In Ireland every socket circuit must have earth leakage 30mA.

In UK we rely on EEBADS to protect people & livestock against shock risk from indirect contact

For circuits supplying socket outlets the protective device must disconnect the circuit under fault conditions in 0.4 seconds or better

We can install a 30mA RCD on the circuit to provide protection against shock risk but EEBADS is the accepted approach

For sockets feeding equipment outside the equipotential bonding zone we must install a 30mA RCD

However Part 6 of BS7671 IEE wiring Regs does identify certain locations i.e. construction sites & agricultural installations where a more stringent approach is specified because of the increased risk of an electric shock

Hmmm.....  the numbers all seem high to me for personnel protection, compared to what we use here in the US.

Here we use 5mA GFI for personnel protection.  Period.  5mA is generally safe.  5mA protection is required for all outdoor receptacles and near sinks, water, etc, for indoor receptacles.

Anything set to protect over 5mA is considered equipment protection.  30mA breakers are typically used for heat-tracing circuits, for example.

See Thread238-35719 for a discussion of the effects of various levels of current through the human body.

I agree peebee most standards I've worked with generally require 3.5 to 5 mA depending on the type of product.

Christopher Caserta
ccaserta@us.tuv.com
Ph:904-225-0360

In the UK its assumed that a PC leaks about 2mA to earth through filter circuits. Therefore three items would trip a 5mA RCD. Is this a problem is the US?

There's very very few PC's on GFI circuits here, so no, it's not a problem.  It might well be if you tried to run a PC off a GFI, though.

I have heard that the SCR temperature controllers in commercial radiant ovens can trip GFI's, though.  I think the actual culprit is a filter that they provide in front of the SCR's; that filter is typically grounded to the chassis.  The ground current is enough to trip a GFI receptacle.

best protection is selective protection where main circuit can be protected with sensitivity 0.3A, subcircuits with 0.03A and each circuit with 0.01A.

Welshwizard,

Okay, being a dumb Yank, I have to ask:  What is EEBADS?  

Quote:

Earthing    Method of connecting most exposed metal work in a building and metal appliances to electrical Earth - nominally 0V. Windows and shelves are normally excluded but most metal pipes etc. are included. This means that in the event of a fault - eg. Live wire touching a metal case, then the earth will facilitate automatic disconnection of the mains supply (known as EEBADS * in the trade). This should cause the circuit protective device - fuse to blow, or MCB to trip. Country properties often have an Earthing rod to provide some protection - usually with an RCD as well.
In the wiring regulations the earthing wire is referred to as the CPC - Circuit protective conductor.
(CPC is also the initials of a supplier - Combined Precision Components).
* EEBADS stands for Earthed Equipotential Bonding and Automatic Disconnection of Supply.

from: http://basic1.easily.co.uk/039069/01C053/electrical_glossary.htm

TTFN

I think a 100mA RCD, in the UK at least, would be confined to providing earth fault protection to a TT installation where the utility does not provide an earth conductor and the protective earth is a ground rod or similar. The low fault level typical of this type of installation does not guarantee that the 0.4s disconnection time requirement can be met, so the RCD is used to ensure rapid disconnection in the event of a ground fault.

If the installation incorporates 30mA or 10mA instantaneous RCDs for personnel protection, it is permitted to use a 100mA time-delayed RCD as the incoming device for overall ground fault protection for the installation, thus providing discrimination between the incoming device and the individual circuits.


30mA is the standard for personnel protection, with 10mA recommended for increased risk situations. 100mA is not suitable for personnel protection, whether time-delayed or not.

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