RCD omission risk assessment

[westward10]

The risk assessment isn't to decide whether additional rcd protection is or isn't required but to justify its omission.

 

[pc1966]

I understand that the supply cable from plug to machine will need to be made bigger and may well need some over current protection adding to the machine.

Why not a 32A plug with an in-line FCU?

But yes, the whole thing is a bit stupid. There are many cases when non-RCD sockets are needed or desirable and in locations where the risk is managed, having them labled ought to be the first step even if it is backed up by a risk assesment justifying why the are omitted and what steps (training, lables, extra bonding, shorter PAT testing times, etc) are in place to help mitigate the risk.

 

[pc1966]

But back to the OP's original question - are there any examples of how the RA should be done and documented?

 

[James]

Agreed, I would love to see a sample risk assessment.

 

[dodger421]

Agreed, I would love to see a sample risk assessment.

This was actually the reason I bought Codebreakers, Part 2 explains the process of risk assessing omission of RCD’s and gives some useful examples of the things to look for as well as a model form for this particular RA.

It’s not a complete example, but it gives a step for a hint in terms of likelihood and severity and the options the client has depending on the level of risk.

 

[pc1966]

Looks like I need to get a copy of the latest Codebreakers then!

In terms of 32A plugs and equipment not needing that much you can get stuff like this:
https://www.essentialsupplies.co.uk/power/adaptors/32a-adaptors/twin-13a-socket-32a-in.html

 

[Wilko]

what they are finding is that the rcd's are tripping when being used.

I would want to understand this aspect too. Is it normal for the 6A machine to have 30mA of leakage? Or is it that there’s several m/c on one circuit?

IIRC the PowersThatBe are looking to remove the RA exception from 18 Amd 2.

 

[Vortigern]

Maybe a monitoring device to detect what an RCD detects which then signals a relay alarm in the absence of RCD so that if there is the kind of fault the RCD would have detected then there would be an alarm/notification to key workers. i.e. mobile phone alert/audible alarm etc. Not so fantastic as Schneider do such a module that fits onto an existing MCB.

 

[Lister1987]

If you're omitting RCD protection, use sockets that are not standard 1363 ones, some come with a T shape pin, that way only modified equipment can be used, any attempt to circumvent this then puts the onus on the modifier (modifee?) and not the spark as they took methods to ensure a degree of protection (using nonstandard sockets/plugs)

 

[Strima]

If you're omitting RCD protection, use sockets that are not standard 1363 ones, some come with a T shape pin, that way only modified equipment can be used, any attempt to circumvent this then puts the onus on the modifier (modifee?) and not the spark as they took methods to ensure a degree of protection (using nonstandard sockets/plugs)

Look up the definition of a socket-outlet in the regulations, sadly you can't use this method to get around the problem.

 

[pc1966]

Non-standard plugs & sockets have some uses, e.g. to prevent arbitrary stuff being plugged in to protected supplies in hospitals, etc, but otherwise are a pain as they make testing stuff or using it in other locations a problem.

Sometime it seem BS/IET have their heads up there rears when it comes to issues like this. There are plenty of cases when a plug & socket is far more usable for high leakage current or critical equipment than having them hard-wired, so the apparent plan to drop the exemption completely seems crazy.

A perfect example is a data centre where is you have UPS with 16A or 32A commando feeding them then any of the usual technicians on duty at the time can swap thing in an emergency. Otherwise you have to get someone electrically qualified to rewire things who may not be available at 03:15 or whenever something is playing up. Also that makes supporting a generator easy if you have a modest planned outage, etc.

What is needed is much clearer guidance on how to manage exemptions, making clear when it is tolerable (e.g. factory equipment in dry areas, data centre, etc) and when it would be unacceptable (e.g. outdoors when water ingress is always a risk, and contact for anyone with the Earth much more likely) , as well as making it clear there must also be a technical justification for doing so (i.e. not because of RCD installation or on-going testing cost, etc).

 

[Elgreko]

I realise it’s a slightly older thread, however I’m looking for some help and advice regarding 3 phase sockets that were solely installed for welders in welding bays, they were fitted to interlocking sockets and are plugged in and left in, the only reason they were not hardwired is to allow for easy replacement on the production line if one breaks down, unfortunately they were not installed using rcd protection. However another company has since come in and told the client that essentially the equipment is dangerous as it doesn’t comply with BS7671, unfortunately the original designer of the installation has been let go and no risk assessment was prepared. I myself have never had much experience in the paperwork side of things as I’ve spent my life on the tools, any possible advice or help would be really appreciated. Thank you in advance.

 

[westward10]

What rating are these sockets and when were they installed.

 

[Elgreko]

What rating are these sockets and when were they installed.

They are 32 amp 3 phase N&E interlocking sockets and were installed last year, I’m well aware myself that BS7671 states that they need to be on rcds, however as reg 411.3.3 states that rcds can be omitted with a risk assessment. I’m guessing people are going to maybe come back and say they should be rcd protected, however what is the difference if the same piece of equipment was to be installed on a rotary isolator without rcd protection.

 

[westward10]

Hard wiring an appliance is certainly a way around this. A risk assessment should be carried out by the client if additional rcd protection is going to be omitted.

 

[Lister1987]

This is an rce risk assessment for our current design project, it's across 2 pages bit each line/row is a circuit.

 

[loz2754]

Hard wiring an appliance is certainly a way around this. A risk assessment should be carried out by the client if additional rcd protection is going to be omitted.

Agreed, but bear in mind Appendix 2 item 11, which states that "for the purposes of BS7671 a risk assessment should involve an appropriate electrically skilled person."

As has been said in this thread, it would be interesting to see an example of such a risk assessment.

 

[Elgreko]

Hard wiring an appliance is certainly a way around this. A risk assessment should be carried out by the client if additional rcd protection is going to be omitted.

Can I just ask what is the difference in the safety aspect if the same piece of equipment is hardwired, apart from the one time the plug is inserted then the inbuilt rotary isolator is turned on, everything else is exactly the same, the same piece of equipment will still be sat there with the same piece of wire connecting it to the isolator, all be it one has a plug and one doesn’t. Also does it have to be the client that has to produce the risk assessment or can it be an installer or designer that can produce the RA. Only ask as previous posters in this thread have mentioned they have added RA’s before.

 

[Lister1987]

Agreed, but bear in mind Appendix 2 item 11, which states that "for the purposes of BS7671 a risk assessment should involve an appropriate electrically skilled person."

As has been said in this thread, it would be interesting to see an example of such a risk assessment.

I've given an example just as you posted this ? it's from a design project

 

[loz2754]

They are 32 amp 3 phase N&E interlocking sockets and were installed last year, I’m well aware myself that BS7671 states that they need to be on rcds, however as reg 411.3.3 states that rcds can be omitted with a risk assessment. I’m guessing people are going to maybe come back and say they should be rcd protected, however what is the difference if the same piece of equipment was to be installed on a rotary isolator without rcd protection.

The difference is you have no control over what someone may plug into a socket outlet, whereas with fixed wiring you know exactly what it is supplying.