wiring theory (how very interesting)

quick one for the electrically minded amoungst you... and sparky.

take 4 x55w spots and wire the relay correctly. now. if you connected the lives together and the earths to make a single wire (Each!) what would happen if you connected the earth to the relay and the aux end to an earth point...

...for argument sake.

this theory bears no resemblance to actual events which may/may not have occured in Bristol.

G

wtf is the aux end and if the relay wur wired correctly it would already be earthed

aux end is what im calling the wire from the bulbs. the earth is from each lamp cos they need to be earthed too

Griffdowg said:

what would happen if you connected the earth to the relay and the aux end to an earth point...
G

Click to expand...

instead of the aux end going to the relay (87) and earth to earth point.

G

sounds like you'd effectively short yer battery to earth through the relay terminals, resulting in a blown fuse (if fitted!) or melted wire / sparks and a buggered relay.

hmmm... interesting

anyone else?

Griffdowg said:

quick one for the electrically minded amoungst you... and sparky.

take 4 x55w spots and wire the relay correctly. now. if you connected the lives together and the earths to make a single wire (Each!) what would happen if you connected the earth to the relay and the aux end to an earth point...

aux end is what im calling the wire from the bulbs. the earth is from each lamp cos they need to be earthed too

G

Click to expand...

it depends - if the earth from the lamps is also connected to the metalwork and is therefore connected to ground at the attachment points. (the power must be isolated by definition).
by connecting the earth wires to power on the relay, you will have shorted 12v straight to ground which will have (in order of severity)

blown a fuse
blown the relay
melted wires
fooked the battery

any or all of the above are possible.

If, on the other hand, the earths from the lights are insulated from the metalwork, such that the earth wires are electrically "floating" - all you will have done is pass current backwards through the lights and as they are DC will have no effect at all.

ok.

well, i got a light pod which had 4spots allready wired up with 3 wires left. 2 together and 1 singular. so i took a look and a stab at what was what and it all worked apart from lamp #3. when i got up close they were emitting loads of heat and one of them even cracked the lens!

i was wondering if this senario could have caused this. something aint right though.

sorry Griffy - i think the best (and only) choice is to go back to square one and disconnect all the "attached" wiring and rewire each spot up one at a time into a multi way bullet connector block and check each one individually and then add them one at a time.

dont furget you are talking of 220W or over 18 amps! make sure all your wiring in the circuit will take that sort of current.

yer, thats what i thought... i was going to run 1 40amp relay, but now i think i will run 2 30a instead. what amp wire will i need? i did get some thick stuff the other day, but cant remember the rating.

im just a lazy youth

G

either 28/0.30 2mm^2 25Amp rated thinwall
or
44/0.30 3mm^2 33Amp thinwall shd do
preferred colour is Blue/Yellow