No power to spur

[lex101]

Hi all

Had a bit of a bad day.

Went to diagnose a "no hot water" issue in a Tk maxx cleaner cupboard and found there was no supply to the fused spur.
Went to the plant room and no mcb down or one labelled for the water heater. Bms panel contactor not pulling in. Not even sure it's the right one. Checked for hidden boards and nothing but AC panels. Checked the cable and it has been thrown across the ceiling void and onto basket going towards the plant room. Nothing labelled. No diagrams for bms panel. Checked for power on the out going circuits incase one was down. Nothing wrong. Any ideas? Thinking of getting a fuse finder tomorrow and try again on Monday. Are they any good? ..doing my head in now.

 

[Pete999]

Where does the supply to your "spur" originate I only ask as it could be from a socket outlet and the cores or one core may be disconnected.

 

[lex101]

This is the problem. I can't find an origin of supply. I was hoping that due to there being a water heater switch on the bms panel, that the circuit would pass through it from an mcb in the cu rather than be spurred off of a socket somewhere.

 

[Farmelectrics]

Might be quicker to run a new supply in

 

[Pete999]

Might be quicker to run a new supply in

What and leave a duff cable hanging around somewhere? that's a bit naughty.

 

[snowhead]

If there is a BMS controlled contactor not pulled in.
And there's also a Water heater switch the BMS controls,
Have you tested the cable between the heater and contactor to see if they are 1 and the same,
And also checked the incomer to the contactor to see if it's Live, maybe fed from an unmarked MCB????

 

[lex101]

The problem with the contactors is that they are not labelled or mentioned on the drawings. There are no unaccounted for mcbs as they supply tills sockets and a seperate board covers lighting. The incoming supplies to the unlabelled contactors are live but no voltage present at the panel switch. I would carry out a continuity test if there was an mcb to test from. Like pete999 said, the heater could worryingly be wired from a spur and the switch on the bms hasn't been working for years!

 

[Farmelectrics]

No Pete make safe first terminate into a jib and the run new supply in just a thought

 

[snowhead]

The problem with the contactors is that they are not labelled or mentioned on the drawings. There are no unaccounted for mcbs as they supply tills sockets and a seperate board covers lighting. The incoming supplies to the unlabelled contactors are live but no voltage present at the panel switch. I would carry out a continuity test if there was an mcb to test from. Like pete999 said, the heater could worryingly be wired from a spur and the switch on the bms hasn't been working for years!

It doesn't stop you testing Outgoing on the Contactor that's not pulled in, to the Water heater spur.

What voltage are the contactor coils?

The Water heater switch on the panel, is it Hand / Auto / Off or just On / Off?

The heater circuit won't pass through the switch,.
The switch will just be in a control circuit for the contactor.

They'll more than likely be a link the Fire alarm circuit to disable the heater circuit.

.

 

[lex101]

True and I'll check it next week. Still won't tell me where the supply is though as none of the mess of cables is labelled. The coil voltage on the contactor is 24v ac. The swich is either off/ auto.

I would be tempted to run a simple new radial circuit but with one possibly already there and possibly going through the trend, I'd rather not have that headache as well.

 

[Pete999]

No Pete make safe first terminate into a jib and the run new supply in just a thought

Thought that statement was a bit iffy for you, lol

 

[Lagentium]

Why would a water heater have to run via the BMS? Is it being taken for granted that it does, or it did? If the contactor is isolating the Live and Neutral I'd be tempted to do a continuity check on them, to confirm if they are the correct wires. The switch on the panel maybe from a PLC, so check you are testing on the correct settings, or see if the input is showing if possible. Do you have a picture?

 

[snowhead]

Why would a water heater have to run via the BMS?

Timed to be on only during occupancy, energy saving.

 

[Flanders]

Just check there are not other water heaters on site and if there are you can oliminate them at the bms when tracing out it could be that this water heater was added at a latter date and not connected to the bms just a radum switch ot time clock , good luck im sure it will be somthing simple when you find it is always is

 

[YoungBart]

As has been mentioned before check it hasn't been Spurred off any sockets above or behind it, the experience I've had in commercial property's tells me cleaners cupboards tend to be a last minute addition or bodge, the BMS panel could well be controlling any WH's in the public WC's id have guessed.