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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> Consumer board https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1269193378 Message started by doug.com on Mar 21^st, 2010, 5:42pm

Title: Consumer board
Post by doug.com on Mar 21^st, 2010, 5:42pm

Hi everyone, Im fitting mains power to my workshop, its about 70 feet from the consumer board, Ive fitted a house consumer board in the workshop photo to follow of the box, the problem i have is when i plug any appliance into the one socket Ive fitted it trips the box in the house, I've checked my wiring and all OK, NOW... the fuse box in the house has a 80 amp trip and the one in the workshop has 100 amp trip, dose the workshop need a lower main than the house ? or is the distance from the house to the workshop too far and causes the trip, should i hammer a earth bar into the ground and set up a 2nd earth, i do know that if a bulb blows in our house it trips the box. I will put a photo of the house fuse box, then if needed a photo of the fuse box in the shed. thanks. Doug.

Title: Re: Consumer board
Post by Lectrician on Mar 21^st, 2010, 6:07pm

Which is the cable to the shed? Can you mark the Live and Neutral in the consumer unit to show us which ones (use Paint in windows).

Sounds like you have muddled up the neutrals.

If you are feeding the garage from the 30mA RCD side of the main consumer unit you do not need any RCD in the consumer unit in the workshop.

Ideally (depending on installation method of cable), you would have the cable to the workshop ont he NON RCD side of the main CU, and then a 30mA RCD in the workshop CU.

How does the cable run to the workshop?
What type and size of cable?
What have final circuits do you have in the workshop?
What type of loading (equipment) have you got?

Photos are always useful.

Title: Re: Consumer board
Post by The_Trician on Mar 21^st, 2010, 6:09pm

Firstly, I'd like to know what the big black wire is for - the one which comes out of the 4th mcb from the left.

Secondly, I'd like to know what the 4th black wire with what looks like green/yellow sleeving is for - Its the 4th one down when counting from top to bottom on the right hand metal terminal strip.

Also, is there a break in the copper strip hidden behind the long red strip along the bottom of the mcbs? You'll have to switch off to be able to look safely.

TT

Title: Re: Consumer board
Post by doug.com on Mar 21^st, 2010, 6:27pm

This is a photo with the workshop fuse in place, the cable is 6mm twin and earth, im a bit short of time at this moment im off to church in 20 mins but when i return ill post a photo of the fusebox in the workshop and answer the rest of the questions. The cable is underground in trunking

Title: Re: Consumer board
Post by Lectrician on Mar 21^st, 2010, 6:37pm

That MCB is not designed for that board - You should really have the correct type.

That MCB is too large for the cable (B50).

That T+E cable is not suitable for burying, even in duct or 'trunking'.

It looks like there is a break in the busbar, which is a good thing (giving 4 protected ways), but your L and N of your new cable are both on the correct side, so why it is tripping is not obvious at the moment.

More pics required, but I do feel you also have other things to sort out.

Title: Re: Consumer board
Post by doug.com on Mar 21^st, 2010, 10:33pm

got back too late to take any photos, but will tomorow, thanks for some interesting information. Ill change the fuse for the correct type, b32 i think, regarding the cable underground i was told by a electrician this would be fine as long as it was in a sealed trunking, this i did, he works for a housing association, thats worried me a bit now you tell me its not safe as it cost a lot of time and money to get this done. ok ill put more photos up tomorow, regarding the 4th fuse from left, thats a brown wire serving the cooker. and the green is paint on a 2.5 mm and that is feeding a double socket

Title: Re: Consumer board
Post by The_Trician on Mar 22^nd, 2010, 10:07am

How many wires are coming out of the 3rd mcb counting from the left?

The mcb is a B32 and there only looks to be one wire coming out of it.
Also, what size is the wire?

If all it feeds is one socket, you need to change the mcb to a B16A or a B20A.

The 4th one - Niglon brand - needs to be changed for one of a lower rating and it also needs to be the same make as all of the others.

