Garage "Bus Bar" and Cooker?

[markocosic]

Not sure why you want RCD on everything though? belt and braces?

Why wouldn't you want to RCD everything?

*Faulty appliances - dodgy appliances that cause trips and would cost too much to fix?

*Faulty wiring - dodgy wiring that causes trips and would cost too much to fix?

*Cost - splitting lights from everything else is nice, so it doesn't all go dark in the event of a (no lighting) fault, but that adds 50% to the CU cost.

So if you're not a total cheapskate, no reason *not to* do it?


Reasons *to* do it?

*In an ideal world, nobody breaks lights so they don't need protection. In reality - been there, done that, don't want to repeat it...

*The house has switched lighting sockets (round pin) that are connected to wall lightswitches so that you can switch uplighters, bedside lights etc from the wall. These are just as dangerous as any other wall sockets/appliance, no?

So RCD the lighting/heating, which needs two RCDs (or those $$ RCBOs!) if they're to stay on when the washing machine/dishwasher/tumble dryer break down or some metal dust goes through the grinder whilst you're fixing the car and you find yourself under a car in a dark garage full of sharp things...

Could have a main switch in a small enclosure, then to a henley block and to the CUs, each being fitted with an RCD incommer, to keep it neat, henley block in plastic adapatble box and tails in plastic trunking.

Main isolator switch would be in the white box outside, next to the meter - just whack the blocks in there? This box, but for the electrics:

http://www.cosic.org.uk/MarkoStuff/elec/IMG_5986.JPG

 

[Steve]

The regulations state that the only item that requires RCD protection is:

"Sockets that could reasonably be expected to supply appliances outdoors"

And it is always advisable to put your electric shower on an RCD.

Under the scope of this, your round pin sockets dont need RCDing.

If you have sockets under the worktop for washer, dryer etc, these dont need RCDing.

Lights dont need RCDing. (Unless you install emergency lights on the same circuits)

Its advisable NOT to have refrigeration appliances on RCD - run a seperate circuit for inaccessible kitchen sockets, as these dont fall under the scope of the above.

Your garage door and gate opener SHOULD be on an RCD, as I expect it to be quite easy to get a shock off these.

Your cooker needn't be RCD'd, unless it has a socket on its isolator switch. In which case change the switch for one without a socket! Cooker elements develop earth leaks quite frequently.

And dont RCD your central heating!!!! Pumps can develop earth leakage and nuisance trip.

 

[markocosic]

Then the regs are as backward as other UK building regs - only an absolute minimum to avoid being certifiably inadequate - and even you recommend going beyond them for the shower for example, where the regs are clearly lacking but not enough people have been killed by it yet/it's not caused enough financial loss to make it worth changing the law...


Don't RCD them, because they're poorly engineered and regularly fail with a fault to earth? Anything with an earth fault is broken! Domestically some might choose to ignore it until it's bad enough to blow a fuse/trip an MCB/zap anybody who touches the taps - and the regs might deem this acceptable - but I don't!


Everything is on an RCD at the minute (albeit a goosed one it seems, tripping when the 30mA one does) and spurious trips aren't a problem even with the most leakage-prone stuff on the 30mA circuit. Given that overkill hasn't caused any problems in 17/18 years, I'd like to keep it that way...

 

[Steve]

Fair enough. But bear in mind, some devices DO have NORMAL earth leakage. As few as 10 brand new computers can cause a 30mA to trip. Old fridge compressors can develop quite bad earth leakage, but still work perfectly well for years. Anything with a motor can build up carbon on the brushes and leak to the chassis. Again, normal. Its not nessecarily broken.

Shower manufacturers recommend RCD protection for electric showers, for obvious reasons - huge amounts of electricity in a wet shower cubicle with wet naked bodies. And when the 17th edition comes out the rumour mill has it that this will be a new regulation.

Can you see a safety issue with having lights on a shared RCD? You're cooking in the kitchen, your cooker develops an earth fault just as your drunk guest is teetering at the top of the stairs . . . . OR you're showering, when suddenly your shower develops a fault, and trips the lighting in the shower room. Theres nobody else home. You have to fumble about in the dark for a towel, with a wet floor . . . .

Cant you see that certain aspects of domestic installations are inherently safer without an RCD? If not, you're in no position to be replacing consumer units.

 

[ricicle]

The regulations state that the only item that requires RCD protection is:

"Sockets that could reasonably be expected to supply appliances outdoors".

Sockets that can reasonably expected to supply portable equipment outdoors.

If you're going to quote, quote correctly...

 

[Steve]

fnarr fnarr

 

[markocosic]

Fair enough. But bear in mind, some devices DO have NORMAL earth leakage. As few as 10 brand new computers can cause a 30mA to trip. Old fridge compressors can develop quite bad earth leakage, but still work perfectly well for years. Anything with a motor can build up carbon on the brushes and leak to the chassis. Again, normal. Its not nessecarily broken.

None of which are normal in a (well, this at least) house though!

Only offices have that many (cheap and nasty) PCs, fridges that are that old are uneconomic to run ayway and should be chopped in for a new one to save cash, and virtually nothing (power tools excepted, and they usually die of other causes) has a metal chassis these days.

Thanks for the heads-up on bits to choose and the regs - Steve and all.

Cant you see that certain aspects of domestic installations are inherently safer without an RCD? If not, you're in no position to be replacing consumer units.

Honestly, no.

The arguments against boil down to the ability to run appliances with earth leakage (irrelevant in the modern home) and what happens if the lights go out (which is why they'd be on their own RCD). On the for side, you've got protection for lights on ceilings, walls and freestanding units.

Horses for courses. RCBOs for the supremely paranoid, a switch for the ruthless property developer, and everything inbetween.

You clearly have your own preferences, but that alone is not just cause to use irrelevant examples/cast doubt on the capacity of somebody else when their particular solution differs.

 

[Steve]

RCBOs for the supremely paranoid,

Hear that JohnD?

 

[ricicle]

electrical design I'm fine with, sourcing ..... regs I'm unsure of as this isn't something I'd do every day!

Huh?

 

[bernardgreen]

Regulations provide the minimum safety that a committee deem is the minimum that should be in place.

Common sense and experience will provide a better, safer and more appropriate installation by doing more than the minimum as regulated.

When we built our house we lived in a caravan on site and the meter installer refuse to connect to the CU which fed 2 RCDs, one to ring main in caravan and one to a power outlet box on the site. We could only have one RCD by regulations. A call to his boss explaining that we would need working lights in the caravan if we had an RCD tripping accident on the site had the meter installer back the next day to connect us.

We have four RCDs now. The washing machine has its own.

 

[markocosic]

I'm an engineer ricicle - designing an electrical system that'll work is easy, but sourcing bit of household grade stuff/knowing the various standards isn't something I'd do every day. Dicking about (or not...) with HVDC systems and bits at the generation end on the other hand...

Regulations provide the minimum safety that a committee deem is the minimum that should be in place.

Common sense and experience will provide a better, safer and more appropriate installation by doing more than the minimum as regulated.

I'll go with that.