Is it acceptable to bypass battery isolator switch?

rwoofer

rwoofer

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Following on from my earlier autpilot question, I have now had it installed. Apart from the fact the installer did not finish the job, the most worrying thing for me is that he bypassed the battery isolator, so that the autopilot is always live. Is this acceptable?

I always thought everything has to be through the isolator, in case of a problem, risk of fire etc. Just trying to get a feel for how much I need to throw the book at them for a shoddy and possibly dangerous job.
 
Wise to isolate IMHO, but on re-wiring this winter I had the "man with the tools" hard-wire the radio/audio/CD player - solely so that channel station info wouldn't be lost when all power turned-off.
I am also getting the auto-bilge pump hard-wired so that it will work independently and be available in case of significant water-ingress. (I'll be checking the bilges at least weekly)
 
Its a compromise. Everything through the isolator makes sense. You don't bypass your house fuse box - EVER. BUT you also dont turn your house electrics off when you go out...

If its in-line fused and switched its relatively safe - only issue being that you cant switch it all off with a single master switch.

does it have memory that requires power? So like in the olden days my parents were appauled that they had to leave the VCR pluged in (they unplugged the telly at night!) so it remembered the time? If so is there actually two power feeds one direct to battery - very low current and a second the other side of the isolator? Bit like a car radio?
 
It's definitely not the way I wire my boats. With two exceptions, automatic bilge pump and permanent wire to the FM radio, off means off. Some people have the VHF permanently live although I can never see the logic in that. Definitely not the autopilot IMHO. You would never want it on its own anyway. The only possible reason might be high current draw necessitating direct connection to the battery but there are plenty of alternatives to that.
 
Quite common to have it as an "always on", particularly on a small boat when you might want to sail without the electrics on. The AP is protected by its own fuse in line. some circuit deigns have an always on distribution box for things like APs, auttomatic bilge pumps, radios etc.
 
I would think the autopilot should go through an isolation switch, mine does anyway. I have a lot of items that by-pass it though. Each individually fused. Webasto heater, radio/CD changer, gas alarm, bilge pump, ... enough to worry me, so I set up an extra isolation switch for them all, only used in case of fire.
 
ShinyShoe said:
Its a compromise. Everything through the isolator makes sense. You don't bypass your house fuse box - EVER. BUT you also dont turn your house electrics off when you go out...

If its in-line fused and switched its relatively safe - only issue being that you cant switch it all off with a single master switch.

does it have memory that requires power? So like in the olden days my parents were appauled that they had to leave the VCR pluged in (they unplugged the telly at night!) so it remembered the time? If so is there actually two power feeds one direct to battery - very low current and a second the other side of the isolator? Bit like a car radio?
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Fused and wired to pole on isolator (not battery) - only one feed to radio.
Good point that it/they can't be turned-off by main isolator switch, but easy to whip-out the fuse(s)
 
I can't see any reason, other than laziness/botching to wire an ST2000 (?) direct. If I want to use the tiller pilot then I will also want to use instruments and radio.
 
vyv_cox said:
It's definitely not the way I wire my boats. With two exceptions, automatic bilge pump and permanent wire to the FM radio, off means off.
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Rigger Mortice said:
I can't see any reason, other than laziness/botching to wire an ST2000 (?) direct. If I want to use the tiller pilot then I will also want to use instruments and radio.
Click to expand...

+ 1 on both, though I also have the (fused) feeds from the solar panel controller connected to the battery terminals of the 1-2-both switch
 
>. Apart from the fact the installer did not finish the job, the most worrying thing for me is that he bypassed the battery isolator, so that the autopilot is always live. Is this acceptable?

No it just eats battery power, the only thing that should be wired direct to the battery is the gas alarm.

>BUT you also dont turn your house electrics off when you go out...

We turn every plug off so no need to turn the main fuse switch off.
 
rb_stretch said:
Following on from my earlier autpilot question, I have now had it installed. Apart from the fact the installer did not finish the job, the most worrying thing for me is that he bypassed the battery isolator, so that the autopilot is always live. Is this acceptable?

I always thought everything has to be through the isolator, in case of a problem, risk of fire etc. Just trying to get a feel for how much I need to throw the book at them for a shoddy and possibly dangerous job.
Click to expand...

It is an item which draws a fairly high current when operating and which will not take kindly to volts drop in its supply.

A direct feed from the switched side of the isolator, via its own fuse, could therefore be a good idea but not direct from the battery unless provided with its own isolator.

I hope your installer did fit a fuse close to its connection to the supply. By passing the isolator may be unacceptable but installing it without a fuse would be dangerous.
 
KellysEye said:
the only thing that should be wired direct to the battery is the gas alarm.
Click to expand...

I'm curious, why? I can't see the benefit of a gas alarm going off when there is nobody on the boat. Surely, all it will do is flatten the battery if it goes off?

I can understand radio memories, bilge pumps and solar/wind charging bypassing the isolator switches.
 
