panel query regarding protection

[Monty2010]

I have received a panel built by someone else as part of a build I am carrying out. Unfortunately the customer has been involved in the selection of devices and wiring requirements however i feel there are a few things a miss.

The mains incomer comes in on a 63A 16mm 5 core SY, through an unfused isolator and into a 63A C rated breaker in 16mm singles, this then goes straight in to a 63A 300mA RCD on 16mm singles. out of the bottom of the RCD is 2 off 4mm singles per phase, 1 of the 4mm is the bus main for a row of breakers which are 2 off 6a, 2 off 16A, 1 off 20 and a 40A the three phases are split over these breakers, the other 4mm from the RCD makes its way to feed a number of contactors and daisy chains from each contactor, becoming the bus wiring.

My issue, surely each circuit should be protected sufficiently to the cable sizing used, so the bus wiring should really all be capable of with standing 63A as that is what it is rated at, or does the RCD change these requirements?

my other issue is the motors only have Overloads, which in my mind only provide overload protection to the motor and therefore the only circuit protection is the MCB 63A and the RCD 63A 300mA. however some motors are fairly small and 1.0mm2 cable has been used from the overload to the terminals in the bottom for me to wire the plant to.
this means that that 1.0mm cable has a 63A breaker protecting it? and a 63A rcd, surely this is not sufficient to rely on an RCD?

In my opinion the motor circuit cables will have to melt, touch earth and then allow the RCD to trip thus being insufficient protection.

I have spent sometime in my regs book but cannot find an actual requirement for overcurrent protection on motor circuits. i have found the statement in 552.1.1 which states every circuit should be capable of carrying FLA, is this enough in my defence to get this panel returned and fixed properly.

Monty

 

[netblindpaul]

I think he's referring to 9.4.3.1 (method c) but this is in respect to protection against maloperation due to earth faults, voltage interuption and loss of circuit continuity.

Where it brings up method C it mentions where the control circuit is not fed from a control TX so i think this is where the panel builder is confused as he thinks its a non restricted option and not guided by the conditions in 9.1.1.

PS Netblind... I have no issues with you I know you know your stuff and respect your comment whether or not I may agree fully or not, BTW regarding the fusing of my DC supply did you take a look at the link?.. Would the DC side in your opinion need external fusing as I have omitted it? The supply will be cut on OL or SC and won't re-establish without both re-power and no fault/OL conditions.

@Monty .. regardless of the panel builders excuses the fact that he taken it away to bring it more in line with regulations must be screaming out to you his competence... I still can believe the exposed incoming tabs so close to the cab case without room to lug up..that just says it all regardless of any other issues.

Im still unsure of the machine set-up but can't really believe this machine is hazard free and doesn't require some kind of E-stop circuit?

DW as far as the power supply goes.
I realise that you are not asking how to integrate the unit, and that your query is a compliance issue, and that I respect.
TBH, I don't know from the info given.
That sales blurb you linked to (not your fault) is just that IMHO.
I would be looking for some more detailed info before I accepted integration of that unit without secondary protection.
I did not see a mention of the standards it complied with, I would want to see the DOI for the unit, and see what directives & standards it complies with, to see what secondary protection it needed if any.

BTW, I only skimmed the link, so may have missed something.
Sorry if I have.

There may be a case of the blind leading the partially sighted here.
(Not you DW.)

 

[Darkwood]

Any progress with this panel Monty ..just wandering how things have progressed.

 

[LeeH]

This panel doesn't fall within the BS7671 it falls under BS60204-1 (General requirements for machinery control). Also other sub-sections of the BS60204 may be regulatory depending on what the panel controls.

BS7671 does have a few limited clauses regarding motor protection etc which mimic what is already in the BS60204.

Your Query about cable sizing is noted and what you have to take into account is this is not like a house rewire etc, many other protective measures can be used up or down stream of the main device. You will find that the majority of the time control panel loads have a fixed demand ... example the Incoming short circuit protection been covered by the MCB then the OL device on the contactor for a motor gives a fixed max limit of current that the cable could ever demand, this means the conventional fusing down isn't needed as such.

At the snippet of a pic you have posted my only comments are minor - lack of numbering on power cables, Power cables should all be black within the panel wiring and not in phase colours although BS60204 -1 (13.2.4) for colour coding is a recommendation where colour is used to identify the conductors use. As their is no other form of marking on his power cables he should have used all black.

BTW what is the panel doing?
Is their a safety relay - E-stop system (May not be required).
Blue conductors should all be clearly marked N and numbered as blue otherwise denotes DC control.
Are the socket outlets given 30mA rcd protection or are they covered by the 300mA you mentioned.. if 300mA what is the use ofthe sockets?

Your other queries ... the 1mm to the motors is adequate as the motor OL device protects them regardless of a RCD been in the set-up or not, depending on the make of wire the tri-rated 4mm will be rated approx 40-45amps so seems sufficient for the set-up ....again just a glimpsing observation as lack the info.

Judging by the lack on marking I can only guess no wiring plans and other relevant info has been supplied?

Lastly be careful of any critisism you do of the panel without knowledge of the relative regulations you will likely be shot down in flames ... I've been slated twice for similar reasons as your query and I arranged to meet the company boss with the Electrical contractor slating my work and tore him a new rectum hole .. he walked out with his tail between his legs and a caution that if i hear he has slated anymore of my work I will be sending my legal team to have a chat regarding defamation towords myself and business.... he kept well away from me the rest of the job.

Great post Darkwood you obviously know your onions. I just want to point out N should be Light blue, as 'normal' Blue denotes DC control as you have stated.

Gets the wholesalers ever time asking for a roll of 6mm light Blue Tri!

I never mark neutral as N as the colour denotes what it is. Does it actually state it should be? I've not come across that.

 

[LeeH]

The 1st thing i would be complaining about is all the cheap chint crap in there! sorry guys but it is the cheapest control gear on the market.
For me in an industrial enviroment where stuff gets a lot of work i would really want better quality parts in my panel.

I don't understand you issues with Chint, we use it if the customer has no preference.

I've never had a faulty component yet, the MCB's are Merlin, the push buttons and indicators are old style TM, the MMS's are old sprecher and schu etc.

 

[Darkwood]

Great post Darkwood you obviously know your onions. I just want to point out N should be Light blue, as 'normal' Blue denotes DC control as you have stated.

Gets the wholesalers ever time asking for a roll of 6mm light Blue Tri!

I never mark neutral as N as the colour denotes what it is. Does it actually state it should be? I've not come across that.

Yes I Stand correctly realised that the next day at work but clear indication of its use as a N can allow alternate colour code .. its preferable to do as you said though if your going to the T of the regs although anyone in a panel should be competent anyway regardless and understand the set up.

If my panel is inhouse im a little more relaxed on these things but if im selling it Im a stickler for the rules.

 

[D Skelton]

I never mark neutral as N as the colour denotes what it is. Does it actually state it should be? I've not come across that.

Reg 5.1 Lee. On the incoming supply conductor terminations, where a neutral conductor is used it shall be clearly indicated in the technical documentation of the machine, such as in the installation diagram and in the circuit diagram, and a separate insulated terminal, labelled N shall be provided for the neutral conductor.

BTW, it's threads like this that make forums what they are!

DW certainly does know his stuff, I will never grow tired of listening to what he has to say!

Great thread guys, certainly makes you look that little bit closer at the detail.