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

 

[Clive P]

Hi,

To be honest I would be questioning this set up, but wait a while and see if Darkwood turns up; as he is your man when it comes to panels and controls.

Regards.

 

[Darkwood]

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.

 

[netblindpaul]

The panel is CE marked so don't worry, if it's not then send it back as it is not fit for purpose.
END OF as it is a Statutory Requirement.
BTW, DW is not far off, but it falls more correctly under the LVD, of which 60204 is one of the standards that you can use for compliance.

 

[Darkwood]

The panel is CE marked so don't worry, if it's not then send it back as it is not fit for purpose.
END OF as it is a Statutory Requirement.
BTW, DW is not far off, but it falls more correctly under the LVD, of which 60204 is one of the standards that you can use for compliance.

Good point and on that note the new harmonisation of the LVT with EU member states is out now which will be applicable from 2016 ... need to catch up with it at some point :uhoh2:

 

[Monty2010]

Panel function - Main electrical control and distribution for a mobile grain dresser.
fitted to rigid 17.5Ton truck, 60KVA Generator feeds the panel with a SY 5C16mm.

Im still not really happy with the panel, I have read some information relating to B EN 60204 and the way I understand it, each motor circuit should be protected for overcurrent of the contactor rating. for instance one of the biggest contactors is 32A rated, therefore I see it that it isn't protected for that particular contactor as it is only protected by the 63A MCB and RCD. I have knocked a quick drawing up of the panel as it is wired could you glance over it and give me your feedback.

this is just an additional issue I have with the panel, the panel was delivered with the isolator exposed incoming terminals 1/2 inch clear of the bottom of the enclosure, isolator operating handle an inch too short, no shrouds for exposed isolator parts, outgoing connection terminals only rated at 24A, ok on most but not all, and only crimping the boot lace crimps on the very tip due to how narrow they were. due to all these reasons I have picked further and this is what leads me to believe the wiring may be at fault also.

 

[netblindpaul]

That panel does not comply with 60204.

 

[Monty2010]

net blind paul, can you give me a little more on that please, I have been asked to evaluate its suitability, which at the moment I have stated, its not fit for purpose in my opinion, I could just do with a bit of meat why.

 

[netblindpaul]

Look at 60204-1 & see what the standard says about control voltages & colour coding as a start.
I can see no control transformer with primary and secondary protection as a start.

 

[Darkwood]

Have to agree with you on the interlock switch its too close to the base, no room for your incoming lugs and is exposed and dangerous to anyone opening the panel without upstream isolation.

Im scratching my head at the sheer number of relays here although I don't have the wiring plans I think the guy who did this is old school and is many years behind technology this is crying out for a PLC to get rid of the bulk of those relays.

The box is over crowded too no allowance for maintenance, repair or additions where the new parts may require more room in some cases.



Here's my last weeks project ...it was in-house and i had to re-use existing star/delta contactors and to the keen eyed ive made a few excursions from the BS60204 but nothing of safety issue.

 

[netblindpaul]

I can't see any circuit protection on the RS dc power supply, if that is what it is as you are using blue singles.
For the price of 2 off 2 pole MCB's why not, when it is stipulated?
Also the red power cores in the top RH corner.
Else, I can't see anything that I would be overly concerned about in a 30 second look at the pic.

 

[Monty2010]

The relays are due to the guy wanting to run the plant manually? he talked the company in to it for some reason. that's also an issue that I have to pull up with him tomorrow as his relays switch out safety functions and allow the plant to choke.is it not permissible to use a 240V control circuit? or I it ok when used with a 30mA RCD?Where's the cheapest place to buy the 60204 in pdf tonight, mine are at work and could do with a read up now at home.

 

[Darkwood]

I can't see any circuit protection on the RS dc power supply, if that is what it is as you are using blue singles.
For the price of 2 off 2 pole MCB's why not, when it is stipulated?
Also the red power cores in the top RH corner.
Else, I can't see anything that I would be overly concerned about in a 30 second look at the pic.

You not seen the MCB's at the top L/H corner? these cover primary of the dc power supply 1p+n and the 3pole is the protection for the star/delta set-up its 400v coils tapped of the incoming to the contactors.

The dc side of the power supply unit is internally O/L protected and S/C protected, no need for external fusing on the dc controls.

