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I am remodeling a house and need to put in place a completely new electrical wiring along with security and surveillance systems (wiring for motion sensors and CCV cameras outside).

I am going to hire an engineer for the project. However I'd like to understand the typical requirements for such a project to be better prepared for my conversations with contractors.

My idea is to ask for a CAD project with a set of diagrams/views. Specifically, the following:

  • Blueprint with all the lights, sockets, switches, meter and distribution board placed on the floor plan.
  • Schema listing the cable types and maximum power allowed per circuit.
  • Distribution board plan.
  • Exact layout of cable on walls/ceilings including enclosures, where needed (2D/3D?).

Once the above is complete, I would expect the engineer to control the execution of the plan and test the wiring once it is installed.

Overall, I want to accomplish 2 things:

  1. Ease of maintenance for years to come.
  2. High quality electrical wiring to be built.

Questions I have:

  • Are there any important artifacts/documents I should be asking the engineer to provide?
  • Should I be asking an electrical engineer to also design the wiring for CCV cameras and motion sensors or is this job best left to someone else?
  • Perhaps I am over-engineering and the above list can be simplified?

UPDATE I am located in Europe and not concerned much with the local regulations as I am sure the requirements for regulators will be met at the end.

  • The location would help, the regulations do differ... – Solar Mike Aug 24 '19 at 19:15
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    If an engineer is required O.K. but you want what we call a 1 line drawing this shows the size of the wiring and devices used, I guess you could have it “blue printed” but that sounds like extra costs. In the U.S. (Oregon) I do complete layouts showing everything from the service, transformers panels and devices , with the arc fault calculations and load values. As far as serviceable or maintenance that goes back to the quality of the parts not so much the wire. Installing quality components down to terminal blocks instead of wire nuts for example is more of a quality and easy to repair later. – Ed Beal Aug 24 '19 at 21:34
  • @EdBeal perhaps an engineer would not required but I find it difficult to hire an electrician in my area who would be able to do even the 1-line drawing. One concern I have about 1-line drawing is that it does not show where exactly the wires are. So if 10 year later someone needs to attach a shelf to a wall there will be no way to know where the wires are. – Andrew Aug 24 '19 at 21:54
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I think you're over-engineering it.

Nobody really bothers specifying cable locations that precisely for electrical wiring. There are rules to protect electrical wires from damage, but they don't involve precise mechanical drawings of the build.

Further, you aren't going to be able to find anyone to install it to your diagram. Electrical engineers don't do house wiring, and electricians who do house wiring don't follow diagrams precisely like that, they just throw it in quick-and-dirty. Wiring is protected from damage, but using different techniques - for instance in North America there's a rule that you can go in 1-5/8" (40mm) without concern because wires and pipes are either guaranteed to be deeper than that, or will be guarded by a metal warning plate.

However, since you are aiming for top quality and easy maintainability, there is definitely something you should think about: Metal conduit. This is where you lay a type of pipe designed for electrical service (and some of it pipe-fits quite easily) and then you run the circuits in the pipe using individual wires (i.e. Not with multi-conductor cables). The piping does several things for you.

  • It physically protects the wiring from subsequent mechanical work, similar to metal guard plates.
  • Wiring grounds is often unnecessary - the pipe is it - so 30% of your wires just go away.
  • It allows easy wiring generally - conduit wire is much easier to work with.
  • It allows multiple circuits per conduit (to a limit) - allowing economy of conduit.
  • You can expand or customize it later.
  • If wire damage or splice failure occurs, does a good job of protecting you and preventing fire or shock - it nearly serves the function of American style AFCI breakers.
  • It is the highest quality installation you can get.

Generally, data cables are not allowed in mains electrical conduit or junction boxes, due to the risk of a wire melt putting mains voltage on equipment not rated for it. (Fiber-optic is OK). However you can lay parallel conduit for telecomm, and that conduit can be plastic.

Suffice it to say, designing a good conduit system is a very good outlet for the high standards you are setting.

