protection?

 

[davesparks]

Does he need RCD protection?

Yes, but as a fully qualified 5 week danger he presumably knows this already.

 

[Marvo]

As a qualified African I thought he might but wasn't 100% certain

 

[andyelectric]

Ok so your Ze is ok, but what is the Zs of the submain/Zdb of the board?

The submain is currently operating on the 60A fuse for overcurrent protection whilst the 80A will be providing fault protection.
The way you describe the situation this was not intentional, but that is the way it will operate anyway.

Are you sure the 60A fuse wasn't replaced with a solid link at the time the work was done ?

Dave, the 60A is as a have said. It is an mem jobbie from 40 years ago. Pulled the fuse last week and changed the cu. ji

 

[davesparks]

Dave, the 60A is as a have said. It is an mem jobbie from 40 years ago. Pulled the fuse last week and changed the cu. ji

Ok so it's not been replaced with a link then, why didn't you gland the SWA directly onto the CU when you replaced it? Far better than having the unnecessary switchfuse left in place!

And how about that Zs on the submain?

 

[telectrix]

fit shower, dump the 60A fuse. 80A fuse will stand a 50% overload for longer than a shower runs ( assuming no teenage daughters. that could be fun when shower goes freezing cold when they stay in it for yonks).

 

[EastAnglian]

No need for the 60A fuse, take it out of the equation. 2 off 100A connector blocks (much nicer to work with than a Henley block), keep the double insulation inside the JBs, no need to box them. Job done.

 

[davesparks]

No need for the 60A fuse, take it out of the equation. 2 off 100A connector blocks (much nicer to work with than a Henley block), keep the double insulation inside the JBs, no need to box them. Job done.

So you have checked the cable calcs and the Zs etc then have you?

And what do you mean by 100A connector blocks? I've not seen them before but they sound dodgy! How exactly do you terminate SWA into them without the need for an enclosure?

 

[EastAnglian]

And what do you mean by 100A connector blocks? I've not seen them before but they sound dodgy! How exactly do you terminate SWA into them without the need for an enclosure?

Cable calcs have been dealt with by earlier posters, no need to repeat.

Thanks for reminding me the incoming cable is SWA, which of course needs correct termination.

A link to those dodgy connector blocks (but not my supplier!):

100A Single Pole Tails Connector Box - Single Pole

 

[davesparks]

Cable calcs have been dealt with by earlier posters, no need to repeat.

Thanks for reminding me the incoming cable is SWA, which of course needs correct termination.

A link to those dodgy connector blocks (but not my supplier!):

100A Single Pole Tails Connector Box - Single Pole

They are single pole Henley blocks, you said they were a better alternative to Henley blocks !

Cable calcs haven't been dealt with, there have been no details as to any apical rating factors yet.

 

[EastAnglian]

They are single pole Henley blocks, you said they were a better alternative to Henley blocks !
.

Since they are made by Click I don't really suppose they are Henley blocks at all!

Horses & courses, but I find it easier to fit 25mm tails into these than the double decker ones, especially if there are already existing tails terminated.

Cable Calcs - too much wine, I don't do calcs after drinking ;-)

 

[davesparks]

'Henley block' is a common term for what would be better described as a 'service connector block' also known as Lucy, ESCO or mains blocks.
All available in single or double pole versions

 

[EastAnglian]

Just as there are many vacuum cleaners but only one Hoover, there's only one true Henley :conehead:

Insulated Connectors Boxes | WT Henley

 

[davesparks]

But by the same token we all know what is meant when someone says Hoover, Henley block, megger, spanset, bulb etc
They have become common names for a type of product.

 

[andyelectric]

isn,t there types of switches that prevent two showers being run at the same time ??

Does he need RCD protection?

Hi Marvo, submain from 80a SF to 60A SF is run in swa in cable tray in cellar. From 60A to consumer unit is tails in open air. So no rcd required except fro CU to showers.

 

[andyelectric]

isn,t there types of switches that prevent two showers being run at the same time ??

There are, but there is no need for such fancy nonsense in this case.

2x electric showers + normal domestic loading won't bother an 80A fuse for a good few hours.
Probably won't bother a 60A fuse for quite a while either but then it will probably become 'tired' after a while

This is exactly the sort of answer I am after. 2 electric showers in a house is a common enough occurence(there were 2 in my last house , and I expect many of these setups are running on 60A fuses in the cutouts)

My feeling is that it is very unlikely that the 60 will ever blow. It will be a rare occurence for the 2 showers to be running at the same time. However being a newbie 'tired' fuses are not something I have come across.

However, as it will be relatively easy to remove the 60A from the equation I think I will do this and fit the second shower.


However,

 

[andyelectric]

isn,t there types of switches that prevent two showers being run at the same time ??

Ok so it's not been replaced with a link then, why didn't you gland the SWA directly onto the CU when you replaced it? Far better than having the unnecessary switchfuse left in place!