I am surprised a "pro" would do it in such a way as it doesn't conform to industry standards, either BMF, BSI or NMEA0400. Everything should go through the isolator with the following exceptions.

Outboard engine circuits with with circuits only for starting, navigation and lighting.

Electronic devices with protective memory, bilge pumps and alarms.

Safety ventilation fans for fuel & battery compartments.

Manufacturers instructions of CE marked kit where specified.

Charging devices intended for use when the vessel is unattended. All exceptions call for a protective over current device as close as practical to the battery terminal.
 
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davidpbo said:
I don't know whether it is correct or not, but IMHO a battery isolator switch should be that and totally isolate the battery.

If differentation is required, that should be another switch further up the line to switch off items not normally required to be connected to the battery when the boat is not in use.
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I have a separate isolator for the domestic battery, but the 0-1-2-both switch is the only isolator for the starter battery. The only thing that bypasses it is the feed from the solar controller. If I need to isolate that, I can pull the fuse out The domestic battery goes through an isolator switch to the No 2 position on the 0-1-2-both and thence to the switch panel. Bilge pumps and stereo memory are upstream of the master switch, though the pumps have their own switches that I leave on auto. Everything else is downstream of the master. When leaving the boat, the 0-1-2-both goes to 0 and the master is turned off, allowing solar charging of both batteries, the radio to keep its memory and the bilge pumps to work on automatic.

The domestic isolator only gets turned off if I want to work on the switch panel. If it failed, I probably wouldn't bother to replace it as I could just disconnect the battery.
 
I can see no good reason to connect a tillerpilot direct to the battery.

The only things I have connected upstream of the isolator are the 240v charger and the Smartgauge battery monitor. If I had solar/wind these would obviously count too.

If your man has wired it this way, I suggest you check ASAP whether there's a fuse within a few inches of the battery to protect the new cable. If not, it's a fire hazard that needs correcting immediately.

Why would you pay someone to screw up your boat in this way?

Pete
 
KellysEye said:
>BUT you also dont turn your house electrics off when you go out...

We turn every plug off so no need to turn the main fuse switch off.
Click to expand...
You unplug your fridge?
Even unplugging doesn't mean there won't be a fault on the ring main? And you can't non ring appliances..

Rigger Mortice said:
I'm curious, why? I can't see the benefit of a gas alarm going off when there is nobody on the boat. Surely, all it will do is flatten the battery if it goes off?
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Some people will isolate when sleeping aboard at night if they need no kit on... It means you are sure nothing is draining the battery. Or if you know you have a fault on electrics you switch off while you investigate.. You'd want v to know if you accidentally had a has leak too... Plus the first thing most people do when they get aboard is turn everything on.. Gas... Electric... Bang. Of you get aboard to a beep you may think twice about electric on... Also think my has alarm takes three minutes to balance out... I could have lot the has under the kettle by then. Boom.
My gas alarm has its own in line fuse. Of I'm around and power fails it bleeps 5 times. Of I'm not around then I can see its little green LED as I enter the cabin space before I get to battery... It's my first glance do I have any power test..

davidpbo said:
As an aside, because my electrics do need looking, can you get battery terminals with a couple of fuse holders and connections on top?

Yes you can, sorry should have searched first.
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Ah but someone like me will still come along and write something direct to the terminal which they don't want killed if something fuses the rest of supply.
 
ShinyShoe said:
Ah but someone like me will still come along and write something direct to the terminal which they don't want killed if something fuses the rest of supply.
Click to expand...

I assume the idea of the battery terminal with a couple of fuses on top (not seen one myself) is that your special things each have their own fuse for their cable. So they're immune from something else blowing some other fuse, but your boat won't be set on fire by a short in the cable to your special device.

Pete
 
The whole concept of a battery isolator is interesting. In fact a big question. Why?
Now years back on a boat it was OK to completely isolate the battery as there were not invented devices which could or should be left running 24/7. So it seemed like a good idea to isolate everything when you leave the boat. At least leaving owner with a good feeling about safety. Likewise the safety standards for commercial boats picked up this idea that great safety can be achieved by isolation. Or quick and easy isolation can be achieved by a simple operation of an isolation switch in the case of smoke smell or a fault.

However today we have so many devices that need to be powered 24/7that any isolation switch will only provide partial isolation anyway.

Then again look at your car. Power to the starter is not isolated relying only on the starter solenoid for isolation. The ignition switch does isolate many services but just as many seem to operate without ignition or acc turned on.

Light aircraft usually have a remotely switched master switch relay. So more like a boat than a car but still so many circuits bypass the master relay anyway due to need for 24/7 powering.

Back to the OP yes certainly the autopilot should have been connected down stream of the isolator and by another fuse in the main fuse board. Thus the autopilot wouldn have been isol;ated as you would expect by the isolator switch. But the real danger outcome is a bit less clear. good luck olewill
 
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