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Topic Title: Using 10mA RCBO's
Topic Summary: Stables
Created On: 30 September 2012 10:22 AM
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 30 September 2012 10:22 AM
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primo

Posts: 454
Joined: 10 January 2008

Should I expect any earth leakage from HF T5 twin 5ft fittings?

I plan to install on a circuit that will be protected by a 10mA RCBO or may install multiple circuits. Probably being over cautious but this installation is in stables and although the fittings and cabling will (should be) out of reach I'm erring on the side of caution.

Cheers.
 30 September 2012 10:28 AM
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daveparry1

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I suppose it depends on how many fittings are going on the circuit Primo,

Dave.
 30 September 2012 10:33 AM
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primo

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Indeed!

3/4 max I would say. But I have no idea how leaky these fittings are.
 30 September 2012 12:01 PM
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daveparry1

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http://www.saudilighting.com/techinfo/6-6.htm
------------
Some info here that might help you Primo.
 30 September 2012 01:12 PM
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slittle

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Whilst I can understand the 10mA thinking, A couple of thoughts spring to mind.


Given that they should be "out of reach" and the cabling will I'm sure be in conduit or similar, what are the increased risks to the lights suddenly tripping due to leakage (that maybe wouldn't have upset a 30mA or 100mA RCD) when the vet has his arm somewhere unpleasant on a dark night.

Personally, I'd consider 10mA protection for socket outlets used for clipping etc, but I think lighting might be a bit OTT.
Also what's the upstream device ??. Bear in mind with RCBO's fun things can happen under fault conditions if they are not double pole.




Stu
 04 October 2012 09:00 PM
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eclectica

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Leakage from HF kit (including LED drivers!) can, and does, cause tripping to regular RCDs - the higher the frequency the greater the effect of parasitic capacitance and especially with long cable runs from the drivers.

I recall Schneider Electric do a range of HF immune RCDs.

Hope this helps

Regards
E.

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 06 October 2012 04:31 AM
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loftyloo

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ive used double pole 10ma rcd just for clipping, and left the others proctected by individual 30ma rcbos.




lofty
 06 October 2012 02:43 PM
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weirdbeard

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Originally posted by: primo

Should I expect any earth leakage from HF T5 twin 5ft fittings?



I plan to install on a circuit that will be protected by a 10mA RCBO or may install multiple circuits. Probably being over cautious but this installation is in stables and although the fittings and cabling will (should be) out of reach I'm erring on the side of caution.



Cheers.


Hi primo, I think you are being a bit too over-cautious - is there really any need for any type of RCD for the lighting at all unless it's a TT system? (and in case spinlondon reads this, I do realise that you can have a TT system without RCD in some circumstances, though RCD is the preferable option.)

Whilst I've no problem with installations that exceed the requirements of the regs, there's always a remote possibility with any installation that there may be an unaccountable accident that causes a problem with even the most robustly installed wiring system - to design protective measures that aren't required by the regs might suggest that you are expecting failure of your wiring system?

I think I know where you are coming from though, I think its the social stigma attached to horse ownership, which is generally related to the more affluent parts of society, and the information that animals are more sussepitible to shock than people, but for example in the reply by loftyloo about using a 10mA rcd for clipping only - who is that there to protect - the horse or the person holding the clippers? (which life is more valuable in reality, regardless of the perceived market value of the horse?) Battery operated clippers for horses are widely available and are much safer than mains operated ones!
 08 October 2012 08:21 PM
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primo

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Thank you all for your very useful posts.

Good document Dave.

Thanks for the reality check post wierdbeard, easy to get carried away.

Stu, upstream device is a 100mA time delayed RCD. Final circuits are at present 30mA SP RCBO's, no 10mA as the CU is Wylex and they don't seem to make one! Memshield 3 RCBO's fit with a little help from a hacksaw ()

What fun things are we talking about? I'm sure you've been through it on other posts but I can't remember and search facility doesn't seem to be working at the moment.
 08 October 2012 08:28 PM
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weirdbeard

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Originally posted by: primo

Thanks for the reality check post wierdbeard, easy to get carried away.


No probs.



search facility doesn't seem to be working at the moment.


See the topic below:

http://www.theiet.org/forums/f...tid=243&threadid=48683
 08 October 2012 09:22 PM
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slittle

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In my book "stables" = agricultural building so section 7 applies and the incomer needs to be an rcd to comply for protection against fire etc.

Looks like Primo has this covered already so that's good.

As to the clippers, I spent many years clipping my horse with mains clippers without a problem. They are class 2 anyway so the only risk is if the horse stands on the cable and destroys the insulation with it's hooves.
This is easily prevented with a bit of common sense and cable management (nothing that can't be achieved with a bit of bale twine)

Stu
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