And how about that Zs on the submain?

3 flats supplies pass through my cellar and it was not possible for the swa to reach the new CU. Can't remember the Zs of the top of my head, but it was extremely close to the Ze of 0.31.

 

[EastAnglian]

3 flats supplies pass through my cellar

Now that's the way to do it .... run your electric showers off somebody else's supply

 

[Darkwood]

Andy as a self admitted 5week wonder I normally don't have the time for you and your fast track rip of courses hence you are here asking what would be a basic question BUT!!!! as you have served our country and possibly put yourself in a position that many on here could never imagine I'll find plenty of time for you...

Going slightly off tangent I would recommend you find a job as an Electricians mate for a few years, this will give you vital experience in our real world and give you a guide for all your questions and any corrections to your work.

My input on this thread is nothing more but only my hat off to you for doing a service while most of the benefit scroungers out there think life owes them a living :welcome:
Its clear from Marvo's input that you will have been slated and got a lot of negative comments but I put it to them to commit their own services to this country as you have!
Any future questions you have I'll be happy to help a man of your background!.... regardless of the Electrical Trainee status :icon12:

 

[andyelectric]

Andy as a self admitted 5week wonder I normally don't have the time for you and your fast track rip of courses hence you are here asking what would be a basic question BUT!!!! as you have served our country and possibly put yourself in a position that many on here could never imagine I'll find plenty of time for you...

Going slightly off tangent I would recommend you find a job as an Electricians mate for a few years, this will give you vital experience in our real world and give you a guide for all your questions and any corrections to your work.

My input on this thread is nothing more but only my hat off to you for doing a service while most of the benefit scroungers out there think life owes them a living :welcome:
Its clear from Marvo's input that you will have been slated and got a lot of negative comments but I put it to them to commit their own services to this country as you have!
Any future questions you have I'll be happy to help a man of your background!.... regardless of the Electrical Trainee status :icon12:

Cheers for the advice darkwood. But I have no intention of being an electricians mate at 42 years old. Having worked with electrical gear on ships for many years and having served an engineering apprenticeship I have a reasonsble electrical knowledge and although I am not experienced in this particular field, an average domestic setup is pretty basic, so I can't see there being much to trouble me. I am long enough in the tooth not to work on something I do not feel capable of and not comprimise myself.

 

[andyelectric]

Now that's the way to do it .... run your electric showers off somebody else's supply

I must admit......... But, my electric needs aren't that bad, I don't have a cannabis farm in the cellar just yet. Then again, the cut-out they didn't seal when moving the meters on which the meter man hasn't commented on twice.

JOKING

 

[Engineer54]

Cheers for the advice darkwood. But I have no intention of being an electricians mate at 42 years old. Having worked with electrical gear on ships for many years and having served an engineering apprenticeship I have a reasonsble electrical knowledge and although I am not experienced in this particular field, an average domestic setup is pretty basic, so I can't see there being much to trouble me. I am long enough in the tooth not to work on something I do not feel capable of and not comprimise myself.

And on that note, ...I rest my case!!

 

[andyelectric]

And on that note, ...I rest my case!!

Your case being??????

 

[Engineer54]

Your case being??????

That, ....it is the typical response of a electrical trainee. You've done your 5 weeks so don't need to work as a mate, and nothing much to domestic installations. In your own mind you're now fully qualified!! Right?? ...lol!!

 

[andyelectric]

That, ....it is the typical response of a electrical trainee. You've done your 5 weeks so don't need to work as a mate, and nothing much to domestic installations. In your own mind you're now fully qualified!! Right?? ...lol!!

I have worked as a Royal Navy engineer for the last 22 years, all hands on, and for the last 16 years as head of my own engineering section maintaining and fault finding on a variety of electrical systems.

Certainly the houses I have lived in have had quite simple electrical installations.

I feel qualified to work in most domestic situations. I am well aware that I will come up against situations that I have never before experienced, however my entire career has been filled with situations like that and research inevitably solves the problem.

Where research does not work, I will come on this forum and ask. If I do not feel competent to complete work after all this then I will not attempt it.


Unfortunately, there is not much call for Weapon Engineers in Portsmouth without the company inevitably taking pension monies into account when determining payscales, so I have decided to branch out and do something related but slightly different.

I'd appreciate it if you would stay off any threads I start in future unless it is to provide a reasoned answer to the original question. I believe your last (kindly deleted by Marvo) was "Are you mad" with no reasoning whatsoever.

Elevating oneself on an anonymous forum is an easy thing to do, perhaps you should step down off the pedestal you have created for yourself.

 

[Engineer54]

I have no need to elevate myself as you put it. I will comment on any thread as i see fit, as you or anyone else here can....

Not too sure how being an ex weapons engineer on a navy ship has any correlation with being a domestic electrician, but as you say, you feel qualified so you must be right!!

 

[HandySparks]

Not too sure how being an ex weapons engineer on a navy ship has any correlation with being a domestic electrician, but as you say, you feel qualified so you must be right!!

