Wire choice for float and bilge pump

[fionn1432]

Hi all
I'm planning to wire up a bilge pump and float switch they are both separate. They will be wired into a sea flo 3 way bilge pump switch. I have 14awg 12v 20amp cable. Would this cable be suitable for what I'm planning to do

Thanks

 

[Slowboat35]

I'd have thought tinned cable would be all but essential for wiring to a bilge pump. It really should be used in all marine applications.
As for the amperage rating, the minimum is dictated by the current draw of the pump which we don't know. While undersizing cable isn't wise overspecifying that rating substantially has no benefit whatsoever but increases cable costs - though that probably aren't a consideration here.
For instance, Seaflo make a 1100gph pump which draws max 6 amps (probably momentary starting current) and suggest it is fused at 5a. A very pessimistic 6a at 12v as you know is 72watts. Your 20a cable is rated to draw 240w and that'll have a decent mnargin built in. Thus even this big pump draws only about a quarter of the capacity of your wire so unless your pump is unusually big or you plan to run four off the same cable it will be more than well able to cope.

 

[Alex_Blackwood]

Hi all
I'm planning to wire up a bilge pump and float switch they are both separate. They will be wired into a sea flo 3 way bilge pump switch. I have 14awg 12v 20amp cable. Would this cable be suitable for what I'm planning to do

Thanks View attachment 177782

Simple answer is, Yes. More than adequate for that 14 AWG is 2.5mm cross Sectional Area (CSA) 16 AWG is 1.5 and would also be suitable for a bilge pump.
All that is assuming you have reasonably short runs and little or no volt drop. The purists will be along to explain it all

 

[fionn1432]

I'd have thought tinned cable would be all but essential for wiring to a bilge pump. It really should be used in all marine applications.
As for the amperage rating, the minimum is dictated by the current draw of the pump which we don't know. While undersizing cable isn't wise overspecifying that rating substantially has no benefit whatsoever but increases cable costs - though that probably aren't a consideration here.
For instance, Seaflo make a 1100gph pump which draws max 6 amps (probably momentary starting current) and suggest it is fused at 5a. A very pessimistic 6a at 12v as you know is 72watts. Your 20a cable is rated to draw 240w and that'll have a decent mnargin built in. Thus even this big pump draws only about a quarter of the capacity of your wire so unless your pump is unusually big or you plan to run four off the same cable it will be more than well able to cope.

It's tinned

 

[Boater Sam]

Are the terminals large enough? 1mmsq cable would be sufficient if the run is not over say 8m.

 

[fionn1432]

Are the terminals large enough? 1mmsq cable would be sufficient if the run is not over say 8m.

About 4 or 5 meters maybe less the terminals are fine. Do you reckon I put a 5amp fuse on as well or would the seaflo trip switch just do

 

[fionn1432]

Simple answer is, Yes. More than adequate for that 14 AWG is 2.5mm cross Sectional Area (CSA) 16 AWG is 1.5 and would also be suitable for a bilge pump.
All that is assuming you have reasonably short runs and little or no volt drop. The purists will be along to explain it all

Maybe 4 or 5 meters or less

 

[ChromeDome]

Purist? Arh... not been accused of that before. Like in ever.

The pump consumption (Amps - not water), the wire length and potential physical impact would be part of my considerations.

Unless the wires are really long, the price doesn't mean much, so rather more than too little. The connections should of course be adequate and it's a good idea to give them a shot of protective spray (not WD40 IMO) after assembly & test. For lack of better, body rust protection (car!) can be used.

 

[fionn1432]

I'd have thought tinned cable would be all but essential for wiring to a bilge pump. It really should be used in all marine applications.
As for the amperage rating, the minimum is dictated by the current draw of the pump which we don't know. While undersizing cable isn't wise overspecifying that rating substantially has no benefit whatsoever but increases cable costs - though that probably aren't a consideration here.
For instance, Seaflo make a 1100gph pump which draws max 6 amps (probably momentary starting current) and suggest it is fused at 5a. A very pessimistic 6a at 12v as you know is 72watts. Your 20a cable is rated to draw 240w and that'll have a decent mnargin built in. Thus even this big pump draws only about a quarter of the capacity of your wire so unless your pump is unusually big or you plan to run four off the same cable it will be more than well able to cope.

It's a 1100gph blige pump

Purist? Arh... not been accused of that before. Like in ever.

The pump consumption (Amps - not water), the wire length and potential physical impact would be part of my considerations.

Unless the wires are really long, the price doesn't mean much, so rather more than too little. The connections should of course be adequate and it's a good idea to give them a shot of protective spray (not WD40 IMO) after assembly & test. For lack of better, rust body protection (car!) can be used.

Good idea

 

[ChromeDome]

1100 gph sounds plenty unless you break a seacock in which case it wont cope anyway.

