scraglor Posted August 25, 2008 Share Posted August 25, 2008 Some techno babble. The load from from a HID may be 400W but it the ballast produces a high Inductive not resistive load (most normal bulbs are simply resistive. The inductive load can be as high as 30 Amps and canweld a 13 Amp timer shut no it can't, a 400w will typically pull a start up current of up to around 3 times running current, so about 6 amps, maybe up to around 10-12A (if you have a piece of shit ballast and lamp) the fuse in your plug is rated at 13A and these are fast blow fuses for protection against shock, so anything over 13A would blow the fuse. but start up current generally isn't what welds contacts shut anyway (although if you overload the amperage rating of the timer this will of course happen), what welds them shut is the arcing that occurs when the contacts try to open, the magnetic forces of the arc hold the contacts together and the heat from the arc welds them Link to comment Share on other sites More sharing options...
scraglor Posted August 25, 2008 Share Posted August 25, 2008 Hi Assasin,IMO yes will be fine-just. Ohms law (remember your School Physics?) is Power=IV Watts (soppy aide memoire). Calc is for totally resistive load (formula transposed) 400W/240V=1.67Amps. Now for an inductive load this goes out of the window and a factor of about times 4 should be used. So 1500 W breaker you have = 1.67 (A) * 240 V *4 factor=1632W, so as i say a 1.5KW breaker just ok. Put a 10 Amp fuse on it just in case and this should blow if overloaded. Hope this helps-don't sue me if I'm all to cock sorry mate, but this aint how it works, a lot of digital timers are rated at well over 3kW and a 400w HID will weld em shut within a week, it's all down to mainly materials contacts are made of, distance between the contacts when they're opened, force of the spring that opens the contacts, number of breaks in the line by the breaking device.... etc etc. timers designed specifically for heaters are probably the worst, as they're designed purely for resistive loads, and thus the contacts are made from cheap materials not designed to withstand the arcing caused by inductive loads. resistive loads draw high start up currents also by the way, the start up currents drawn by HID's are due to the characteristics of the lamps, more than the inductive nature of the ballasts. a 3kw immersion heater will pull around 12A running current, but they still have a 30A fuse? this is because when the heater element is cold it has a much lower resistance than when it's hot,as you know from ohms law, lower resistance means higher current, hence why such a large fuse is needed even though the running current is nowhere near Link to comment Share on other sites More sharing options...
scraglor Posted August 25, 2008 Share Posted August 25, 2008 assasin, best thing to do mate is get a contactor, you may be lucky and your timer will last a long time, i had a good quality digi timer with a 30A relay inside and i ran my 400w for well over a year before it died, but it DID die eventually, thing is hid's kill timers, pretty much all timers, it's just a matter of when rather than if, a timer switching a contactor should last as long as your ballast Link to comment Share on other sites More sharing options...
dakter Posted October 6, 2008 Share Posted October 6, 2008 Just seen this on Maplins website the Q&a says inductive load is 13A is this too good to be true ?) Link to comment Share on other sites More sharing options...
hazedup Posted October 6, 2008 Share Posted October 6, 2008 Hi everyone having a couple of problems. We are soon to flower me Mazar but we seem to have a problem we are using a 250w H.I.D and it has already claimed the lives of two cheap Argos mechanical timers and funds don't stretch very far at the moment so i was wondering what timers do you guys use with your 250 watters?. I've heard that the Argos digital timers are able to work with a 250 but would like to hear some opinions. Thanks on my 2nd grow now and i use timers from tesco(4.99) with a 1000watter no problems as yet mate Link to comment Share on other sites More sharing options...
