Secondary Consumer Units and Connectivity

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Before anyone says anything, I am not going to attempt to do any of this work myself. The basis for this post is to understand the process and materials required, so that when I can find a decent qualified electrician, I know what is going on, and how much I should be looking at, even though technically I don't understand it!

I have a fully populated 10 way Wylex Consumer unit in the main house and an 8 way Wylex Consumer unit in a treatment room, 40 metres away from the main house, that is currently under construction. The treatment room has an en suite bathroom, with electric shower, and a number of internal and external mains/lighting.

At some stage I will need to upgrade the main consumer unit to accomodate the work that needs to be done in the kitchen and a new conservatory.

After investigating, it seems that there are two options available to me to connect it all up:

Option 1. Fit a new larger consumer unit where an 80amp feed can be connected from the main consumer unit up to a secondary consumer unit in the treatment room.

Option 2. Fit a Henley block and power both CU's this way. The question of earth seems a bit unclear to me. Where is the earth taken from?

Whatever the situation, I will need to fit a mains isolation switch, to the main incoming feed, but will I need to do the same in the secondary area?

I realise that will be regs involved and I will also need to contact the electricity company so that they can do their bit, in turning the power off for the fitting of the Henley and Mains isolation unit.

Can anyone advise the best course of action, and what I should be expecting to pay for this type of work? All cable runs have been carried out, it's just connection and testing to completion, but it will need to be carried out in phases. I need to get the main house done first, and then move on to the treatment room as soon as it ready, which will not be for a couple of months yet.

Thanks in advance.
 
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There are too many parameters that need taking into account for an answer to be given on here. Get some prices from various electricians and if they are all in the same ball park then away you go !
 
Thanks for responding.

I am in the process of doing this. I did get one guy out, who quoted to put in a Henley, 2 mains isolation units, connection and testing to the secondary CU, for £520.00.

It seemed very high, for what is a days work, hence the reasoning behind understanding the process involved.
 
Option 1. Fit a new larger consumer unit where an 80amp feed can be connected from the main consumer unit up to a secondary consumer unit in the treatment room.
Assuming your electrician uses a CU which can have an 80A MCB fitted.

And that he decides that's a sensible design.


Option 2. Fit a Henley block and power both CU's this way. The question of earth seems a bit unclear to me.
Doesn't really matter, as long as it's clear to the electrician.

That it's not clear to you, and that you think that the issues are different between those two options, is because you aren't competent to do electrical design work.


Whatever the situation, I will need to fit a mains isolation switch, to the main incoming feed,
You will? Why?


but will I need to do the same in the secondary area?
I don't really understand why you need to do any of the work.


I realise that will be regs involved and I will also need to contact the electricity company so that they can do their bit, in turning the power off for the fitting of the Henley and Mains isolation unit.
No - your electrician will do that.


Can anyone advise the best course of action
The one you decided not to take before going ahead.


All cable runs have been carried out,
By whom?

Who will sign these declarations?:

I being the person responsible for the Design of the electrical installation (as indicated by my signature below), particulars of which are described above, having exercised reasonable skill and care when carrying out the Design, hereby CERTIFY that the said work for which I have been responsible is to the best of my knowledge and belief in accordance with BS 7671:2008, amended to 2011 except for the departures, if any, detailed as follows.

I being the person responsible for the Construction of the electrical installation (as indicated by my signature below), particulars of which are described above, having exercised reasonable skill and care when carrying out the Construction, hereby CERTIFY that the said work for which I have been responsible is to the best of my knowledge and belief in accordance with BS 7671:2008, amended to 2011 except for the departures, if any, detailed as follows.


These are not rhetorical questions - they are VERY important, because....

it's just connection and testing to completion
It doesn't work like that.

When you applied for Building Regulations approval for the extension, what did you say, or allow to be said on your behalf, or by any sort of omission tacitly accept, would be the way that you would ensure that the electrical work would comply with Part P?

That is also very important, because if it differs from what you actually do expect to have major problems in getting a completion certificate, and therefore being able to open your treatment room.

Have you considered your responsibilities under the EAWR? Your position regarding employer liability, public liability, the terms and conditions of insurances for those?
 
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Option 1. Fit a new larger consumer unit where an 80amp feed can be connected from the main consumer unit up to a secondary consumer unit in the treatment room.
Assuming your electrician uses a CU which can have an 80A MCB fitted.

And that he decides that's a sensible design.

