Hi Guys,
was curious at how many taps you can safely run on a single switched circuit, want to hook up my electric water pump but already have efans and intercooler pump off the one I know of (not sure if that is even cool). This particular one I have had already tapped would make the wire routing much neater.

Thanks

 

It all depends on the total current draw of all the attached equipment. If it exceeds the current rating of any of the wiring in the circuit, it will melt the coating , possibly causing a short with other wiring and eventually the wiring will fry. Also need to keep in mind the fuse rating for that circuit. Me personally, i would put something as important as the water pump on its own fused circuit.

 

What size is the wire ?

What size is the relay to power the times ?

How big is the fuse ?

What is the total AMP draw of everything ?

 

wire is 12 gauge

the relays are 30 amps for the fans and electric water pump not sure on the coolant pump, markings are pretty faded maybe 20 amps if that

fuse is 30 amps for the efans, 20 amps for the epump and 15 amps for coolant pump

amp draw is 9 amps per fan (2) at high speed and for the electric water pump 11-12, for the coolant pump for the intercooler I am thinking maybe 9 amps at the most.

 

The ampacity of a typical 12awg wire is 20-30 amps depending on the type of insulation the wire has. Exceeding the wires ampacity rating will break down the insulation over time and cause leakage and is also a major fire hazard. If you want to keep everything on the same circuit, I would suggest changing the feeder wire to an 8awg and fuse the circuits accordingly. Also make sure the switch you are running can handle that type of current draw. You most likely have a pretty significant voltage drop on that circuit as it is.

 

I would agree, you are at the edge of what you should have on that circuit with the current installed items.

More correct would be to have 10 AWG installed for Power and ground with that much, just to follow the 80% rule on load. This is not taking into account heat soak for the wire in the engine compartment.
The current items on the 12 AWG total 27 AMPs max. The e-fans ( and I would think both pumps more so ) will have some current inrush spikes when starting up. Heat soak can remove 30% of the amp load of the wire.

If the relays are to make the circuits hot in run position ( not to make the item itself run ) you should also change the relay out for a 40A version at least ( I usually go with 70 A relays once I need 12 or 10 AWG wire ).

If the wire is feeding power to the items, and the relays control them ( turn the e-fans on/off by a trigger like temp probe / controller ) then just upgrade the wire.

At a minimum you can add another 12 AWG, and have the new electric water pump on that circuit.
The wire type you are using will also have an impact. 90* C insulation has a much steeper drop off than 105*C wire at the engine compartment temps.

Think this is what you have ( and are looking at installing ), without the relay & fuse in the upper right hand corner. Correct me if I got that wrong.

 

Thanks for the help guys...much appreciated.

That diagram is what I have currently have minus the electric water pump, but was thinking of running before. I do have another switched circuit I found while waiting around for fedex to show up, I could use this for the electric pump. It is the one by the ecm, I know some tap that for their efans, so I was thinking maybe that this one would be sufficient.
Thanks.

 

A factory circuit ?

Wouldn't do that, but if you are talking about a trigger voltage, you can use any hot in run or run/accy position circuit.

Adding that much load to the factory wiring is not a good idea.

Maybe you should think about adding a fuse panel like the Centech or the Fuzeblock ?