You have to admit though, E54, that weapons engineer is likely to be better preparation for being an electrician than if he were a shelf stacker or hairdresser?

BTW, I'm not saying that there isn't a lot to learn, even after becoming 'fully qualified' (whatever your definition of that is).

 

[Engineer54]

You have to admit though, E54, that weapons engineer is likely to be better preparation for being an electrician than if he were a shelf stacker or hairdresser?

Maybe, but then you can say the same about all these IT installers, and other vaguely associated professions/trades, it doesn't make them electricians domestic or otherwise does it.

 

[andyelectric]

Maybe, but then you can say the same about all these IT installers, and other vaguely associated professions/trades, it doesn't make them electricians domestic or otherwise does it.

And still waiting for a well reasoned answer to the original question.

I am happy for you to find me "mad" for what I proposed but please indicate why. This is where your experience would help, by providing examples and reasoned statements.

 

[Darkwood]

The way I see it Andy you are well experienced and knowledged in a select area of Electrical Engineering but will have little if any experience as a domestic Electrician qualified or not, Ive had many apprentices from many backgrounds and regardless of previous related or unrelated experiences they all had to learn the basics from scratch with onsite help, having said this you have an edge in understanding Electrics but what I don't understand is why housebashing, this has no relationship to the field you were in. You would be more suited to joining a company of Electrical Engineers and working alongside a seasoned Engineer in the Industrial sector until you ground your feet - better suited, better money, better prospects and key is a shortage in this sector but whatever way you turn you will need guidance onsite or you will find yourself in this situe on a regular basis.

Note - Its advice not a way to belittle what you already know but you also have to realise what you spent 20yrs doing may now be irrelevent as you chose a strange unrelated direction, yes you may be comfortable more than some in aspects of it but you still have a lot of regulations to learn and not just Electrical but Building reg's too and this is a steep hill if your climbing it alone.

Take it as constructive advice and not a personal attack which you seem to be doing.

 

[Andy78]

Just my two penn'th and speaking from my experience only.

My background as an electrician is having being "brought up" in commercial and light industrial installation. First a labourer, then a mate, then a fully qualified electrician. I had about a decade in experience in total when I went on my own as a self employed sole trader, however I had never worked in a domestic situation at all. I did not feel confident to go and start bashing about in customer's homes as it was simply an area I had zero experience in.
I had no qualms whatsoever in subbing to a mate of mine who had done domestic work all his career. I did this to shadow him to gain a bit of experience in domestic work so I could go into my own customer's houses knowing I could now provide the best job possible. I didn't feel belittled or daft and certainly learnt a heck of a lot in doing so.

 

[andyelectric]

Darkwood and Andy I may have not represented myself clearly. I wish to be semi-retired as I have pension and investments to back me up. This would not sit well with working for someone else. Nor would it sit with starting an engineering job. I see 'house bashing' as you call it as something to occupy me, and hopefully bring in a bit of extra cash from. And I like the idea of being my own boss, albeit this might not be an ideal route to take. The course I did was very short I admit, but it did not teach me anything new electrically. Obviously the wiring and building regs were new to me but pretty easy to get your head around. If something seems beyond me I will research, will not be attempting anything that I could be unsafe at.

 

[davesparks]

It's not just the electrical knowledge, there are various practical skills you need to have to be able to do a decent overall job.

 

[andyelectric]

It's not just the electrical knowledge, there are various practical skills you need to have to be able to do a decent overall job.

That is a very fair point Dave, and of course the area where experience counts for a lot. I am aware that this will probably be my biggest challenge. Maybe even to extent of having a practice in my own home prior to attempting something in a customers house if I have never completed it before. I do have a fair amount of hand-skill and have always been a competent DIYer so hopefully that will help a bit.

 

[Octopus]

That is a very fair point Dave, and of course the area where experience counts for a lot. I am aware that this will probably be my biggest challenge. Maybe even to extent of having a practice in my own home prior to attempting something in a customers house if I have never completed it before. I do have a fair amount of hand-skill and have always been a competent DIYer so hopefully that will help a bit.

Absolutely and the worst part is sorting out the mess of DIY dave!

 

[Engineer54]

And still waiting for a well reasoned answer to the original question.

I am happy for you to find me "mad" for what I proposed but please indicate why. This is where your experience would help, by providing examples and reasoned statements.

And here's your answer.... Why would you need two 10KW showers in a flat?? Why not two 8KW showers if you really need two?? As you already have a gas supply for heating, Why not invest in a system that CAN run showers and store hot water??

I have a 4.6 KW shower here (no gas, except bottled gas for cooking) and that unit gives more than enough hot water in the coldest of weathers (not uncommon for temperatures to drop to -10C here in winter)...
Never had nor wanted an electric shower in the UK ever, and certainly not a shower rated at anything near 10 KW!! So as a i said Madness!! ...lol!!