how many amps?

[gpz900jim]

I know this is a really daft question, so please dont shout at me but I cant work it out. I have 5 x 50 watt 12 volt bulbs powered by a 230 volt to 12 volt transformer. Could someone kindly tell me how many amps they use??? Thanks

 

[rocker]

When working this out using power law, take the wattage of the lamps but the voltage from the beginning of the transformer coil i.e. 230V.

 

[telectrix]

250 watts at 12 volt. P=IV therefore I=P/v. I = 250/12 = 23.8A. ssssssimple. must be a bllody big transformer!

your amps at 230v would be just over 1A

 

[nickblake]

Basically ohms law V =I/R = 250 watt / 230 = 1.09 amps

 

[telectrix]

Basically ohms law V =I/R = 250 watt / 230 = 1.09 amps

i couln't be ***** getting up for the abacus to work that one out. just spotted that one nick. have you got a different ohms law in wales???????

 

[rocker]

i couln't be arsed getting up for the abacus to work that one out. just spotted that one nick. have you got a different ohms law in wales???????

I can confirm we do not. I'm sure he was thinking of power law.

 

[Steve1412]

250 watts at 12 volt. P=IV therefore I=P/v. I = 250/12 = 23.8A. ssssssimple. must be a bllody big transformer!

your amps at 230v would be just over 1A

You using your estimating calculator matey!!!!!!!

 

[Marvo]

250 watt / 230 = 1.09 amps

You could then divide the answer by the efficiency especially if using inductive transformers.

Basically ohms law V =I/R

This must be the new Ohms Law taking into account climate change perameters....

 

[telectrix]

aren't all transformers inductive, or have they invented a micro chip that can supply 30A@12V . nano technology?

 

[telectrix]

You using your estimating calculator matey!!!!!!!

got up for the calculator once. enough is enough. have to admit, i'm old school. when i did my learning bit, the most advanced calculator was a slip stick ( those of us lucky enough had one with HP-KW bit on them. the only thing digital was a red led watch and they cost £100. that was a months wages then.

 

[nickblake]

Opps ...lol look ive spent the afternoon out side in the pooring rain up to my knees in mud jointing a 25mm armour some numpty cut through with a JCB , yes rocker it should have been power law , answer was right though lol so it should have read I= P/V

 

[Steve1412]

Most exciting thing I could do with a calculator is write ******** when u turned it upside down..lol

 

[telectrix]

Most exciting thing I could do with a calculator is write ******** when u turned it upside down..lol

well, what would you expect from Hull. wasn't it somewhere there they hanged a monkey as a spy?

 

[mbga9pgf]

The answer is 20.8 Amps.

This is why ELV lighting needs either heavy duty cable, or alternatively, one transformer per lamp to minimise cable runs. Dont do what the numpty did at our house which was have 8m runs of 1.5mm from a single tranny and wonder why the lights looked if they were on a dimmer.

We installed 11 50w downlighters and each had its own transformer.

Does the lamps no good either if you know about tungsten filament bulbs not working at their rated power.

 

[telectrix]

250/12 does not equal 20.8. its 23.8

 

[mbga9pgf]

Nice wind up. Wonkey slide rule?

 

[telectrix]

you could always use a 230/110 v site transformer, series /parallel the 12v halogens.

 

[telectrix]

Nice wind up. Wonkey slide rule?

nah, used one of those new fangled digital calculator machines. could be iffy though, my bank manager gave it to me.

 

[gpz900jim]

Once again, thanks very much, it was the transformer that was confusing me, i didnt know what effect it would have on the calculation, but now its explained, i can will be ok for ever more. (in that bit anyway!!)

 

[telectrix]

rule no.1. 1 12v halogen lamp- 1 60VA transformer. 2 lamps- 2 transformers. etc.etc. bad practice to fit more than one lamp to a tranny. like putting all your eggs in one womb. oops, basket.