What applications are 10ma RCD's required in?

[eveares]

Just wondering what if any applications are 10mA RCD's/RCBO's required/mandated in and whether BS7671 says anything about 10ma RCD's/RCBO's being required in certain applications?

My first thought is is in applications where one is regularly working on live equipment such as in factories,electronic workshops, etc... as a extra precaution along other things like isolation transformers and general working practices.

Also read that they are sometimes used in schools.

Regards: Elliott

 

[bernardgreen]

Medical equipment which has direct contact with a patient such as heart monitors normally has a 10 mA RCD.

 

[eveares]

Is that a requirement stipulated by the manufactures of the medical equipment? How about in high risk electronic workshops?

 

[Taylortwocities]

The college where I did my 236 had 10mA RCDs to protect the supplies to the electrics installation workshop benches, for obvious reasons!

 

[eveares]

for obvious reasons!

Makes sense, to have them where there is a high risk or are stipulated by the manufactures of equipment.

What does BS7671 say on them if anything?

 

[Taylortwocities]

What does BS7671 say on them if anything?

Don't you have a copy??

The RCD Handbook - Beama will tell you everything you need to know.

IIRC, in the US, their general use RCDs (GFCI) are rated at only 5mA with an allowable trip time of 25mSec. A lot less than our 30mA/40mSec.

 

[bernardgreen]

Is that a requirement stipulated by the manufactures of the medical equipment?

As I recall it was a medical council ( British Medical Association ? ) requirement.

How about in high risk electronic workshops?

True engineers wouldn't need to be protected

to protect the supplies to the electrics installation workshop benches, for obvious reasons!

Remove them and sort out the potentially poor electricians ?

 

[JohnW2]

IIRC, in the US, their general use RCDs (GFCI) are rated at only 5mA with an allowable trip time of 25mSec. A lot less than our 30mA/40mSec.

25 ms certainly offers more protection than 40 ms (although I've rarely seen any 30mA RCDs which take anything like 40 ms to operate at 1 x IΔn in general use", I don't know that the difference between 5mA and 30mA will make much practical difference in terms of electric shocks which actually happen (as opposed to one that may be prevented). As you know, the current through a person is the current through the person (dependent only on potential difference and the total impedance of the path through the victim), regardless of the trip threshold of the RCD - the RCD can obviously only limit the duration, not the magnitude, of the shock current.

Medical equipment etc. obviously presents issues different from those of RCDs "in general use".

Kind
Regards, John

 

[ericmark]

I have used them to prevent faults tripping the 30 mA RCD on items likely to have leakage problems like the supply to a pond. Where insulation slowly degrades the 10 mA should trip first.

As to electronic workshops not sure if the capacitive and inductive links when working on a live chassis would allow their use? In workshops it's normal to allow the worker to select which socket is used and any 10 mA RCD is built into the socket. But don't press the test button on MK types as it will trip the main 100 mA feed RCD as we found out.

 

[eveares]

Don't you have a copy??

No, I am not in the Trade and it is rather expensive. I have looked on-line in the past to see if someone has leaked it, but had no luck finding the recent versions.

in the US, their general use RCDs (GFCI) are rated at only 5mA

Now that I did know.

True engineers wouldn't need to be protected

True, but one can never be to careful. What happens if you have an apprentice/beginner in and does not use a isolation transformer/good practices.

sort out the potentially poor electricians ?

True, but again one can never be to careful.

 

[Risteard]

My first thought is is in applications where one is regularly working on live equipment such as in factories,electronic workshops, etc...

How would you justify "regularly working on live equipment"?

 

[eveares]

How would you justify "regularly working on live equipment"?

Love how you come here after I criticize your post on the "Appliance Fuses" thread; And for working on live equipment, easy - your fault finding on some piece of complicated mains equipment that needs to be live when testing. i.e. mains chassis TV for example what has multiple voltage rails.

 

[Risteard]

It's the "regularly" part that is particularly alarming.

 

[eveares]

It's the "regularly" part that is particularly alarming.

Not if your a service tech and you repair that sort of equipment (like mains chassis TV where you need to test internal voltage rails for example.) day in and day out for a living.

 

[stillp]

It's the "regularly" part that is particularly alarming.

Not if your a service tech and you repair that sort of equipment (like mains chassis TV where you need to test internal voltage rails for example.) day in and day out for a living.

Where's your isolating transformer?