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Good morning, I have a query about public address system cabling. What is the maximum distance that a loudspeaker can be placed from the control panel using 100v speaker cabling? Thanks

Thanks for this. Am I correct that only one transformer/generator can be connected to the NER at the one time and this is achieved through disconnect switches and logic. Thanks

Hello, I have a question regarding the use of one Neutral Earthing Resistor per substation for two transformers. Can anyone point me in the direction of websites/ literature that would show the operational philosophy of this set up compared to one neutral earthing resistor per transformer...

Hello, With regards to 3 core 11kV cables run in parallel on a ladder that need to be jointed. is there a standard to say what the spacing should be between joints ? Thank you

Hi, I have a query in relation to MV fault levels for an 11kv switch board. How is the fault rating (x kA for x seconds) calculated from the following information: 3 phase fault Line to ground fault Line to line fault Line to line to found fault. For each of these scenarios we have I”k Ip...

Hello again, Does anyone know if there is a HD monitor available that can connect to the CCTV network Poe IP switch ( at a secondary location) so the cctv can be viewed at this second location. Thanks

Thank you for the replies.

Hi, I have a question about POE cctv systems tying into an existing site fibre network. I understand that a POE switch will be required for the cameras and also a Poe extender for camera distances greater than 100m from the switch but does anyone have an example architecture drawing to show how...

thank you for the replies.

Hello, Is it a requirement to have an earth switch fitted on 11kv fixed pattern switchgear as a contractor is saying an earth switch is only applicable to withdrawable switchgear. Thank you

Hi, With regards to bs7671 are there any rules regarding when to install a distribution board? For example say we have a main switch board that is feeding pieces equipment separately but these pieces of equipment are quite local to each other would it then be better to take one feed from the...

Thanks for the replies.

Hi, With regards to a Siemens DO card which has outputs rated 0.5A@24VDC if we are using these output channels to power 24VDC solenoid valves (0.3W &7w)would these require interposing relays as they are within the limits of the channel? Thanks

Thanks for the replies. Please see attached data sheet for a lamp which is24vDC. The data sheet has three connections I believe then that a 3 core cable should be provided but if this lamp is 24vdc then I am unsure as to why the earth is needed? Thanks...

Thanks for this.

Hello, I have a question regarding instrument cable. I know that for 4-20ma transmitters twisted pair cable should be used with the screen grounded at one end only. However for digital signals ( limit switches , push buttons ) can 2 core/ part of a multi core cable be used ? Thanks

Thanks for all the replies

Thanks for this. We have a drawing that shows a solenoid valve panel being powered from an adjacent control panel by 24vDc however this is shown as a 2 core cable connection but I was thinking it should maybe be a 3 core with the third core being an earth connection. Thanks

That’s great, thanks. Is this the same for all 24vDc circuits in that they only need a 2 core cable or are there occasions when a 3 core cable would be required with one core Earth. Thanks

Hello, I have a question about 24vDc powering instruments from a control panel. My question is why do we use a 2 core cable going to the device/instrument and do not provide a 3rd for for the earth connection like would be provided if the device was powered by AC single phase? Thanks