48 V DC max bus bar, for 48 V (60 V) AGM battery?

[Blisterlover]

If I have a bus bar that's rated for 48 volt DC maximum voltage, can I use it on a battery system that is four 12 volt AGM batteries wired in series to get 48 volt, equaling 60 volts when fully charged?

[BillKny]

Which part of 48 volts Maximum did you not understand?

[smac999]

I can't see how a buss bar would care at all.

switches etc are different as they will arc when opened / closed.

[Bycrick]

As a guess only, I can think of two possibilities:
1. The least probable is that the mounting base insulation might not be sufficient if mounted on a conductive bulkhead.
2. More likely, somewhere around 50 volts, one goes from "low-voltage" standards to "high-voltage" standards. I’d bet that it doesn’t meet the coverage and protection standards for a higher voltage circuit.

I doubt that using it would be an electrical disaster, or a major safety problem. But in general, a 60-volt system isn’t necessarily the same as a 12 volt system. Proper design and spec from the start is a good idea.

[Statistical]

It will be fine. The busbar doesn't care. It is a bar of conductive metal. Amperage not voltage drives resistance requirements. If it was high voltage (>1500 VDC) the breakdown voltage of any insulating standoffs might matter but not at 48v especially not if affixed to a plastic boat.

Fuses and switches that is where you have to be careful although even there they likely say 48v nominal meaning designed to go higher than that.

[Statistical]

Originally Posted by Bycrick

As a guess only, I can think of two possibilities:
1. The least probable is that the mounting base insulation might not be sufficient if mounted on a conductive bulkhead.
2. More likely, somewhere around 50 volts, one goes from "low-voltage" standards to "high-voltage" standards. I’d bet that it doesn’t meet the coverage and protection standards for a higher voltage circuit.

I doubt that using it would be an electrical disaster, or a major safety problem. But in general, a 60-volt system isn’t necessarily the same as a 12 volt system. Proper design and spec from the start is a good idea.

And even there the 50V 'cutoff' isn't really that cut and dry. There is a suprising lack of standardization.

The IEC defines ultra low voltage as <60 VAC or <120 VDC. With low voltage (aka supply voltage) above that. Yes most non-electrical engineers often call 120VAC or 230 VAC "high voltage" but it is low voltage with ultra low voltage what most people call low voltage. Side note this is why if you see a genuine "high voltage" warning sign you should take it seriously. If properly labeled it means >1000 VAC or >1500 VDC.

In the US well three are three relevant standard and none of them are consistent with each other. The NEC defines ULV as <50 V (both AC and DC). The NFPA has an "extra low voltage" standard which is 30VAC or 60VDC but limited to dry locations with wet locations being 6VAC and 30VDC. The UL has a low-voltage limited energy standard which is limited to 42.4V.

So yeah ... ultra low voltage depends on who you ask. AC is significantly higher risk than DC for the same voltage. Although not all standards take that into account.

ut in general, a 60-volt system isn’t necessarily the same as a 12 volt system.

Well 12V is 12V nominal. It can reach peak charging voltages of 16.8V at cold temps if you have a temperature adjusted charger. Apples to apples it is 12V nominal and 48V nominal.

[Manateeman]

Blue Sea Systems measures amp capacity from one end to the other. BEP, which is a sister company, measures it from the center to the ends.
The Blue Sea bar is twice the weight. If you google copper buss bars, there is information on what size bar will carry your load.
It ought to be large enough so it’s cool running.
Just curious, but what sort of application or boat equipment are you designing.
Happy trails to you.
Mark and his manatee crew who designed a Van de Graaff powered pizza oven.

[Tellie]

Post a pic of this buss bar and what application you intend to use it for.

[GordMay]

Originally Posted by Statistical

... In the US well three are three relevant standard and none of them are consistent with each other. The NEC defines ULV as <50 V (both AC and DC). The NFPA has an "extra low voltage" standard which is 30VAC or 60VDC but limited to dry locations with wet locations being 6VAC and 30VDC...

I don’t understand. The NFPA 70 IS the National Electrical Code (NEC).
Bycrick raised some applicable issues (Post #4).

The relationship between NEC, UL, NRTL, NFPA 79, “Listed” and AHJ in industrial electrical installations
➥ https://www.righthandindustrial.com/...installations/

[Statistical]

Originally Posted by GordMay

I don’t understand. The NFPA 70 IS the National Electrical Code (NEC).
Bycrick raised some applicable issues (Post #4).

The relationship between NEC, UL, NRTL, NFPA 79, “Listed” and AHJ in industrial electrical installations
➥ https://www.righthandindustrial.com/...installations/

Sorry for being imprecise. NFPA 79 6.4.1.1 also defines a PELV standard which is different than ULV defined in NFPA 70 (NEC).

6.4.1.1
PELV circuits shall satisfy all of the following conditions:
(1) The nominal voltage shall not exceed the following:
(a) 30 volts ac (rms value) or 60 volts dc (ripple-free) when the
equipment is used in normally dry locations and when large area
contact of live parts with the human body is not expected
(b) 6 volts ac (rms value) or 15 volts dc ( ripple-free) in all other cases

My larger point was just that
a) there is no universal international 50v cutoff.

b) although less than ideal electrical manufacturers often list parts based on nominal voltage. 24V and 32v systems do go above 24v and 32v and yet blue marine has plenty of components marked as 24v and 32. It doesn't mean that you have to disconnect them when the system is charging (voltage > 24v or 32v) just that they are being loose and using the nominal voltage.

To the OP I would revise my prior statement to clarify voltge isn't the issue. As others have pointed out make sure the bus bar is rated for the ampacity you will be pulling and the system is fused so that the rated amps of the busbar can't be exceeded.