P
Paul.M
The warehouse manager asked me to make up a 50 meter extension lead for his pressure jet wash machine to be used to clean the path leading to the showroom entrance, car park and the lorries. The pressure washer will use a max of 13A and will be plugged into a Blue 230V commando outlet which is protected by a 16A MCB, commando socket is wired in 4mm singles in galv conduit about 4m from the DB so volt drop/cable size/MCB is not a problem and it is on its own circuit. (more info than what is needed but I'm painting a picture for you lol).
Q:- What type of cable would you used and why?
A:- 3183Y Blue Arctic cable, 3 core PVC. A 3 core mains cable with special core insulation / sheath which allows the cable to remain flexible at temperatures as low as -20°C. Ideal for use with tools or equipment used outdoors or in a cold environment.
Current Rating: 25 Amps
Conductor Flexible annealed copper
Insulation: Arctic grade PVC
Sheath: Arctic grade PVC
Q:- What CSA of cable would you use and why?
A:- 2.5mm due to the machines current requirement (start up current about 10A, running current less than 5A). Over a distance of 50m we need to think about Volt Drop (VD) and disconnection times of the OCP (MCB/RCBO etc). VD for this type and size of cable is mV/A/M: 19. I did not want to go into too much detail on this due to other things that effect the calculations that will be too much for some trainees, Never intended this to be a lecture, just a bit of fun away from normal collage questions and the like.
Q:- Is it necessary to provide rcd/rcbo protection in this situation?
A:- In a nutshell NO!!!
BS7671 Reg 411.3.3 states:- An exception to (i) is permitted for:-
(a) socket-outlets for the use under the supervision of a skilled or instructed persons, e.g. in some commercial or industrial locations, or
(b) a specific labelled or otherwise suitably identified socket-outlet provided for connection of a particular item of equipment.
Also due to this being a pressure washer with a good start up current Reg 314.1 (iv) comes into play:-
Every installation shall be divided into circuits, as necessary, to:
(iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced by equipment in normal operation.
Of course we would want it on an RCD/RCBO due to this being for out door use + water! You have to look at the situation and do a risk assessment. Look at the proposed use of the socket and extension lead, who is going to use it, what for and where? Do you think it is safe and could you stand up in a Court of Law to defend yourself if anything went wrong?
The warehouse manager knows what he is doing and I have instructed him about the use of the socket outlet and the extension lead. Check the lead for any damage before use. Check both plug and socket for damage. Only use when the weather conditions are suitable etc.
Now that was a long answer to a short question lol. Need to think up another one.
Q:- What type of cable would you used and why?
A:- 3183Y Blue Arctic cable, 3 core PVC. A 3 core mains cable with special core insulation / sheath which allows the cable to remain flexible at temperatures as low as -20°C. Ideal for use with tools or equipment used outdoors or in a cold environment.
Current Rating: 25 Amps
Conductor Flexible annealed copper
Insulation: Arctic grade PVC
Sheath: Arctic grade PVC
Q:- What CSA of cable would you use and why?
A:- 2.5mm due to the machines current requirement (start up current about 10A, running current less than 5A). Over a distance of 50m we need to think about Volt Drop (VD) and disconnection times of the OCP (MCB/RCBO etc). VD for this type and size of cable is mV/A/M: 19. I did not want to go into too much detail on this due to other things that effect the calculations that will be too much for some trainees, Never intended this to be a lecture, just a bit of fun away from normal collage questions and the like.
Q:- Is it necessary to provide rcd/rcbo protection in this situation?
A:- In a nutshell NO!!!
BS7671 Reg 411.3.3 states:- An exception to (i) is permitted for:-
(a) socket-outlets for the use under the supervision of a skilled or instructed persons, e.g. in some commercial or industrial locations, or
(b) a specific labelled or otherwise suitably identified socket-outlet provided for connection of a particular item of equipment.
Also due to this being a pressure washer with a good start up current Reg 314.1 (iv) comes into play:-
Every installation shall be divided into circuits, as necessary, to:
(iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced by equipment in normal operation.
Of course we would want it on an RCD/RCBO due to this being for out door use + water! You have to look at the situation and do a risk assessment. Look at the proposed use of the socket and extension lead, who is going to use it, what for and where? Do you think it is safe and could you stand up in a Court of Law to defend yourself if anything went wrong?
The warehouse manager knows what he is doing and I have instructed him about the use of the socket outlet and the extension lead. Check the lead for any damage before use. Check both plug and socket for damage. Only use when the weather conditions are suitable etc.
Now that was a long answer to a short question lol. Need to think up another one.
