new shower trips main rcd

[dunc]

We have moved into a house with a new looking Mira shower. However with the powr light on the shower lit up all seems ok. Press the start button and it trips. using a meter I get a buzz between neutral and earth on the heater tank.
Any ideas?!

Cheers,

Dunc

 

[andy]

We have moved into a house with a new looking Mira shower. However with the powr light on the shower lit up all seems ok. Press the start button and it trips. using a meter I get a buzz between neutral and earth on the heater tank.
Any ideas?!

Cheers,

Dunc

what trips? the MCCB at the local substation?

and you say get a buzz between neutral and earth. does that 'buzz' indicate voltage or continuity? is the power on or off?

also, how is my car doin on fuel?

 

[Qedelec]

I assume you are using a buzzing continuity tester so you nave a short between neutral and cpc.
The shower will be on a RCD so it is detecting the short to earth.
Disconnect the shower and check for a short from neutral to earth.

 

[dunc]

I realize what I have done, connected the neutral in the split load to the wrong buzz bar.....
Works fine now but trips the 30a mcb which I think I need to change for a 40a?

Cheers for the replies!

Dunc

 

[ban-all-sheds]

I realize what I have done, connected the neutral in the split load to the wrong buzz bar.....

Thought you said you'd just moved in and the shower was there?

Works fine now but trips the 30a mcb which I think I need to change for a 40a?

What you need depends on the shower.

What you can have depends on the cable, and how it is installed.

Let's hope the two don't conflict, eh? //www.diynot.com/forums/viewtopic.php?p=81696#81696

What are the rating of the shower and the size of the cable?

 

[andy]

Thought you said you'd just moved in and the shower was there?

sounds like they only put the shower in and the cable upto the CU

 

[dunc]

Hi,
yes, when we moved in there was an [apparently] connected shower. That is it had a cable [6mm] connected. Not sure why but this had never been connected at the CU so amidst millions of other jobs quickly connected it to see if it worked. When it didn't I put 2 and 2 together and got 5. Assumed that it had been disconnected because it was duff.
I still don't know why it was not wired to the CU.
Its an 8.5kw which I think is over the limit for 6mm? What is the correct type an fuse rating for 8.5. Also what is the current capacity of 6mm in normal operating conditions/

Ta

Dunc

 

[ban-all-sheds]

What is the correct type an fuse rating for 8.5.

Can you work out 8500 ÷ 240 ?

Also what is the current capacity of 6mm in normal operating conditions

These figures are not quite the same as the ones for flat T/E cable, but they are pretty close:

http://www.tlc-direct.co.uk/Figures/Tab4.7.htm

 

[Hacman]

8500 ÷ 230

 

[Softus]

8500 ÷ 230

Have you measured your own consumer supply recently? Mine is 240V.

Also, I asked my provider what the specified supply should be, and they said 240V -6% + 10% (or something like that).

So the minimum in the UK is more like 225V than 230V. For I realise the the EU requirement is different, but I have no idea whether or not the UK is illegal.

 

[ban-all-sheds]

8500 ÷ 230

I guarantee you that when a shower maker specifies "8.5kW" for his product he means at 240V. Which is what we have in practice.

But if it makes you any happier:

"Can you work out 7800 ÷ 230 ?"

So the minimum in the UK is more like 225V than 230V. For I realise the the EU requirement is different, but I have no idea whether or not the UK is illegal.

For many years the supply voltage for single-phase supplies in the UK was 240V +/- 6%, giving a possible spread of voltage from 226V to 254 V. For three-phase supplies the voltage was 415 V +/- 6%, the spread being from 390 V to 440V. Most continental voltage levels have been 220/380V.

In 1988 an agreement was reached (CENELEC Harmonisation Document HD472)that voltage levels across Europe should be unified at 230V single phase and 400V three-phase with effect from January 1st, 1995. Those countries with a nominal voltage of 240V (like the UK) were obliged to move to 230V +10% -6%, and those on 220V moved to 230V +6% -10%.

It was proposed that on January 1st, 2003 the tolerance levels would be widened to ±10%, and then that was pushed back to 2005, and then in July 2001 the CENELEC Technical Board decided to continue with the existing tolerances until 2008.

In any event, the European-wide harmonisation is not being done by having common supply voltages, but by requiring manufacturers to make products which operate over a much wider range. Since the present supply voltages in the UK lie within the acceptable spread of values, Supply Companies are not intending to reduce their voltages in the near future. This is hardly surprising, because such action would immediately reduce the energy used by consumers (and the income of the Companies) by more than 8%, although when the system is under heavy load the generating companies happily take advantage of the lower limit.

 

[Spark123]

The iee regs still use 240v in their calculations, if its good enough for the its good enough for me