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Low Voltage Distribution at Home
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19-03-2014 2:55pm#1
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Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,594 Mod ✭✭✭✭
Join Date:Posts: 12292
Hi OP, I have had a good think about this.
I take it all back
Apart from the 230VAC supply I imagine that you would be permitted to run and terminate the cabling you describe. Why? Because alarm installers, satellite installers and network point installers do not have to be registered electrical contractors.0 -
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Battery powered and wireless any use ? bit safer than running LV everywhere
I'm not completely against wireless but when wired is available i'll go with it. I'll be building this system myself (i'm an electronic engineer) and want complete control over everything. Anyway i'll need to power the sensor nodes too.Would you not just save yourself the headache and get some POE adapters / injectors?
http://www.ebay.co.uk/itm/48V-24V-AC-Adapter-Supply-For-PASSIVE-PoE-Box-Power-Over-Ethernet-Injector-Kit-/121221202679?pt=LH_DefaultDomain_0&var=&hash=item1c3958c2f7
or even a POE switch : http://www.ebay.co.uk/itm/NETGEAR-8-port-10-100Mbps-ProSafe-Switch-with-POE-FS108P-/301112143706?pt=UK_Computing_NetworkSwitches_RL&hash=item461baeaf5a
I'm not using ethernet, i'll be using rs485 serial. As far as i recall PoE works by biasing the data lines and even if i could make it work it doesn't seem to actually solve any issueHi OP, I have had a good think about this.
I take it all back
Apart from the 230VAC supply I imagine that you would be permitted to run and terminate the cabling you describe. Why? Because alarm installers, satellite installers and network point installers do not have to be registered electrical contractors.
Well this is good news then! Alarms are mostly (all?) 24v aren't they?jeepers101 wrote: »Would that not fall under minor works?
I had to google that term, it seems the comment i made about "anything not plugged into a socket" is wrong. It looks like adding a transformer or SMPS into an existing circuit would be allowed. I wouldn't mind if i needed to get this done anyway - once i have freedom to work on the LV side0 -
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Hopefully!
I am just giving an opinion.
Generally alarms are 12VDC
"Minor works" do not have to be carried by a registered electrical contractor and are defined in the Restricted Works link above.
Yeah but your opinion suits me so i'll take it as fact
It gives a couple of examples of 'minor works' which are far beyond what i would need to do. Although it might give me more scope for converting the 230v supply locally and direct to whatever voltage i need rather than sending this intermediate source from a central location0 -
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Is there not an argument in there about the length of time in contact though?No, the 110v direct. 55v barely perceivable on hands, if at all. 110v is perceivable, but very mild.
Again, most assume 110v = decent shock. It wont, unless there is a very good contact area, wet hands, etc, and even then it wont approach anything like what 230v will inflict in the same circumstances.
Say a 110V supply came in contact to the skin and (as you say) the person barely perceived it (if they were drunk or something ) and it remained in contact. I think a low current flowing, caused by 110V contact, over time will eventually lead to serious harm to tissue and the nervous system.
It's a rather theoretical argument, but I think it's the logic behind the 50V number.0 -
Is there not an argument in there about the length of time in contact though?
Say a 110V supply came in contact to the skin and (as you say) the person barely perceived it (if they were drunk or something ) and it remained in contact. I think a low current flowing, caused by 110V contact, over time will eventually lead to serious harm to tissue and the nervous system.
It's a rather theoretical argument, but I think it's the logic behind the 50V number.
Not all theoretical. Got 110v before, ammeter, you can work out the rest yourself. Couldnt get it to read above 10ma even with wet hands as far as I remember. All in the name of science:)
It was perceivable, but very mild.
The 50v number is just a voltage they deem safe. There are other hazards to a given voltage besides direct shock hazard, but its likely it is purely on that basis that it is the level picked. Id guess the people who decide these things would have the same assumptions as most when it comes to electrical shocks at given voltages.0 -
To you yes, with your big, leathery, old man handsNot all theoretical. Got 110v before, ammeter, you can work out the rest yourself. Couldnt get it to read above 10ma even with wet hands as far as I remember. All in the name of science:)
It was perceivable, but very mild.
I would imagine a small child would probably perceive more than that. And a shock directly across the chest. And domestic pets, etc would have different body resistances.
There's a table I remember being taught that gave the current readings a body could take and the damage inflicted over different time scales of exposure to the current flowing. I forget the figure now though.0 -
To you yes, with your big, leathery, old man hands
No leathery hands here. Small hands that look like they never did any work. There was added water as well.
A 12v battery terminal in each hand would have current flowing across the chest too. A child might be more at risk from a given current level, but unlikely to receive any more of a dangerous shock from 110 volts than anyone else.I would imagine a small child would probably perceive more than that. And a shock directly across the chest.
Hard for them to have a 110v line in each hand though:pac:And domestic pets, etc would have different body resistances.
Water is a toxin at a certain amount taken, actually acts as a toxin. Takes a fair bit of effort to bring it to effect though.There's a table I remember being taught that gave the current readings a body could take and the damage inflicted over different time scales of exposure to the current flowing. I forget the figure now though.
And alcohol, over 2 units a day and damage is done. Thats the way it goes though.0 -
To you yes, with your big, leathery, old man hands
I would imagine a small child would probably perceive more than that. And a shock directly across the chest. And domestic pets, etc would have different body resistances.
There's a table I remember being taught that gave the current readings a body could take and the damage inflicted over different time scales of exposure to the current flowing. I forget the figure now though.
Some thing along these lines, https://www.osha.gov/SLTC/etools/construction/electrical_incidents/eleccurrent.html0 -
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