Electric panel heaters..??

[sparkyjohn1]

I recently had another spark ring me up , about a job i completed late last year.Ranting that I havn't installed the heating circuit correctly, and i should re-visit to property to correct it.

The property didn't have a gas supply, so was asked to supply and Install a heating solution. ( electric rads / heaters etc.)

I have included a picture. ##best schematic diagram i could do on microsoft paint.##

This is how i did the job,, please tell me if you can find anything wrong with it..

Only thing i can think of is that the IN-LINE STAT, maybe borderline regarding max current draw,,,rated 16amp. but that is about it.. everything else seems o.k,??

Please let me know if you have any feedback..
thanks

 

[MDJ]

YEAH, its a 40 amp m.c.b,, but the max current draw is only 16 amp...!!!

I get your point, however is it 16 amp? 4.3 amps per kilowatt on 230 volts lol, anyhow I have mentioned the way to do the job with a contactor etc, I understand your view regarding an after thought by the customer.

 

[sparkyjohn1]

right ,,, last comment of the night,,, before i get too wound up about things,,
which one of you sparks out there would accept the circuit that i've installed as being safe ( tho not entirely orthadox.).. and which ones of you think that it is dangerous and needs to be altered??

 

[wozz]

But it is wrong, he has a potential 40 amp supply running through a 16 amp stat, what is right about that ??

How is 40A going to get pulled through the stat?

 

[MDJ]

not dangerous john

 

[tazz]

I get your point, however is it 16 amp? 4.3 amps per kilowatt on 230 volts lol, anyhow I have mentioned the way to do the job with a contactor etc, I understand your view regarding an after thought by the customer.

Which also raises MDJ question previously....why not install a 20a mcb...?

 

[sparkyjohn1]

And its actually 245 volts , (quite close to sub station,) not being picky or anything....

 

[sparkyjohn1]

thanks MDJ, really appreciate it...

 

[Badged01]

Not unsafe!. We can be finiky over what the total load is but its close enough for hard cash to 16A (diversity?) and whilst you could argue the 40A C/B is irrelevant as the characteristics of the loads mean its unlikely to carry overload current beyond the stat rating (assuming fault protection is covered) but maybe a 20A would give some piece of mind to someone if you wanted to make a change!

 

[tazz]

Not unsafe!. We can be finiky over what the total load is but its close enough for hard cash to 16A (diversity?) and whilst you could argue the 40A C/B is irrelevant as the characteristics of the loads mean its unlikely to carry overload current beyond the stat rating (assuming fault protection is covered) but maybe a 20A would give some piece of mind to someone if you wanted to make a change!

just the stat melting....before the 40a mcb trips.....but hey nevermind

 

[Badged01]

just the stat melting....before the 40a mcb trips.....but hey nevermind

But thats the whole point, its unlikely to see an overload current likely to melt it by the exact nature of the loads! (Fault current may be a different thing but Im assuming the RCD and installation method reduce the fault risk to a minimum).

Sections 433 and 434 expand on the rationale.

 

[tazz]

Old school....so practical designs, always safer.....rcd are not the be all and end all of safety....design as it were a bs88....and you still have the same disconnection time if not better, with an rcd

 

[Marvo]

The MCB in the CU isn't there to protect the devices on the circuit, it's there to protect the circuit itself. The way this is configured the actual supply circuit ends at the point it connects to the thermostat. Surely the supply circuit should end as a point of isolation such as a dp isolator or an FCU?

 

[tazz]

Exactly, you would want the maximum return fault current as possible, which would be distrupted by a failing device in the middle...ie the stat

 

[Marvo]

I like your thinking Tazz, I'd be interested to see if the t/stat has a kA rating equal or higher than the PSC current.

 

[tazz]

This is the thing abaut new regs.....they may have rcbo`s and rcd`s.....but if you go back to the 15th (which was a bit over the top on earthing...think Cockburn was on the committee) the system was the same, low impedance..high fault current, with quicker disconnection time...the standard was still minimum of 0.5 secs on a wired fuse