 

[netblindpaul]

This panel must meet the LVD.
One of the applicable A, B & C standards is 60204.
To be honest if you are putting together a professional engineering report on this then you need to have copies of the LVD & all of the relevant standards.
If this goes to civil or criminal court, without these you will be made into mincemeat.
You really need to consider your role in this carefully.
Also, it seems that it is a case of the blind leading the partially sighted.
The specifier was blind and the builder was partially sighted!
Look in 60204 & you will see the requirement for control circuit supplies.

 

[Monty2010]

pulling back round to the original question, should there be over current protection, at least a fuse preferably an MCB in line with each motor circuit t protect the cable and contactor from overcurrent an short circuit fault. 63A rated cable from the bottom of the rcd, preferably feeing a rated bus bar connector in the top of the contactors and breakers.

 

[Darkwood]

The relays are due to the guy wanting to run the plant manually? he talked the company in to it for some reason. that's also an issue that I have to pull up with him tomorrow as his relays switch out safety functions and allow the plant to choke.is it not permissible to use a 240V control circuit? or I it ok when used with a 30mA RCD?Where's the cheapest place to buy the 60204 in pdf tonight, mine are at work and could do with a read up now at home.

Where are all the controls on the front door or any remote of the panel?
If the control is 230v where is the isolating transformer? ....

you original question is no the OL of the motors protects the cables from overload its just done downstream rather than upstream ... like netblind says if it aint EC marked and supplied with the relevant documents don't accept it, the more i look at it the more i see and the more i believe its a old hat probably mature sparks / engineer that has not keep up with times.

Regarding my plc comment his reason for so many relays is a fob off it has no bearing on manual control and you already highlight control issues anyway.

Is there a risk element to the user of this machine ... would their be a need for a E stop in your mind?

 

[netblindpaul]

You not seen the MCB's at the top L/H corner? these cover primary of the dc power supply 1p+n and the 3pole is the protection for the star/delta set-up its 400v coils tapped of the incoming to the contactors.

The dc side of the power supply unit is internally O/L protected and S/C protected, no need for external fusing on the dc controls.

Yes I saw MCB's top LH corner, but these are power MCB's black in black out.
Once the wiring leaves the MCB to supply a control circuit, it becomes a control circuit, thus, is is no longer a power circuit?...
Personally I don't believe that the dc side complies without fusing/mcb protection as I can't see what the details of the power supply, so until I do, I have to say it requires protection don't I!

 

[Darkwood]

Yes I saw MCB's top LH corner, but these are power MCB's black in black out.
Once the wiring leaves the MCB to supply a control circuit, it becomes a control circuit, thus, is is no longer a power circuit?...
Personally I don't believe that the dc side complies without fusing/mcb protection as I can't see what the details of the power supply, so until I do, I have to say it requires protection don't I!

http://docs-europe.electrocomponents.com/webdocs/0add/0900766b80addf4e.pdf

 

[Monty2010]

Where are all the controls on the front door or any remote of the panel?
If the control is 230v where is the isolating transformer? ....

you original question is no the OL of the motors protects the cables from overload its just done downstream rather than upstream ... like netblind says if it aint EC marked and supplied with the relevant documents don't accept it, the more i look at it the more i see and the more i believe its a old hat probably mature sparks / engineer that has not keep up with times.

Regarding my plc comment his reason for so many relays is a fob off it has no bearing on manual control and you already highlight control issues anyway.

Is there a risk element to the user of this machine ... would their be a need for a E stop in your mind?

Controls all on front door, except a remote switch for forward/reverse of an auger
There is no isolating TX
E stop circuit feeds first relay, which then feeds control circuit from there.
The spark is about 35, he strikes me as domestic turned panel builder.

 

[Monty2010]

Where are all the controls on the front door or any remote of the panel?If the control is 230v where is the isolating transformer? .... you original question is no the OL of the motors protects the cables from overload its just done downstream rather than upstream ... like netblind says if it aint EC marked and supplied with the relevant documents don't accept it, the more i look at it the more i see and the more i believe its a old hat probably mature sparks / engineer that has not keep up with times.Regarding my plc comment his reason for so many relays is a fob off it has no bearing on manual control and you already highlight control issues anyway.Is there a risk element to the user of this machine ... would their be a need for a E stop in your mind?

Controls all on front door, except a remote switch for forward/reverse of an augerThere is no isolating TXE stop circuit feeds first relay, which then feeds control circuit from there.The spark is about 35, he strikes me as domestic turned panel builder.