TT supply consumer unit.

[neil2jo]

hey plug, do you own the osg? because on the front page it reads on-site guide BS7671 :2001 (2004) wiring regulations including amendments....
I beleive that then makes it BS7671??
I also believe that the OSG guide was create for quick everyday reference using the full bs7671
If you then read about earthing a TT sytem the rods Ze will fluctuate according to the weather i.e if the ground is dry there will be minimal contact with earth whilst if wet there will be greater contact with earth.(it has been known for sparkys to 'wee' on the rods before testing to improve results). It then will tell you that if you have a earth loop imped which is too high (bad, to be expected with dry earth) that a 100ma is required...As the weather will be expected to dry at some point, even in england, you fit a 100ma as standard..now
The timer delay side is if you have a 30ma rcd on the board to protect the other circuits, which you would have (or is that something you don't do as well, tut tut). Surely you can work out why.
Now answer me this plug ....ARE YOU PART P REGISTISTERED??
If no I will not bother replying anymore, unless you wish to pay me training fees, if you don't answer I'll take it as a no.
If yes call the NIC they will confirm it for you...i'm not doing all your ground work!! and maybe get a refresher course

 

[ban-all-sheds]

hey plug, do you own the osg? because on the front page it reads on-site guide BS7671 :2001 (2004) wiring regulations including amendments....
I beleive that then makes it BS7671??

Maybe your lips get tired from all that moving, and you have to stop before you get to p8.

If you ever do make it that far, you'll read this:

The scope generally follows that of BS 7671. It includes material not
included in BS 7671, provides background to the intentions of BS 7671,
and gives other sources of information.

However, this guide does not ensure compliance with BS 7671. It is a
simple guide to the requirements of BS 7671, and electricians should
always consult BS 7671 to satisfy themselves of compliance.

Now answer me this plug ....ARE YOU PART P REGISTISTERED??

If you believe that being registered means that a person is competent, or that not being registered means that they are not, then you're an even bigger fool than John Prescott.

 

[plugwash]

The timer delay side is if you have a 30ma rcd on the board to protect the other circuits

yes time delay is required if you feed the rcds in a daisy chain arrangement to ensure discrimination between them

however it is perfectly possible to set up a CU such that the rcds are NOT in a daisy chain arrangement which should eliminate the need to use a time delay.

for example a setup with a main incomer switch feeding two totally seperate RCDS http://www.electrium.co.uk/download_file.asp?Type=C&Company=3&Id=11 top of pdf page 1 (page number printed on page is 119)

another way would be to use a split load CU with a main switch and a 100ma rcd put the low risk cuircuits on the rcd side and put the high risk cuircuits on rcbos on the non-rcd side.

 

[ban-all-sheds]

The Hager drawing is better, as it's larger and in colour, but it's the same idea as the Crabtree:

 

[neil2jo]

the hager drawing is also permissable just seem like a waste to have the extra isolator and wiring which would take up 2 prescious mcb slots.
As with sheds- you will alos know then with your vast knowledge of electrics that my supporting statemnt re weather condition poor Ze etc, then supports the statment re 100ma rcd (optional timer delay), or do you not practice environmental/thermal effects?

 

[ban-all-sheds]

Extra isolator & slots are pretty cheap.

Crucial thing is that if you don't have an RCD incomer for the whole board you don't need a fancy time delayed one for discrimination purposes.

Could get the same effect with two separate small CUs, one with 30mA for sockets, one with 100mA for the rest....

 

[neil2jo]

Personally I would only fit one consumer, particularly as space is often an issue, costs are the same, £60 for another board, £60 for a timer dalyer.
The rcd senario you give is valid to an extent, however the rcd required is only required for 2 main reasons a)bathrooms using 230v in zone 1 or b)outlets which are likely to be used for partable outdoor equipment.
The reality is 9 out 10 homes will use an outlet for lawnmowers/radios/car tyre pumps etc etc. I fit them as standard on split boards to meet regs and to ensure the customer is safe, again you are talking on a loaded board an extra £10. Ask the customer life or £10??

As with the part P a few messages back, I like you (presumably) have been doing electric now for around 10 years +, got the 16th etc etc. When the part p come out i registered and attended a refresher course to catch up with regs. I found out that although what I was installing was safe it was under todays standards and needed to do more. The other 11 person also attended, alos felt the same. The difference between part P and sparky of 25 years is likely to be, sparky indeed is quicker probably tidyer and has a much better alround knowledge, however this part p is now setting some standardswhich I think you'll find a lot of people now fall behind in. Since going on that course I dont think I have been to one house where I could not see bad workmanship or failed standards/regs. Its an eye opener. of course not my jobs

Something for peoples knowledge, which I have not met a sparky who agrees, yet 2 inspectors and a course training say is now regs.
When fitting a consumer if you use the top knock outs, on completion if a 1mm cable can access, through the top, into the consumer it has failed, due to the IP codes. Lets just say when I got told I gulped.

 

[TeesdaleSpark]

Mu On-Site Guide shows both ways of doing it. i.e. with a 100mA time delay RCD as the main switch and also with an isolator as the main switch feeding a 100mA and 30mA rcds.

 

[Clitheroe]

If by any chance you get a Wylex Time Delay RCD, whether you put it in a Wylex consumer unit or in a seperate enclosure before the consumer unit if the consumer unit is another brand, then the part number for the Wylex T/D RCD is WRMT100/2 and not WRM100/2.
The reason I am telling everybody this is because just before I installed my Wylex consumer unit which I purchased from screwfix, I went to the wholesalers and asked for a 100Amp 100mA Time delayed RCD. When the chap behind the counter came with a Wylex RCD it had 100A 100mA on it so I asked "Isn't this supposed to have Time delay or S on the front of it ?" He said "It is a Time Delay RCD" and I bought it.

A couple of weeks after installing the RCD and CU etc I had a fault on the toaster which tripped the 30mA RCD like it should but also tripped the 100mA which I then realised I had been sold the wrong thing and was very annoyed at it.

I explained what had happened and another person in the same place said "Thats not a time delay one" and ordered me a Time delay RCD.