Guessing: Rated consumption 4.1 A, required fuse 7.5 A

14 AWG is 2.5mm cross Sectional Area (CSA) will do fine over 4-5 metres. Personally have 4 mm on the shelf so use that for most unless space requirements dictate differently.

Do consider power supply to be constant, not switching off when you leave the boat.

 

[fionn1432]

1100 gph sounds plenty unless you break a seacock in which case it wont cope anyway.

Guessing: Rated consumption 4.1 A, required fuse 7.5 A

14 AWG is 2.5mm cross Sectional Area (CSA) will do fine over 4-5 metres. Personally have 4 mm on the shelf so use that for most unless space requirements dictate differently.

Do consider power supply to be constant, not switching off when you leave the boat.

And 14 AWG will be fine for both the pump and switch

 

[ChromeDome]

And 14 AWG will be fine for both the pump and switch

Yes. I presume the power to the pump goes through the switch so it will be under the same load.

Different if the switch controls a (low power) relay witch then sends the (higher) working power to the pump.

 

[fionn1432]

Yes. I presume the power to the pump goes through the switch so it will be under the same load.

Different if the switch controls a (low power) relay witch then sends the (higher) working power to the pump.

Yes thank you

 

[Refueler]

Contrary to all the experts ... I use cable usually intended for such as bedside lights etc. Tinned ? No. I have such wiring on my SR25 and its been in place for about 15yrs ... the only bit that has had to be replaced a few times - the choc block connectors.

Pump is an 1100GPH with auto float built in ... up to 6A @ 12V.

I have a suspicion that the cables fitted to the pumps may not be tinned anyway .. maybe ???

 

[fionn1432]

Contrary to all the experts ... I use cable usually intended for such as bedside lights etc. Tinned ? No. I have such wiring on my SR25 and its been in place for about 15yrs ... the only bit that has had to be replaced a few times - the choc block connectors.

Pump is an 1100GPH with auto float built in ... up to 6A @ 12V.

I have a suspicion that the cables fitted to the pumps may not be tinned anyway .. maybe ???

There tinned at the pump

 

[PaulRainbow]

Hi all
I'm planning to wire up a bilge pump and float switch they are both separate. They will be wired into a sea flo 3 way bilge pump switch. I have 14awg 12v 20amp cable. Would this cable be suitable for what I'm planning to do

Thanks View attachment 177782

Your 14awg cable is rated at 32a, the breaker on the switch panel is rated at 15a, so no need for an additional fuse between the switch and the pump.

If you intend (as would be typical) to wire this all directly to the battery, so it's always on, you should fit a fuse as close to the battery as possible, to protect the wiring between the battery and the switch panel. A 20a fuse here would be big enough to protect the wiring if it shorts before the switch and should ensure that is there is a short after the switch the breaker at the switch trips, rather than blowing the fuse.

 

[PaulRainbow]

Contrary to all the experts ... I use cable usually intended for such as bedside lights etc. Tinned ? No. I have such wiring on my SR25 and its been in place for about 15yrs ... the only bit that has had to be replaced a few times - the choc block connectors.

Pump is an 1100GPH with auto float built in ... up to 6A @ 12V.

I have a suspicion that the cables fitted to the pumps may not be tinned anyway .. maybe ???

Sorry, but this isn't "contrary to all the experts", it's contrary to all standards, good practice and common sense, it's just a bodge.

Domestic cable ? Untinned cable in bilges, chock block connectors in bilges (or anywhere else for that matter, especially non-stainless, with leaves) ?

Very poor.

 

[fionn1432]

Your 14awg cable is rated at 32a, the breaker on the switch panel is rated at 15a, so no need for an additional fuse between the switch and the pump.

If you intend (as would be typical) to wire this all directly to the battery, so it's always on, you should fit a fuse as lose to the battery as possible, to protect the wiring between the battery and the switch panel. A 20a fuse here would be big enough to protect the wiring if it shorts before the switch and should ensure that is there is a short after the switch the breaker at the switch trips, rather than blowing the fuse.

Thanks

 

[Refueler]

Sorry, but this isn't "contrary to all the experts", it's contrary to all standards, good practice and common sense, it's just a bodge.

Domestic cable ? Untinned cable in bilges, chock block connectors in bilges (or anywhere else for that matter, especially non-stainless, with leaves) ?

Very poor.

I don't disagree .. but 20yrs on - all still working fine. Of course there are 'better' ways to do it ..

The choc blocs are above water line and only 'air corrosion' ....

 

[lustyd]

Working fine isn’t necessarily the only measure of success. The outcome would be a potential fire risk as resistance increases, and this by its nature means it would work right up until the fire.
Not saying that’s the case, just highlighting that bad things can work and still be bad things.