Is this dist board overloaded?

[jibspark]

Hi all,

ive got a feeling that this db is overloaded but i cant remember the best way to calculate it.

Hair Salon

100A Main fuse

10a lighting

10a lighting

10a lighting

25a water heater

25a water heater

32a 4mm radial - sockets

32a 4mm radial - sockets

32a 4mm radial -sockets

50a radial -sunbed

it all seems a bit steep to me.

 

[Riggy]

If each of the circuits is correct in terms of cable size, etc., there is no sign of thermal damage and the 100A fuse never blows, then obviously there's enough diversity in there!

 

[The Godfather]

If each of the circuits is correct in terms of cable size, etc., there is no sign of thermal damage and the 100A fuse never blows, then obviously there's enough diversity in there!

The Don would agree, overloading of any consumer unit, will normally leave signs as such.

Don & His Boys

 

[Apache]

Jib - have you gone around and worked out what a realistic load is?

eg 3 10A lighting circuits may only be drawing a couple of amps each........

Daft question but it's not spread over 3 phases is it.............?

 

[jibspark]

nope not spread over three phases, the lighting will be bugger all. to be honest i was talking from a regs point of view rather than a practical point of view.

it just made me think when i saw a 50A mcb in an almost domestic situation, (well light commercial).

 

[the doctor]

hi

sometimes, if not sure, i have left a clamp meter around the tails and asked the customer to switch it on and check it every hour or so to record the general loading during the day

now and again these loadings can look worse than they actually are.....

 

[SPECIAL LOCATION]

nope not spread over three phases, the lighting will be bugger all. to be honest i was talking from a regs point of view rather than a practical point of view.it just made me think when i saw a 50A mcb in an almost domestic situation, (well light commercial).

???

There is no regs point of view... ?:| Just a practical point of view. :|

re-read OSG page 95 second paragraph...

APPENDIX 1: MAXIMUM DEMAND & DIVERSITY

The information and values given in this appendix are intended only for guidance because it is impossible to specify the appropriate allowances for diversity for every type of installation and such allowances call for specialist knowledge and experience. the values given in table 1B, therefore may be increased or decreased as decided by the installation designer concerned.....

you need to work out realistic loads for connected appliances/accessories

then which of those loads a simultaneously on for a specific duration.

 

[Apache]

you need to work out realistic loads for connected appliances/accessories then which of those loads a simultaneously on for a specific duration.

bit like what I said

evening SL

 

[SPECIAL LOCATION]

bit like what I said evening SL

Quite so sir Patch.....

Applaud SmileyApplaud Smiley

But i did back mine up with a quote from the little red bedtime story book!Blushing:z

:coat

 

[green-hornet]

Even a quick basic calculation for diversity would put it to around 94 amps.

Realisticly I would think nothing like that would be drawn at any one time.

The quick method I use is add all the used breakers together then multyply by 0,412.

Should only be used as a rough guide and drfinately not for designing an installation.

 

[jibspark]

Even a quick basic calculation for diversity would put it to around 94 amps.Realisticly I would think nothing like that would be drawn at any one time.

The quick method I use is add all the used breakers together then multyply by 0,412.

Should only be used as a rough guide and drfinately not for designing an installation.

Cheers GH!

Out of intrest, why .412?

 

[Apache]

Cheers GH!Out of intrest, why .412?

It has been pointed out elsewhere that as installations are broken down into smaller parts to minimise nuisance tripping this may be less valid

ie olden days 1 lighting circuit, 1 ring up 1 ring down, now upstairs and downstairs lighting separate, separate ring for kitchen etc adds a couple of extra breakers but no extra load

 

[Andy™]

It has been pointed out elsewhere that as installations are broken down into smaller parts to minimise nuisance tripping this may be less validie olden days 1 lighting circuit, 1 ring up 1 ring down, now upstairs and downstairs lighting separate, separate ring for kitchen etc adds a couple of extra breakers but no extra load

but commercial is a little different to domestic, so that figure may not work out here.

how much power does the sunbed actually use? it may be a 50A because of starting current, but use much less . how often are the heaters used (and at the same time?). is there much plugged into the rings?

at a guess, id say your OK with it. unless the insulation is melting away from the copper, then there may be a problem

 

[jibspark]

i should get called back to replace an isolator so i will put a clamp meter on the sunbed, the heaters are for washing hair so i would think they are on all time. as for the sockets, its pretty much just hairdryers. lol no insulation melting although when i opened up the isolator for the sunbed i was faced with some connector blocks where they had just bypassed the isolator and just used it as a jb!! oh and the L1 terminal of the isolator had melted slightly!

out of interest, if you found this what code would you give it?

 

[Andy™]

depends how badly its burnt. if its bad, code 1, otherwise 2

 

[jibspark]

the thing that got me the most was the fact the isolator wasnt being used as an isolator. anything that gets switched to the off position and remains live is just asking for trouble!

i gave it a 1.

 

[Andy™]

defiantly 1!