Where And What To Buy Consumer Unit For Newbie

[cyberjunction]

Hi
As some of you know, I am newly qualified and have my elecsa assesment on Friday. I am starting a consumer unit change and have a few questions if I may? Where is the best place to buy consumer units, cable etc. Near to where I live there is a toolstation which is selling twin and earth for a around a tenner cheaper than CEF obviously has BS markings etc and they also have 10 way consumer unit for £40, Brand CTI with 10 MCB's item 71165 or 12 way CED £50 item 12171. My question really is do sparkys only buy from electrical wholesalers and why? should I buy the CTI consumer unit as it will do the job or a wylex for £80 from an electrical wholesaler?

I am on a fast and very steep learning curve but want to start the right way and don't want to buy inferior goods but some of the pricing is quite a bit different and I am trying to understand if there is any point in using electrical wholesalers if goods are cheaper from places like toolstation and even b&q at times, if they have the relevant BS/ES marks.

Also the consumer unit I am replacing only has 5 circuits, is there a problem with putting a 10 way in there or should I be taking out the spare MCB's and replace with blanks? Will the MCB's be compatitble with other consumer units? The 10 way is actually cheaper than buying a smaller box with less which is why I was looking at the CTI one.

many thanks to all and apologies if the questions I am asking are simple but I am going alone so no-one to ask and I would really appreciate the advice from proper sparky's who are doing this everyday

 

[pushrod]

Hi

Also the consumer unit I am replacing only has 5 circuits, is there a problem with putting a 10 way in there or should I be taking out the spare MCB's and replace with blanks? Will the MCB's be compatitble with other consumer units? The 10 way is actually cheaper than buying a smaller box with less which is why I was looking at the CTI one.

many thanks to all and apologies if the questions I am asking are simple but I am going alone so no-one to ask and I would really appreciate the advice from proper sparky's who are doing this everyday

You tend to get what you pay for in most cases and quality kit will be usually be more robust ,better designed and quicker and easier to install.

By putting in a 10 way to replace a 5 way you are future proofing the installation for subsequent addition of circuits. Replacing with the same number of ways would be very poor practice imo. Remove the spare mcbs and put blanks in (keep them for future jobs) and no - not all makes of mcb are interchangeable/compatible with each other.

 

[telectrix]

the main thing is to fit in compliance with regs. i would use a wylex 10 way, £76 inc. vat and loaded with 2 RCDs, 8MCBs. split circuits between RCDs. watch out for borrowed neutral in landing light.

 

[cyberjunction]

thakns for your prompt replies, its so hard to get help when starting out, this forum is great and I appreciate all feedback - thanks

 

[cyberjunction]

the main thing is to fit in compliance with regs. i would use a wylex 10 way, £76 inc. vat and loaded with 2 RCDs, 8MCBs. split circuits between RCDs. watch out for borrowed neutral in landing light.

sorry for the daft question but what is meant by borrowed neutral? I read up on this but a little confused thanks

please excuse my ignorance as its my first job

 

[cyberjunction]

i have a basic understanding of this and it is said the easiest way to overcome this is to place all lights on the same mcb, is this a could idea? not good practice I'm sure

i will go and have a look and will be off line for most of the day so many thanks for the replies. I am learning on the job and I am sure it wil be obvious once I am there - cheers

 

[telectrix]

it's not hard to get help if you know where to look. this forum is the best place. by the number of posts you have made so far, you will know the extent of the knowledge that is on here. i like to think that i have a small percentage of it. anything you need ( except money, LOL ) feel free to ask. form my experience, a lot of the younger guys, having obtained qualifications to the nth degree, are lacking in practical expertise, but that comes with time on the tools.

for assessment, you need to get it right so pay a bit more for a quality board. make sure everything is labelled up, all your test results 100%. and most importantly, demonstrate safe working practice, safe isolation etc. and good luck with it.

Cheers, Tel.

