Connecting relay to a 10mm2 cable

[De.windhoos]

I'm in the process of rewiring my boat. Today I discovered that the cable to my Jabsco Macerator pump is way too small. According to the manual I need to use 10mm2 cables. My switch panel cannot handle that size cable.

So my thinking is to run a cable from the main busbar and use a standard mini relay to switch the pump on/off.
I'm now stuck on how to attach a 10mm2 cable to the relevant poles on a relay. The pump uses 15A and requires a 20A fuse. To my knowledge, female spade terminals can handle up to 6mm2 cable. So I need some kind of socket where I can plug the relay in and can handle 10mm cables using ring terminals.

 

[superheat6k]

The 10mm2 cable is likely to reduce volts drop when the macerator is running, in which case simply reduce to 4mm2 near the connection point. I would join these with a straight 16mm2 coupler and hydraulic crimping tool. Cover the joint with shrink wrap a couple of inches either side.

 

[sutton sailor]

I expect they specify 10mm cable so that the volt drop is not high. I f you reduce the number of strands in the 10mm cable so that it is the equivalent of 6mm for the last few millimeters of the cable run, the 10mm cable will now fit .

 

[lask]

In the same way works my own without voltage drop (volts) 10mm cable with a length of about 8 meters a few years

 

[Daverw]

Instead of a relay use a small contactor, these have larger terminals

 

[Moodysailor]

Can you not use a larger (e.g 40A) relay with larger terminals? The maximum current rating of the relay/contactor (you could even use a starter solenoid...) won't matter.

A quick flick on Amazon showed a solenoid, if it is mounted in the dry this should be OK, and at that price it's cheap enough to buy a spare...

Sidougeri Continuous Duty Solenoid Relay Switch 200Amp Winch Golf Cart 12V Heavy Duty: Amazon.co.uk: Car & Motorbike

 

[VicS]

I'm in the process of rewiring my boat. Today I discovered that the cable to my Jabsco Macerator pump is way too small. According to the manual I need to use 10mm2 cables. My switch panel cannot handle that size cable.

So my thinking is to run a cable from the main busbar and use a standard mini relay to switch the pump on/off.
I'm now stuck on how to attach a 10mm2 cable to the relevant poles on a relay. The pump uses 15A and requires a 20A fuse. To my knowledge, female spade terminals can handle up to 6mm2 cable. So I need some kind of socket where I can plug the relay in and can handle 10mm cables using ring terminals.

A Heavy duty relay, with 6mm stud terminals, must surely be the answer

eg 12V 200A 4 Pin Normally Open Relay

and 10 mm² to 6mm terminals on the wiring

eg 10-6mm Copper Tube Terminals

 

[rogerthebodger]

If you get a relay with screw tab terminals you can use an uninsulated copper terminal for the size of cable (10 mmsq) and a hole to suit the screw in the tab .terminal

Copper Tube Crimp Terminals 4mm 5mm 6mm 8mm 10mm 12mm 14mm 16mm 20mm Hole sizes | eBay

Heavy Duty 12v DC Relay 200a Automotive Switch for sale online | eBay

Maybe the same a VicS posted as I cannot get to VicS link

 

[PaulRainbow]

I'm in the process of rewiring my boat. Today I discovered that the cable to my Jabsco Macerator pump is way too small. According to the manual I need to use 10mm2 cables. My switch panel cannot handle that size cable.

So my thinking is to run a cable from the main busbar and use a standard mini relay to switch the pump on/off.
I'm now stuck on how to attach a 10mm2 cable to the relevant poles on a relay. The pump uses 15A and requires a 20A fuse. To my knowledge, female spade terminals can handle up to 6mm2 cable. So I need some kind of socket where I can plug the relay in and can handle 10mm cables using ring terminals.

As a couple of others have said, the reason for 10mm cable is to combat voltage drop, as far as the required current is concerned you could use 2.5mm cable, but the voltage drop would be too great. Adding a relay is not only pointless, but it over complicates things and just adds more things to go wrong. I would follow the suggestion in post #2 and simply splice a short length of 6mm (or even 4mm) cable to the 10mm cable, at the panel end. This is not a bodge, it's a perfectly acceptable method.

 

[VicS]

I'm in the process of rewiring my boat.

A Heavy duty relay, with 6mm stud terminals, must surely be the answer

The alternative is to use a momentary on 20 amp switch or push button without a relay .... Furneaux Riddall ( who are the "go to suppliers " in the Portsmouth and wider Solent area) offer a nice looking 20 amp stainless steel button but you will probably have the same problem connecting your 10mm² cable to a 20 amp switch as you do to a mini relay

The heavy duty relay with stud terminals offers a good , sound engineering solution. It will probably outlast the Jabsco pump so any suggestion that it is something else that will go wrong is total nonsense.

 

[PaulRainbow]

The alternative is to use a momentary on 20 amp switch or push button without a relay .... Furneaux Riddall ( who are the "go to suppliers " in the Portsmouth and wider Solent area) offer a nice looking 20 amp stainless steel button but you will probably have the same problem connecting your 10mm² cable to a 20 amp switch as you do to a mini relay

How is this an alternative to being unable to fit 10mm cable to his distribution panel ? He no doubt already has a momentary switch/button, but that will be located in the heads, near the toilet i imagine. The Op was asking about making the connections at his panel. Besides, 20a switches and buttons don't usually have terminals for 10mm cable. The pump will already be fitted with cable tails (Jabsco usually use 2.5mm cables on this size of pump), so he'll have to splice the 10mm cable at the heads end anyway.

The heavy duty relay with stud terminals offers a good , sound engineering solution. It will probably outlast the Jabsco pump so any suggestion that it is something else that will go wrong is total nonsense.

I actually said "just adds more things to go wrong".

I didn't say it will go wrong, although it no doubt will eventually. There is also additional wiring, additional connections additional fusing, all of which could fail.

All that's needed is a simple spliced tail on the 10mm cable. This is a tried and tested/approved method for solving issues such a this, where the heavier cable is only required to combat voltage drop.

If high current loads need to be switched with low amperage switches, such as remote battery switching, or starter motor solenoids, etc, a relay would be appropriate. In the OPs case, it isn't needed.

You're just trying to create a solution for a problem that doesn't exist.