Boost On indicator

RVG8tor · #1 12-06-2010, 05:00 PM

I want to wire a light that tell me I have the boost pump on. The plan is to have tow wires come off the out side of the switch, on to the pump and one to the light. The pump wire is #18, do I need to run #18 to the indicator light as well or can this be a smaller wire like #20 or #22.

I am not sure what happens with a short; will the CB pop before the smaller wire melts.

Thanks

Walt · #2 12-06-2010, 05:04 PM

22 is fine for the light. If you have an actual short in the wire the CB will pop.

jferraro17 · #3 12-06-2010, 06:27 PM

Mike,

I don't really have another solution for you, but doesn't this just tell you that the light is receiving power...not necessarily the pump? Flip the switch, light comes on, do you really know the pump is running?

I'm looking to do the same thing right now, and dismissed this way of wiring it as not meeting the intent of the indication.

Thinking out loud--
Joe

Walt · #4 12-06-2010, 06:35 PM

I have a light to remind me that the pump is on, true enough it doesn't actually tell you if the pump is working but the pressure gauge will do that for you.

I suppose if you wanted to add more "stuff" you could install a pressure switch on the pump output and wire it to a light... but seems like overkill to me

AltonD · #5 12-06-2010, 06:48 PM

Quote:

Originally Posted by Walt

I have a light to remind me that the pump is on. . .

I have the same thing. It works for me.

jferraro17 · #6 12-06-2010, 06:53 PM

I was trying to think of a way to tap the light wire off of the pump power wire somewhere down line of the switch...perhaps a small terminal block near the pump? More weight/stuff.

I don't know, the light and gauge are probably good enough...airplane, not a clock and all that

RVG8tor · #7 12-06-2010, 06:57 PM

Quote:

Originally Posted by jferraro17

Mike,

I don't really have another solution for you, but doesn't this just tell you that the light is receiving power...not necessarily the pump? Flip the switch, light comes on, do you really know the pump is running?

I'm looking to do the same thing right now, and dismissed this way of wiring it as not meeting the intent of the indication.

Thinking out loud--
Joe

Joe,

I am want the light as a reminder that the pump is on, it is not a pump function light. I could do the same with with a lighted switch which is what I have for my Pitot heat. I went that route just because I needed a switch with a different shape (too many toggles in a hard to reach area)

As some posted the pressure gauge will tell me if the pump is working, I just want something to help remind me the switch is in the on position so I don't fly for 2 hours with the pump on.

Back to lace tying wires

Greg Arehart · #8 12-06-2010, 07:13 PM

I just used a lighted rocker switch.

greg

Ironflight · #9 12-06-2010, 07:43 PM

My light is tapped off the power switch as well, and yup - it doesn't tell me that the pump is functioning, it tells me that the switch is on. But that's what I want it for. Fuel pressure tells me the pump is working - the light reminds me to turn the pump off (cause pressure doesn't stick out on the display...)

Paul

vlittle · #10 12-06-2010, 07:49 PM

Quote:

Originally Posted by Walt

22 is fine for the light. If you have an actual short in the wire the CB will pop.

The size of the wire is set by the circuit breaker/fuse rating according to AC 43.13 Section 4. The purpose of this wire sizing is to prevent fires. If you have a 10A breaker for the 18 AWG pump wiring, then the wire to the light needs to be 18 AWG.

If the lamp wire is in open air (not in a bundle) it is acceptable to use one size smaller gauge. In this case it would be 20 AWG.

If you have a 7A breaker, then you could use 22 AWG in open air.

Vern