Title: Re: Consumer board
Post by doug.com on Mar 22^nd, 2010, 2:45pm

I'm now running on the left side of the C/u into a b20 amp mcb, it runs the immersion heater but we always use gas, so till i go out and buy a b32 amp mcb it will do for testing, i also moved the neutral to the left, then checked in the workshop and it now works fine, the photo shows the C/u in the workshop, Ive only fitted one socket to start but will be fitting lighting and other sockets to the C/u later this week.

The first photo is with the cover removed (workshop), the second is with cover fitted (workshop), i think i need to buy two blanks to stop fingers getting in, who sells the covers for this type of box?. would it be advisable to fit a separate earth rod to my workshop C/u too? Doug.

Title: Re: Consumer board
Post by The_Trician on Mar 22^nd, 2010, 4:53pm

I don't know where you got the w/shop box from, but it is missing it's bus bar along the bottom side of the mcbs.

Also, what current rating is the RCD?
I'd say that you could do away with the main isolator and just use the RCD as the main switch.
This would liberate 2 extra ways in the consumer unit.

TT

Title: Re: Consumer board
Post by doug.com on Mar 22^nd, 2010, 5:28pm

This Any good? and yes a good idea would leave room for 2 more mcb/s
http://www.tlc-direct.co.uk/Products/MK5590.html?utm_source=shopping.com

Title: Re: Consumer board
Post by Lectrician on Mar 22^nd, 2010, 5:54pm

That socket you have is on a piece of 2.5mm² cable by the looks of it - it should be on no more than a B20 breaker.

Can you tell us where the cables from the bottom of the isolator go - difficult to see which neutral goes where.

Still nothing obvious as to why your RCD in the house trips, unless you have wired the socket incorrectly...

Whats on the 6mm supply cable? Solder drops?

Does the trip pop everytime you turn anything on in the socket? Each and every time? Is it always the RCD in the house, or is it either? Does the same appliance trip the RCD if plugged in in the house?

Title: Re: Consumer board
Post by doug.com on Mar 22^nd, 2010, 10:14pm

OK ill buy that B20 the same time i get one for the house Cu. the neutral and live come from under the isolator to the top of the RCD then the neutral comes out the bottom of the RCD and onto the neutral rail, the live goes on the the base of all the mcb/s that i need a bus bar for.

I checked the wiring twice behind the socket and it was correct, i thought it may have had something to do with the distance from the RCD to the workshop Cu, the RCD in the house is very sensitive, it trips even when a bulb blows in the house. there are earth wires all over the house clamped to every possible point upstairs and down.

the silver on the 6mm cable is tape that was used to keep the coil of wire from getting in knots.

when i had the system running on the RCD in the house it tripped every time "anything" was plugged into the socket in the workshop the RCD in the workshop never tripped, if i plugged the same appliance into a socket in the house it was fine.

I want to thank all of you for giving me your time and skills, your just what i need, this is a fantastic site, I'm going to enroll into my local college for the City and Guilds 2392 Part P, Domestic installers certificate, I've passed my part 1 some years ago but had to leave through ill health.

Title: Re: Consumer board
Post by The_Trician on Mar 22^nd, 2010, 11:56pm

The bus bar in the link you provided is for MK consumer units.

You'd be better contacting TLC and ask them if they do the same spare part for Wylex consumer units.

There should be a model number somewhere on the Wylex board which they will need in order for them to get the correct one.

Looped pieces of wire, whilst fine in most instances, tend to have a habit of coming loose over time. This can cause burning of the mcb terminals.

TT

Title: Re: Consumer board
Post by dj-paul-c on Mar 24^th, 2010, 5:20pm

make sure the supply cable to the workshop isnt damaged at any point ,especially where it enters the fuse boards

also,have you put a socket tester into the twin socket in the workshop ?

if not try that if you have a socket tester,or if you dont have a tester,try changing the twin socket for a different one,then try plugging your items in again
there is a chance it "may" be that

it would probibly only be the rcd in the house that would trip rather than the rcd in the workshop if there is a fault,as it will go back to the origin of the supply first,hence tripping the house rcd