Regs Question.

Tuco88

Hi, I was told recently that shower circuits over 20m in length have to be supplied in 10mm^2? Now I know its obvious the length and load have a say. I cant spot this in the regs or if there was an update nothing on the ECTI site. My own place has an 8.5kw shower supplied in 6mm^2 over 20m and has been fine for the past 12 years...

Is it a RECCI/ESSA rule? I know some of them like to try and force there own ideas.

Another was switch circuits, That its not allowed to have two separate circuits at a 2gang switch?

Cheers, I know silly kind of questions, but would would love to know if there was an update on anything.

Sir Arthur Daley

I use 10mm square anyway because the customer could land with anything.
The 2 gang switch same circuit criteria is the first i have heard anyway.

Tuco88

Yeah I agree, I hate it when guys "hear" you have to do it x y and z now and its all just BS its mostly from the guys who dont even have the book. I would be more annoyed if I missed the update : )

2011

Tuco88 wrote: »

Hi, I was told recently that shower circuits over 20m in length have to be supplied in 10mm^2? Now I know its obvious the length and load have a say. I cant spot this in the regs or if there was an update nothing on the ECTI site.

The National Rules for Electrical Installations (ET101:2008) does not explicitly state this. What it does do is provide you with the information required to select the correct cable size.

Here are the conditions that you have to meet:

433 States that the continuous current carrying capacity of the cable must be greater than or equal to the rated current of the protective device. It also states that the protective device rating must be greater than or equal to the design current of the circuit. So start by calculating the design current. A B type MCB (or RCBO) would be best if your aim is to keep the cable size as small as possible.

According to Table 41A a disconnection time of 0.4 seconds is required for a 230VAC TN system. Too small a cable size will result in the earth fault loop impedance value being too high to achieve this disconnection time.

525.2 states that the maximum permissible volt drop must not exceed 4% of nominal voltage (for installations not greater than 80A). Too small a cable size will mean that the volt drop will be excessive.

If all of the above conditions are met then the cable size is in complacence with the regulations.

mikeyjames9

the first one.. not an etci rule

it's in some of the shower manuals

the rules mentions checking length of shower cable


521.8.3 mentions different circuits in a junction box
I would avoid having different circuits in a domestic light switch.. I dont see any rule though

chuckyarelaw

<MOD SNIP> This is not After Hours, please keep this in mind when posting. Thanks.

mikeyjames9

I don't think there's any prohibition on multiple circuits at light switches
It would be common on grid switches

It can also be permissible to have more than 1 circuit in a multicolore cable

there appears to be a rule covering junction boxes and partitions(521.8.3)

Sir Arthur Daley

I fail to see any disadvantage in this switch theory anyway.

Tuco88

Cheers lads, for the info.

mikeyjames9

on domestic work some untrained persons may only switch off 1 breaker
when changing a switch

on com/ind work there was usually trained electricIan's on maintenance

Sir Arthur Daley

mikeyjames9 wrote: »

on domestic work some untrained persons may only switch off 1 breaker
when changing a switch

on com/ind work there was usually trained electricIan's on maintenance

I was thinking about this earlier too. Even an untrained person should use logic and isolate power on the db with reference to what each switch is doing.

mikeyjames9

I believe in the UK they may be required to leave a warning notice inside a domestic switch box if doing this

I've seen mention of it on the UK forums

Sir Arthur Daley

mikeyjames9 wrote: »

I believe in the UK they may be required to leave a warning notice inside a domestic switch box if doing this

I've seen mention of it on the UK forums

I don't know, i have no knowledge of UK rules or regs.

mikeyjames9

Sir Arthur Daley wrote: »

I don't know, i have no knowledge of UK rules or regs.

I know you've mentioned it previously

I have a copy of et101 and some knowledge of bs7671

a comparison with other countries regulations may form part of the discussion occasionally

Sir Arthur Daley

mikeyjames9 wrote: »

a comparison with other countries regulations may form part of the discussion occasionally

Im not knocking you for bringing it up, which country has a better setup overall do you think?

mikeyjames9

not sure if I'm qualified to say
I'd have to think about it anyhow

the UK rules seem more comprehensive and logical

we seem to have a lot of arbitrary rules here designed to idiot proof installations

Sir Arthur Daley

It wouldn't suprise me if the UK were, take their education system its leaps and bounds ahead of ours.

Bruthal

mikeyjames9 wrote: »

I would avoid having different circuits in a domestic light switch.. I dont see any rule though

Landing switches for bathroom and landing light, two separate switches?

If we are going to that level of protecting diy people, then its time for 12 volt electrics in a house.

brightspark

mikeyjames9 wrote: »

I believe in the UK they may be required to leave a warning notice inside a domestic switch box if doing this

I've seen mention of it on the UK forums

It's in the Irish Regs

537.5.5
.....
....
A wall mounted switch assembly connected to more than one circuit shall be provided with an appropriate permanent, indelibly marked warning notice, which may be affixed inside the enclosure

mikeyjames9

yes it's an amendment

didn't see it
http://www.etci.ie/docs/et101a12011.pdf
page 114

Stoner

OP its also something that can come up in local authority regulations, so if you were working on council houses their inspector will have his/her own specification on it, so I think it a source for a lot of these things that you rightly bring up, alternative specifications.
The other debate here was always where the feed for the landing light was fed from, the upstairs of the downstairs lighting circuit, back in the day when houses only had two lighting circuits.