Guest dr rockster Posted October 6, 2008 Share Posted October 6, 2008 (edited) Timers without contactors are a fire hazard mate. You may well have had a problem free grow or 2 without contactors but its when you wake up and find your house on fire that you start to feel not quite so clever for trying to save a few quid. Don't faff about,just get a rated contactor and don't become part of the statistics on growroom fires because theres lots of them. Edited October 6, 2008 by dr rockster Link to comment Share on other sites More sharing options...
hazedup Posted October 6, 2008 Share Posted October 6, 2008 Timers without contactors are a fire hazard mate. You may well have had a problem free grow or 2 without contactors but its when you wake up and find your house on fire that you start to feel not quite so clever for trying to save a few quid. Don't faff about,just get a rated contactor and don't become part of the statistics on growroom fires because theres lots of them. not been tight just dont feel the need to fix something that isnt broken Link to comment Share on other sites More sharing options...
twigs Posted October 6, 2008 Share Posted October 6, 2008 Timers without contactors are a fire hazard mate. You may well have had a problem free grow or 2 without contactors but its when you wake up and find your house on fire that you start to feel not quite so clever for trying to save a few quid. Don't faff about,just get a rated contactor and don't become part of the statistics on growroom fires because theres lots of them. not been tight just dont feel the need to fix something that isnt broken good luck with that mate.. Link to comment Share on other sites More sharing options...
hazedup Posted October 6, 2008 Share Posted October 6, 2008 Timers without contactors are a fire hazard mate. You may well have had a problem free grow or 2 without contactors but its when you wake up and find your house on fire that you start to feel not quite so clever for trying to save a few quid. Don't faff about,just get a rated contactor and don't become part of the statistics on growroom fires because theres lots of them. not been tight just dont feel the need to fix something that isnt broken good luck with that mate.. shit chaps you have got me worried now think i may have to pop to my local diy store Link to comment Share on other sites More sharing options...
twigs Posted October 6, 2008 Share Posted October 6, 2008 Timers without contactors are a fire hazard mate. You may well have had a problem free grow or 2 without contactors but its when you wake up and find your house on fire that you start to feel not quite so clever for trying to save a few quid. Don't faff about,just get a rated contactor and don't become part of the statistics on growroom fires because theres lots of them. not been tight just dont feel the need to fix something that isnt broken good luck with that mate.. shit chaps you have got me worried now think i may have to pop to my local diy store good move...they sell fire extinguishers as well as contactors.. Link to comment Share on other sites More sharing options...
hazedup Posted October 6, 2008 Share Posted October 6, 2008 Timers without contactors are a fire hazard mate. You may well have had a problem free grow or 2 without contactors but its when you wake up and find your house on fire that you start to feel not quite so clever for trying to save a few quid. Don't faff about,just get a rated contactor and don't become part of the statistics on growroom fires because theres lots of them. not been tight just dont feel the need to fix something that isnt broken good luck with that mate.. shit chaps you have got me worried now think i may have to pop to my local diy store good move...they sell fire extinguishers as well as contactors.. funny guy but coincidentley i do have a fire extinguisher Link to comment Share on other sites More sharing options...
dakter Posted October 6, 2008 Share Posted October 6, 2008 (edited) Just seen this on Maplins website the Q&a says inductive load is 13A is this too good to be true ?) heheh sorry forgot to add the link . It seems too good to be true because if the inductive rating is 13 A wouldnt the resistive rating be more like 50-60 A . Thats huge for a timer ? heres the link http://www.maplin.co.uk/Module.aspx?ModuleNo=32997#features Edited October 6, 2008 by dakter Link to comment Share on other sites More sharing options...
dakter Posted October 6, 2008 Share Posted October 6, 2008 http://www.trgelec.co.uk This place is even better got the lot timer rated up to 4A inductive 15 quid cool Link to comment Share on other sites More sharing options...
The Happy Cropper Posted October 6, 2008 Share Posted October 6, 2008 Why wouldnt you buy a contactor? Playing with fire will get you burned, not a risk worth taking imho. Link to comment Share on other sites More sharing options...
Greenthumb_420 Posted October 6, 2008 Share Posted October 6, 2008 Why wouldnt you buy a contactor? Playing with fire will get you burned, not a risk worth taking imho. Fuckin' right. and i'm still buying 2 automatic fire extinguishers for when i'm out in work! one for inside my budbox and one for above the ballast, and that's a digital soft start 600W ballast and run through a relay contactor too! Don't piss about with fire risks people. Ganja for life eh! Not death (or prison) :wink: Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now