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  • do you think it makes sense to use metal conduit everywhere in the house or would this be simply wasteful? I was thinking it would certainly make sense in places where replacing the wire will be difficult. – Andrew Aug 26 '19 at 10:13
  • @Andrew sure, you can do a blend of the two systems. – Harper - Reinstate Monica Aug 26 '19 at 16:43
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This ended up a bit long so bear with me. You can get whatever you want with enough $ Wires are easy to trace so I don’t see that as a problem. in an industrial building the prints don’t show the exact location. A basic riser diagram or a 1 line is it unless you have a lot of spare cash for a final “as built” and residential is less exact but the plans are within a few inches. I know some people want certain things and I did get several jobs in years past for 1 gentleman that specified all the 20 amp circuits to be run with #10 wire no 15 amp circuits at all even the door bell had its own circuit wired with #10. The next requirement was to have all the labeling located on the top or up on the cables. We got the job but to tell the truth I almost missed the label up requirement and thought the home owner would be difficult to work with, since I already ran the numbers for the quote at that point so I doubled it and submitted the quote. I got the job and he was very happy with my work.

about 7 years later he was building the perfect home fixing the things he did not like with the first, he contacted me and asked for a quote on the new building and said he understood prices had increased both for copper and labor and if I could do the new place for + 23% more I could have the job. He wanted the contract by the weekend it was almost identical to the first place, very minor changes in my opinion. I took the original contract with a 20% increase and got my first look at the plans, now the electronic switches we used had come down in price and the LED lighting was less than 1/2 for better fixtures with longer warranties so he was happy and I was happy, when I realized how much the fixture price had dropped I felt uncomfortable and reduced my final bill. Let’s just say he paid the full contract price and gave me several more jobs for his company. After the second job I had 2 other contractors ask how I could work for him because he was a jerk. To tell the truth he was quite easy to work with if everything looked neat and he got what he asked for. One of the contractors a friend said but his crazy requirements of everything oversized is nutty enough but labels up no one bid the job. So you can get anything you want but you may end up paying much more for “unusual” requests and not get many quotes. You can get what you want but I don’t know of any electricians that do 3D cad at all and most don’t do more than 1 line drawings. Panel board layout and labeling are a standard part of the job and I do usually make the panel directory on the computer so it is neat and about +10 years ago started providing a thumb drive with the directory for the panel (the thumb drives are inexpensive but home owners love them). The 1 line has the circuit size and approximate length wire lengths for feeders but not usually on branch circuits. One thing I would specify on LED fixtures or lamps that they are DLC approved or have a minimum of a 5 year warranty. And all circuits have a small service loop at each end. Service loops or a few extra inches of wire can make later replacement of parts much easier and in the panel it allows for breakers to me moved around to balance (a good idea if split phase U.S code says well balanced doesn’t give a value ) I shoot for 10% but that’s not always possible. The only other item I can think of off the top of my head would be the box type metallic or plastic. I think metal is the way to go but if you have an opinion make sure it is listed or you will get the cheapest kind available. Sorry this got so long but requesting “exact” info, 2d/3D cad drawings could end up costing a large premium if you get any takers. In my area there is a shortage of electricians to some extent we can pick and choose the jobs we want or put a premium on the bid. I hope my long winded example helps and good luck with your remodel

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  • Not sure EU hs 20A circuits and 15A circuits... 32A ring mains are usual in the UK... – Solar Mike Aug 25 '19 at 8:59
  • @EdBeal Thank you for taking the time to write this. You've made me realize that asking for a detailed plan with CAD drawings would be an exceptional and rather strange requirement for a house. I was somehow thinking that what I am asking for is common for high-quality house projects but looks like it is not. – Andrew Aug 25 '19 at 12:33
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    I did not know the type of power but thought the explanation might help. I did not clarify very well # 10 wire is ok for 30 amp circuits and the doorbell transformer was less than .5 amp with wiring that could support 30 amp. If I did the conversion correctly this would similar to using 12mm wire on your main ring circuit where 6mm would meet the requirements, hope this helps. – Ed Beal Aug 25 '19 at 18:05

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