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Newbie needs relay help

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Gautam

Senior Benchmark Addict
Joined
Feb 4, 2003
Location
SF Bay Area
I got this relay from radioshack. It's wiring diagram looks like this:
relay.bmp

All relays that I've seen in articles and peoples' posts seemed to have 6 pins; mine has only 5. I I don't know what "Com" means but what I can gather so far is that I need to strip only one lead of the pump and connect one side to the normally open pin on the relay, and the other end to the "Com" pin. Then, of course, wire the molex leads to the coil. I'm supposing that powering the coil would end up connecting the cut lead of the pump if I wire it like this. However, I don't really know jack squat about wiring, so I'd greatly appreciate it if someone could tell me whether I'm on the right track or not. Thanks in advance.
 
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Diggrr

Underwater Senior Member
Joined
Nov 29, 2001
NO= normally open..power is off when coil is unpowered.
NC= normally closed..power is on when coil is unpowered.
COM= common..the other end of the switched wire.

Basically, carefully slice open the sheathing on your pump wire, and cut the white wire (some pumps use blue). Solder the two cut ends onto the NO and the COM leads.
A yellow and a black (any black) from the molex goes on the coil leads.

By the way, being that you bought this at Radio Shack and it looks nothing like mine, are you sure it's the correct power rating for your pump?
The coil should be 12volts, and the switched contacts should be 120volts at whatever amperage (greater than what your pump is).
The little black cube ones are usually for 12volt accessories like lights and amps and stuff in your car.
 
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OP
G

Gautam

Senior Benchmark Addict
Joined
Feb 4, 2003
Location
SF Bay Area
Thanks for your prompt reply. The contacts of my relay are rated at 10A @ 120 VAC, which I'm guessing should be more than enough to power my pump. The coil is rated at 12VDC with 30mA current. Actually, my relay looks just about the same as the blue one shown here, but it's wiring does seem to differ a bit.
 

Diggrr

Underwater Senior Member
Joined
Nov 29, 2001
I believe I've made one mistake in the instructions though, that should be the black wire cut and wired to the relay, as that is the hot wire. The white is neutral.

It will work fine either way really, but the relaying the black wire is safer from the standpoint of shorting something against the wire between the pump and the relay.
In most cases, you should be fine if I'm too late...
 

KlinKx

Member
Joined
Jun 1, 2002
Location
CT
Just to help clarify for any Newbie (speaking from experience); I bought the same relay from Radio Shack. I have a MaxiJet 1200 and wired it up as follows: Wired Yellow / Black from PSU (Molex connector) to the Coil leads. Since the MaxiJet is an AC pump, all I did was to slit the power cord in half lengthwise (only for an inch, about 1/3 away from pump) and cut one side. I wired the cut ends o NO and COM, as Diggrr stated. That's it. Not bad for $3.99.

{Edit} Of course, I insulated the leads as well.