Bosch Pump Current Draw

[Richard71]

I have a Bosch pump as supplied by Prestige. It's wired through a relay & inertia switch. My issue right now is I've just fitted the boot space interior trim and find the cable supplying the pump a few inches too short to be hidden away behind the adjacent trim panel.

I'll pay a visit to CEF or somewhere similar tomorrow for a meter of white and a meter of black cable, I'm just not certain what size to be asking for.

Any advice appreciated.

Richard.

[Waldi]

Hi Richard,

I also had to lengthen my harness and used 2.5 mm2. I also made the earth of this same thickness. 2.0 mm2 would probably do but there is no noticable difference in cost or thickness.

Equally inportant is to have proper connectors, I used the un-insulated crimp connectors, not the blue-red-yellow ones.

And a good clean bare metal earth point for the black earth wire. Mine was earthed through the loom, but I made an additional earthing point on the body, so have a “parallel” earth.

Waldi

 

[Richard71]

Thanks Waldi,

I've ordered some cable from Autosparks that's good for 17.5 amps, that should suffice.

Richard.

[Waldi]

Richard,

Autosparks are a good source, they supplied my harness too, all good.

But to be sure, I would ask for 2.5 mm2, not just “17.5 A”.

The definitions on the rating differ: max, avg, at what voltage drop/length etc.

Regards

Waldi

 

[barkerwilliams]

As above I would over-rate a fuel pump cable. Electrical cables are rated by the amount of heat they can dissipate, you will note that "thin wall" cable is rated higher than PVC for the same conductor size. As the pump runs continuously, perhaps for hours on end the heat build-up will be considerable. As the cable heats the resistance increases and the voltage drop increases, and the pump draws more current to maintain pressure so more heat is generated.

As per Waldi above, for the few pence extra I would buy large.

And what goes down the wire has to come back on a Bl**dy good earth, not just a good earth.

Alan

[Steves_TR6]

49 minutes ago, barkerwilliams said:

As above I would over-rate a fuel pump cable. Electrical cables are rated by the amount of heat they can dissipate, you will note that "thin wall" cable is rated higher than PVC for the same conductor size. As the pump runs continuously, perhaps for hours on end the heat build-up will be considerable. As the cable heats the resistance increases and the voltage drop increases, and the pump draws more current to maintain pressure so more heat is generated.

As per Waldi above, for the few pence extra I would buy large.

And what goes down the wire has to come back on a Bl**dy good earth, not just a good earth.

Alan

100% agree!

[Richard71]

I called Autosparks earlier to amend my order, I explained what the cable will be used for and was advised by one of their techs that the cable originally ordered will be absolutely fine, 2mm2...… . When it arrives I'll compare it to what I've removed.

Richard.

[Waldi]

Hi Richard,

I think 2 sqmm should be fine, according to a Dutch wire supplier, similar to Autosparks.

From that site:

1.5 sqmm: 13,5A (that would be just enough)

2,0 sqmm: 17.5 A (enough)

2.5 sqmm: 21.75 A (certainly enough, also in a warm boot.

Note: there are several standards, with different ratings, this is the most conservative on that site.

Autosparks could well be referring to the same information.

But there is also an EU spec on that site that allows 16.5A for a 1.0 sqmm wire, hence my preference to specify cross-sectional area (sqmm) instead of rated current (A).

Here is a link, some is in English:

https://www.rdae.nl/draad-en-kabel/enkeladerig-draad/draad-info-pagina/

Cheers,

Waldi

Edited June 19, 2019 by Waldi