How are your appliances connected

[dj-gabriele]

Brown goods

Brown appliances are DVD, VCR, TV... all the electronics, everything that used to be "brown" in colour and now is silver or black LOL

Hahhahaha

Don't worry, our air-con are all properly sized by the engeneer and my house has fiber-glass insulatinon in the double wall all around the external permimeter, when I tought about "more than an hour" I meant all morning or afternoon after a switch off (like when we are all out)... even if we usually start them in may and the off switch is hit again in september/october.
The first time we had them, it was 1999 or 2000 I think, I was amazed that in only a couple hours of operation the units dumped something like 5 litres of water! I understan what you say about humidity! My parents live in an area where 90% RH is the norm for 300 days a year, terrible! So a dehumidifier runs almost costantly, at times even during winter time when radiators are on.

 

[toggleswitch]

This thread is continued in thread #16408 (yellow section)

"How are your appliances connected #2"

 

[MrX]

There are different types of electricity supply used in different places it depends on a whole range of things including the local geology as that impacts on whether ground rods are effective or not! In some geological conditions there may be serious challenges.

There were also different approaches taken to supply in different eras and in different countries, they're basically all the same and the main thing is that if your system is built to a modern national code and done properly it's usually extremely safe.

In Ireland you basically have two types of supply used.

(3 phase grounded transformer provides this)

In most installations (this is the preferred supply type) we use TN-C-S grounding. Locally referred to as a "neutralised supply." Basically what this means is that an effective ground is achieved as follows:
The power company's neutral is connected to buried earth electrodes all along its route. These are typically at each 'minipilar' where customers are connected to (underground supply) or if it's overhead they're typically grounded regularly at the actual utility poles.

At your house you provide your own grounding system complete with buried earth electrodes too.

All of the ground connections in your house and all of your metal pipework is interconnected to a 'main earth' bar which is connected with a very heavy gauge cable which runs back to the meter cabinet along with your main neutral (blue) and live (brown) cables.

The power company connects the live and neutral to the meter and your ground is interconnected to their neutral at a special connection point before the meter. All this is sealed with anti-tamper seals.

It's more complicated than you'd think!

In general, this type of supply is considered to be extremely safe as the neutral is always ground referenced i.e. isn't floating and also because the supply neutral provides such a solid connection back to the transformer, any 'stray neutrals' caused by faults leaking to earth will be picked up and won't tend to jump along pipework or other metal in the ground.
It also causes any earth leakage to be fairly high current, which trips fuses/breakers quickly.

(3 phase grounded transformer provides this)
The alternative system used in Ireland is referred to as TT
This predominantly crops up in rural areas or where the local supply system is quite old and is not suitable for TN-C-S. Sometimes it's because the system is very reliant on long overhead runs or because the local geology does not permit good grounding everywhere along the network. Also, it was used in some urban areas in the past, but has been largely phased out since the 1960s.

In this case, the customer's grounding system is entirely independent from the network and their protective earth is only provided by local ground electrodes.
The power company supplies Live and Neutral only.

In this case the entire supply has to be fed through a master 2 pole RCD rated at 300mA this is located beside the meter. This is not designed to prevent electric shock, but rather to prevent a situation where a ground fault may not produce enough current to trip a breaker (unlikely but could happen). The consumer also provides RCD protection at 30mA or 10mA on their own final circuits as normal.

Finally there's an IT system.
The transformer does not have a connection to earth i.e. it's "Floating"
This is where the customer supply is isolated from the network completely e.g. supplied via a generator.
This is not normally used at all but occurs when you have your own generator e.g. at a camp site or perhaps at a festival or something.

Also, it is used in hospitals where they may need to avoid any flow back to ground e.g. where heart monitoring or other very sensitive equipment is being used or where there's a risk of introducing currents to the body accidently e.g. in an operating theatre situation.

Special regulations apply in hospitals for this reason.