 

[zedess]

when u change a consumer unit the phase AND neutral of that circuit must be on the same rcd side, if some one has previously borrowed a neutral from say upstairs lights for downstairs lighting circuit then the rcd will trip..cos they arent on the same side!!.......good advice from telectrix..cos they can be a sod!

 

[zedess]

and no its not such a good idea to stick all the lights on the same rcd...its a short cut!..........if that rcd goes your looking for a candle....in the dark...not good if your a pensioner in a zimmer frame

 

[telectrix]

i prefer to call it a borrowed live. as what has been done a lot in the 70's was: landing light ( 2way ) is wired as an upstairs light ( in the attic ) but the live is taken from the 2 gang hall/ landing switch. this means that if you wire the upsiars and downstairs lights on differenf RCDs, when you switch on the landing light, it takes it's live from 1 RCD and the neutral from t'other. this creates an inbalance on both RCDs so more than likely, both will trip. the answer is to remove the live feed from downstairs and re-supply from upstairs circuit. if this can't be done ( due to decoration or whatever ) you have to put both lighting circuits on the same RCD. this defeats the object of separation of circuits. but as a last resort may be your only solution.

 

[mattmoo1974]

Cyber put a split board board in 10 way.
Have the upstairs lights and down stairs ring on 1 side and viasa versa, So then if a RCD trips you dont loose every thing up/down stairs.
IE if some 1 plugs in a kanckered say kettle into the downstairs ring and it trips the RCD on that side of the board,they will still have the lights on because the lights are on the other RCD on the board.
Hope that made sense to you

 

[Geordie Spark]

Cyber put a split board board in 10 way.
Have the upstairs lights and down stairs ring on 1 side and viasa versa, So then if a RCD trips you dont loose every thing up/down stairs.
IE if some 1 plugs in a kanckered say kettle into the downstairs ring and it trips the RCD on that side of the board,they will still have the lights on because the lights are on the other RCD on the board.
Hope that made sense to you

Have a looksee at page 4 of this: http://www.electrium.co.uk/Wylex17th Edition.pdf

 

[pushrod]

If you can't immediately sort out a borrowed neutral, rather than having both lighting mcbs on the same side ie through the one rcd, it is better(safer) to put both lighting circuits on the same mcb. This is because although putting them on the same side will stop the tripping it will mean that with 2 separate mcbs if one mcb is switched you might not have completely isolated that circuit because of the other. Obviously you will have to make assessments of load to check if this is possible.

 

[tony mc]

Some excellent advice given by all and none of your questions are stupid.
I bet lots of people out there are reading this but did't like to put a post on the forum.

Remember the borrowed neutral every time you are working on any cct and treat the neutral the same as the line and you will stay safe.

 

[white armour]

Have used both CTI & CED as my supplier had them on special, was not very impressed at all; cheap and cheerful. Have used a lot of Niglon twin RCD boards over the last couple of years (compatible with Hager) and found them to be good quality, robust and not too bad at all to work on. Always try to leave 2/3 spare ways for future use and take any unused MCBs away for future use.

I try to stick to fitting 2 or 3 make of CCU otherwise you with have loads of different MCBs knocking about cluttering up van/shed/garage etc. Also like the Crabtree starbreaker range, little more pricey but excellent kit.

If you fit CCU that accepts RCBOs this also helps with the borrowed neutral scenario as you can stick both circuits in without affecting sockets if you get a trip, I only to use this a a last resort and try and resolve the errant cabling by routing through airing cupboard or slimline trunking behind bed doors if this is acceptable to customer.

Best of luck with your assessment.

Regards wa

 

[ezzzekiel]

the usual method is to move the existing light wiring at top of stairs into junction box just leaving the single core switched live at the rose, then run a neutral from downstairs lighting up to the fitting.

as for buying gear dont use places like the sheds etc, find a local wholesaler go introduce yourself and build up a reputation with him.