Thank you. I will explore this when electricians come and quote.


Option 2. Fit a Henley block and power both CU's this way. The question of earth seems a bit unclear to me.
Doesn't really matter, as long as it's clear to the electrician.

Yes it does to me. I would like to understand the installation process, even though I am not qualified to carry out any of the work.

That it's not clear to you, and that you think that the issues are different between those two options, is because you aren't competent to do electrical design work.

Which is the reason for the post. I know that I am not competent to design the work required. I am simply posting to guage an idea as to what works and options are available to a qualified electrician when the work is done.


Whatever the situation, I will need to fit a mains isolation switch, to the main incoming feed,
You will? Why?

Because I want to be able to turn off the supply to my house without having to call upon the energy supplier to do this for me. I have future works to be carried out and dont see the need to pay additional money should it be required.

but will I need to do the same in the secondary area?
I don't really understand why you need to do any of the work.

Please excuse the phrase "I" and "Electrician". Maybe I should have phrased this differently.

I realise that will be regs involved and I will also need to contact the electricity company so that they can do their bit, in turning the power off for the fitting of the Henley and Mains isolation unit.
No - your electrician will do that.

I have already contacted the energy company to arrange for them to come and turn the power off, which will take place in November.

Can anyone advise the best course of action
The one you decided not to take before going ahead.

Excuse me for asking a valid question.


All cable runs have been carried out,
By whom?

The 1st fix electrics were carried out by qualified electricians, according to a design that they supplied me with and the electrician that recently came agreed with. They have qualified their part of the installation. The second fix will take care of testing and connectivity. So the assumption is that the electrician who will connect everything up and test the installation will certify the complete installation.

Who will sign these declarations?:

I being the person responsible for the Design of the electrical installation (as indicated by my signature below), particulars of which are described above, having exercised reasonable skill and care when carrying out the Design, hereby CERTIFY that the said work for which I have been responsible is to the best of my knowledge and belief in accordance with BS 7671:2008, amended to 2011 except for the departures, if any, detailed as follows.

I being the person responsible for the Construction of the electrical installation (as indicated by my signature below), particulars of which are described above, having exercised reasonable skill and care when carrying out the Construction, hereby CERTIFY that the said work for which I have been responsible is to the best of my knowledge and belief in accordance with BS 7671:2008, amended to 2011 except for the departures, if any, detailed as follows.


These are not rhetorical questions - they are VERY important, because....

it's just connection and testing to completion
It doesn't work like that.

When you applied for Building Regulations approval for the extension, what did you say, or allow to be said on your behalf, or by any sort of omission tacitly accept, would be the way that you would ensure that the electrical work would comply with Part P?

That is also very important, because if it differs from what you actually do expect to have major problems in getting a completion certificate, and therefore being able to open your treatment room.

The building is too small to fall under the requirements of building regs, BUT, buidling regs have been obtained for the mains drainage installed, and will be obtained for the electrical works carried out.

Have you considered your responsibilities under the EAWR? Your position regarding employer liability, public liability, the terms and conditions of insurances for those?

Yes I have, hence the need to ensure that the electrical works comply with all regulations required to ensure a safe working environment for my wife and her clients.

With all due respect, I came on to the forum to seek advice, so that I could understand the works that are required. I have no intention of carrying out any of the works, but as a project manager to the audio visual industry, it is my nature to try to understand the processes involved in any installation. The better the understanding the better the planning, and the better the idea of budget costs involved.
 
With all due respect, I came on to the forum to seek advice, so that I could understand the works that are required. I have no intention of carrying out any of the works, but as a project manager to the audio visual industry, it is my nature to try to understand the processes involved in any installation. The better the understanding the better the planning, and the better the idea of budget costs involved.
Try not to worry too much about to BAS. He sometimes jumps to (not necessarily correct) conclusions which correspond to how he would like things to be in order to enable him to launch into his 'forum-policing' mode.

To be a little fair to him, we see many cases in which it is fairly obvious that "I just want to understand.." (or "my electrician is on holiday, so I'd like to ask a few things...") questions actually come from (clearly inadequately competent) people who actually intend to do the work themselves and not involve any electricians (and maybe to 'break the law' by not complying with requirements of Building Controls) - but that clearly does not excuse anyone for assuming that such is the case without some fairly convincing evidence.

Kind Regards, John
 
I see you are still either unable or deliberately unwilling to read only what I write.

