Water heater

[Ashley-Joseph]

When I turn water heater on lights flicker the mcb makes a buzzing noise the mcb is 40a but the heater is 11kw so it should be on a 50 also the service head fuse is 60a so this needs to be upgraded in my opinion.

 

[Vortigern]

So is this domestic or commercial? 11Kw is industrial type. Are you sure of the kilowatts.

 

[Ashley-Joseph]

Yeah

 

[pc1966]

The question to ask is not "Should the MCB be 50A?" but rather "Is the installed cable rated for 50A?"

What size of cable, and how is it routed? (i.e. the "method" that is used to determine the current rating of a given cable size based on its thermal insulation environment).

 

[Ashley-Joseph]

The question to ask is not "Should the MCB be 50A?" but rather "Is the installed cable rated for 50A?"

What size of cable, and how is it routed? (i.e. the "method" that is used to determine the current rating of a given cable size based on its thermal insulation environment).

Cable is a 6mm so I will have to upgrade that to a 10mm as well

 

[James]

It’s there any electrical heating in the property?

With 3/4 of the available supply being used for this water heater, it leaves very little left for everything else.

i Would expect a small dim of lights when this heater is drawing current, also I am not surprised about a bit of circuit breaker hum with 45A going through a 40A breaker..

I think you need to do some proper design work before throwing bigger cables and breakers in.

 

[Ashley-Joseph]

It’s there any electrical heating in the property?

With 3/4 of the available supply being used for this water heater, it leaves very little left for everything else.

i Would expect a small dim of lights when this heater is drawing current, also I am not surprised about a bit of circuit breaker hum with 45A going through a 40A breaker..

I think you need to do some proper design work before throwing bigger cables and breakers in.

I have done calculations for all the circuits like i said service head is on a 60 so i need to change this for a 100amp and upgrade the tails

 

[snowhead]

like i said service head is on a 60 so i need to change this for a 100amp and upgrade the tails

If this is in the U.K then you need to apply to the local DNO to have the service upgraded.
This may require them upgrading their service cable and also upgrading the local network.
There may be costs involved.

It cannot be assumed that there is spare capacity in the local network.

 

[DPG]

Surely he's not going to just change the DNO fuse himself is he ???

 

[Ashley-Joseph]

If this is in the U.K then you need to apply to the local DNO to have the service upgraded.
This may require them upgrading their service cable and also upgrading the local network.
There may be costs involved.

It cannot be assumed that there is spare capacity in the local network.

Sorry forgot to say the service head is 100a and 25mm tails there is a fused isolator that is on 60a that i need to upgrade along with the tails coming out of this.

 

[Marvo]

Yeah, the buzzing is'nt a fault as such, it's the sound of the MCB getting ready to do it's job by tripping due to overload.

 

[Pete999]

When I turn water heater on lights flicker the mcb makes a buzzing noise the mcb is 40a but the heater is 11kw so it should be on a 50 also the service head fuse is 60a so this needs to be upgraded in my opinion.

Lights flickering is down to Voltage Drop VD on a poorly designed installation.

Buzzing is down to the OCPD circuit breaker on/ ot near its tripping limit again to a poorly designed installation