garage

[still learning.]

sorry my original post was about a garage but i changed my mind and forgot to change the heading.

Hi, Ive been asked to look at a house where they have had an extention built, in the extention when something is plugged into a socket and turned on the lights dimm, before I go and look can any one tel me what might be the cause of this.
Also in another house a lamp plugged into a socket dimms when the power shower is turned on?

cheers
craig

 

[pushrod]

might be voltage drop in cables caused by the increased current demand.

 

[Johno]

I agree with pushrod, in my house when I turn on my electric shower my lights dim a bit, can only be volt drop (I think)!

 

[still learning.]

thanks, is there anything I can do to stop it.

craig

 

[pushrod]

somewhere along the line i would guess that there would be cables that are too small for the demand. Reducing demand on a circuit (possibly by splitting the circuit), shortening runs and increasing cable size all reduce volt drop.

You could check the voltage to see what is actually happening.

 

[pushrod]

just read your original post again and and as it is a new extension an obvious thing to check is to see if someone hasn't put the lighting on the same circuit as the power, possibly via an FCU. Allowed volt drop for lighting is only 3%. Another possible culprit could be a sub- main exported on too small a cable - if it is, remember that volt drop is calculated using the run from the original supply not the sub-main.

With the power shower case they should obviously be on different circuits, but it might be worth looking at the length and size of the tails if it is an old installation, particularly if the shower is really taking a big current.

If it is a modern split CU you might be able to solve the problem by moving one of the circuits onto the other side, but remember both the shower and the sockets should both be rcd protected. Be interested to hear what it is - in a few months i might be in the same situation myself !

 

[still learning.]

thanks pushrod,

not sure about the extension till i look at it but i do know the shower was put it over 7 years ago And the current owners inherited the problem, so i would imagine the shower was wired into the ring as i was told it doesn't have it's own fuse but don't know for sure so probably spured and would just want putting on it's own circuit.

 

[m25maintenance]

check also that the circuit breakers are in correct order, highest rated nearest the main switch, but i agree with other lads, the lights might be spured from the power circuit