And BTW - IHNI what the OP wrote above - if he cannot be bothered to format his posts to make them readable, I sure as hell am not prepared to struggle with them.
 
John,

Many thanks for your reply. I have seen BAS's posts and was expecting a similarly phrased response from him.

I appreciate that there are all kinds of ridiculous and questionable posts from people that have no business wiring a plug let alone a consumer unit, and that by advising and helping, could promote unlicensed and potentially life threatening environments. Everyone has a duty of care, in that where possible the safest advice should be meted out.

Having said that, I did qualify my post initially by pointing out that I will not be attempting any of this work myself. All I am seeking is advice, and the best possible way forward in understanding what work needs to be carried out. I'm doing this so that I don't get poor workmanship, or pay more than what the job is worth. There are a lot of dodgy 'qualified' electricians out there these days, and choosing the right one is not an easy task.

BAS did at least answer one my questions, so thank you for that.
 
I see you are still either unable or deliberately unwilling to read only what I write.

And BTW - IHNI what the OP wrote above - if he cannot be bothered to format his posts to make them readable, I sure as hell am not prepared to struggle with them.

I am not unwilling, and I am certainly able, but please see the first paragraph of my post. It's advice I am seeking not a lesson.

Also, there is absolutely no need for this sort of rhetoric behaviour. I am new to the forum, and did try to put my quotes and your quotes into some sort of legible format, but the bold, italics, and colour fonts do not seem to be working.
 
I appreciate that there are all kinds of ridiculous and questionable posts from people that have no business wiring a plug let alone a consumer unit, ... Having said that, I did qualify my post initially by pointing out that I will not be attempting any of this work myself.
Indeed. However, although I'm not defending BAS, you will understand that "they always say that" - so the fact that someone says that they will not be undertaking the work themselves does not, per se, really help us to know the truth in any particular situation!

Also, as you are probably aware, BAS tends to write 'in code' sometimes - as regards your Option 1, I think it unlikley that any electrician would consider that design, even if (s)he could find an 80A MCB and a CU into which it would fit. I think, but cannot be certain, that such is what he was trying to imply.

Kind Regards, John
 
John,

I do understand the predicament, that you guys are in, and I do sympathise. I've seen the ramifications first hand to unsafe working practices, and negligent/substandard wiring. On many ocassions, I have walked my guys off site when the environment is not safe.

With my situation, I know that there will be alot more involved, that I have not posted, such as earthing upgrades where required, and other pieces, that I would expect a qualified electrician to do, and charge me for.

Anyway. Happy trails.
 
As ricicle stated earlier there are too many (unknown) parameters to make a informed decision about whether your proposals are achievable.
You mentioned that the DNO will need to come out and isolate the power while Henleys etc are fitted - that may well be the case unless you already have an isolator fitted.
But more importantly a proper assessment will need to be made of the total load on your installation both by the electrician completing the installation and the DNO concerning their main fuse.
For example you are supposed to notify the DNO if you fit a second electric shower or add another appliance that draws a significant amount of power.
You also don't mention the position regarding RCD protection which will be required certainly in your new build and probably when you replace your 10 way.
Then there is the question of the earthing arrangement in so much as what you have now and what the DNO will allow.
 
Hello,

Option 2 would be my choice.
I would install a switch fuse at the intake position in the main building to supply yoy treatment rooms rated at 63a. If you should wish to sub meter at a later stage it's easily done. The retain the existing consumer unit in the house. The main isolator will of course, control both buildings.

The earthing arrangement will be determined by your electrical engineer.

Regards,

NA
 
Riveralt.

Perfect response. Many thanks.

There isnt an isolator fitted at present.

When the plan was drawn up, and the 1st fix took place, the electricians, did indeed carry out a load assessment. They did leave a copy of it, and I will have to locate it to make the second fix electricians life much easier.

The treatment room bathroom is the only place that has an electric shower. I seem to remember that they talked about replacing the CU in the main house for something lot more substantial and then putting in place an 80A MCB to feed the the secondary CU, which I am assuming will contain its own RCD's. I am not too sure now. My reason for asking about this option, was that it seemed to be the easiest way to supply power, but...it may be too much load on a 100A CU, when things are in operation, hence option 2.

With regards to earthing. I am fairly sure that there is already adequate earthing in the main house, and that along with the cable from the house the treatment room that there is also an earth cable installed.

Given all these variances, it may be an idea to talk to a few more electricians and guage opinions when they can see the tasks in front of them.
 

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