Electrical Phrase/Word of the Day

Paul.M · Jul 16, 2015

Each day anyone can post a new electrical word or phrase with a brief description for it. This is not restricted to only one a day by the way, more the merrier. If a debate starts up and looks like it may over run this thread please start a new thread for that subject to keep this one clean and easy to follow for other members in time to come.

Band I & Band II Circuits.

Band I are SELV, PELV, telecommunications, data and signalling not exceeding 50V ac or 120V dc.

Band II is 51V ac - 1000V ac (low voltage) or 121V dc - 1500V dc. (look up ref 7.4.1 OSG)

When installing band I and II cables we have to keep them separated. This can be achieved by a distance of 50mm or having them in separate compartments (trunking/conduit etc). We can also achieve electrical separation by the use of "an earthed metallic barrier" or a none conductive barrier (bit of plastic lol). This will prevent mains voltage appearing in Band I cables. Also prevents Band I signal cables from having their data stream interrupted, eg My house! TV installer (before we bought the house) ran his TV coax under the floor void and cable tied it to the 6mm T&E cooker circuit. Every time the oven was turned on the TV signal got a bit scrambled!!!

Well that is a good bit of info to get this started, who will be next?

D00DY_T00DY · Jul 19, 2015

Class I and class II electrical equipment
Class I products have protection from electrical shock by having its metal body earthed. So if you're unsure if a piece of electrical equipment is class I or class II if it has exposes metal parts chances are it's class I.

Class II have protection by being double insulated to prevent shocks, this is things such as drills(newer drills. Old drills were mainly all metal "back in the day") and can be identified by a logo on its product details of a square inside a square.

When Portable Applience Testing you are certifying that they're safe for use by testing class I and class II products (which is very very. VERY boring... In my opinion)

Resu · Jul 19, 2015

D00DY_T00DY said:
Class I and class II electrical equipment
Class I products have protection from electrical shock by having its metal body earthed. So if you're unsure if a piece of electrical equipment is class I or class II if it has exposes metal parts chances are it's class I.

Class II have protection by being double insulated to prevent shocks, this is things such as drills(newer drills. Old drills were mainly all metal "back in the day") and can be identified by a logo on its product details of a square inside a square.

When Portable Applience Testing you are certifying that they're safe for use by testing class I and class II products (which is very very. VERY boring... In my opinion)

What about class 3?

Paul.M · Jul 20, 2015

Resu said:
What about class 3?

He will learn that on his 2nd year lol

Resu mate, you write it up if you want?

davesparks · Jul 20, 2015

D00DY_T00DY said:
Class I and class II electrical equipment
Class I products have protection from electrical shock by having its metal body earthed. So if you're unsure if a piece of electrical equipment is class I or class II if it has exposes metal parts chances are it's class I.

Class II have protection by being double insulated to prevent shocks, this is things such as drills(newer drills. Old drills were mainly all metal "back in the day") and can be identified by a logo on its product details of a square inside a square.

When Portable Applience Testing you are certifying that they're safe for use by testing class I and class II products (which is very very. VERY boring... In my opinion)

Metal cased class 2 appliances are pretty common too.

D00DY_T00DY · Jul 20, 2015

No idea class III existed...
Class III is equipment powered by SELV therefore have no risk of electric shock(Thank you wiki)

there's also class 0 which has no protective earth and is single insulated but have been prohibited from sale pretty much everywhere due to it being unsafe.(Again, thank you wiki)

Class I logo