Do the lighting requirements change for the machine shop described in Example 9.4 if the luminaries are still to be hung at 13^' but suspended from a 41^' ceiling?

Question

Do the lighting requirements change for the machine shop described in Example 9.4 if the luminaries are still to be hung at [latex]13^{'} [/latex] but suspended from a [latex]41^{'} [/latex] ceiling?

Accepted Answer

Steps 1 and 2. The same as Example 9.4.
Step 3. According to Equation 9.9, the CCR may be calculated as

[latex]CCR=\frac{(41-13)}{(13-3)} imes 1.75=4.9[/latex]

Step 4. As in Example 9.4, the WR and BCR are 80%. According to Table 9.7, the ECR is 58%.
Step 5. Given that fluorescent lamps in uncovered fixtures are still to be utilized, the CU may be interpolated from Table 9.8 as .75.
Step 6. Unchanged from Example 9.4.
Step 7. According to Equation 9.10, the number of lamps required if 60 watt fluorescent lamps are utilized is

Number of lamps[latex]=\frac{(100)(100)(40)}{(0.75)(0.85)(3300)} =191[/latex]

If two lamps are placed in each luminary according to Equation 9.11, then 96 luminaries are required.
Step 8. Table 9.8 indicates that for a mounting height [latex]10^{'} [/latex]above the work surface, the luminaries should be spaced apart no more than [latex]13^{'} [/latex]. Each fluorescent fixture is [latex]4^{'} [/latex] long. By placing four rows of [latex]24^{'} [/latex] luminaries along the long axis of the machine shop so that each row begins and ends [latex]2^{'} [/latex] from the wall and the first and last rows are [latex]5^{'} [/latex] from the wall and all other rows are spaced [latex]10^{'} [/latex] apart, the illumination
level within the room will be evenly distributed and adequate to perform
the required tasks. This lighting layout is shown in Figure 9.11.
The lighting information given to the person planning the electrical services should include a lighting layout and a description of the type of luminaries and lamps to be used. With this information and the location of the equipment required for electrical services, as described on the department service and area requirement sheets, the total electrical service requirement can be planned.

Table 9.7 The Percent (%) Effective Ceiling Reflectance (ECR) for Various Combinations of Ceiling Cavity Ratios (CCR),Wall Reflectances (WR), and
Base Ceiling Reflectances (BCR)

	BCR
	80						65						50						37						10						5
	WR						WR						WR						WR						WR						WR
CCR	80	65	50	35	10	5	80	65	50	35	10	5	80	65	50	35	10	5	80	65	50	35	10	5	80	65	50	35	10	5	80	65	50	35	10	5
0.5	76	74	72	69	67	65	64	60	58	56	54	52	49	47	46	44	42	41	36	34	32	31	29	28	12	12	11	11	9	8	8	8	7	6	5	5
1	74	74	71	67	57	56	60	55	53	49	45	43	48	45	43	39	36	35	35	33	31	20	26	25	14	13	12	11	9	8	10	7	8	7	5	4
1.5	72	67	62	55	49	47	58	52	49	44	38	36	47	44	40	35	21	28	35	33	20	26	21	20	16	15	12	11	8	7	14	11	9	7	4	4
2	69	72	67	62	41	39	55	49	44	38	32	30	46	42	37	31	26	25	35	32	28	23	18	17	18	17	13	10	8	6	15	12	10	7	4	4
2.5	67	60	51	43	35	33	54	45	40	33	26	25	46	40	35	28	22	21	35	31	26	21	16	13	20	19	13	10	7	5	17	14	10	8	3	3
3	65	57	47	38	30	28	53	42	38	29	22	21	45	39	32	25	19	18	35	31	24	20	14	12	21	20	13	10	7	4	19	15	11	8	3	3
3.5	63	54	43	34	26	25	52	39	33	26	18	17	44	38	30	23	17	16	35	31	23	18	12	10	22	21	13	10	7	4	20	16	11	8	3	3
4	61	52	46	31	22	21	50	37	31	23	15	14	44	38	28	21	15	13	34	30	23	17	10	8	23	22	14	10	7	3	20	17	12	8	3	2
5	58	46	35	26	18	15	48	33	26	18	9	8	42	35	25	18	12	10	34	29	21	16	9	7	25	23	14	10	6	3	23	18	12	8	3	2
8	50	36	25	17	11	6	41	24	18	11	5	3	40	30	19	13	7	5	34	28	17	11	5	4	27	24	13	10	5	2	26	19	12	6	3	1

Table 9.8 Coefficients of Utilization for Standard Luminaries

Luminaire	Spacing Not to Exceed	RCR	ECR
			80%				50%				10%				0%
			WR				WR				WR				WR
			80%	50%	30%	10%	80%	50%	30%	10%	80%	50%	30%	10%	0%
Filament reflector lamps	1.5× mounting height	1	1.11	1.09	1.07	1.03	1.04	1.02	1.00	.98	.96	.95	.94	.93	.91
		2	1.04	1.00	.95	.92	.99	.95	.92	.88	.92	.90	.87	.85	.83
		3	.95	.92	.88	.82	.92	.88	.84	.80	.85	.83	.80	.77	.75
		4	.9	.85	.76	.73	.86	.81	.76	.71	.79	.77	.73	.70	.68
		5	.82	.77	.71	.65	.80	.75	.69	.64	.75	.71	.67	.63	.61
		10	.58	.50	.43	.38	.54	.49	.43	.38	.51	.47	.42	.38	.36
High-intensity discharge lamps (mercury, metal halide, or sodium)	1.3× mounting height	1	.89	.87	.84	.82	.81	.80	.78	.77	.74	.73	.72	.71	.70
		2	.82	.79	.75	.72	.77	.74	.71	.68	.70	.68	.66	.64	.63
		3	.76	.72	.67	.63	.72	.68	.64	.61	.65	.63	.60	.58	.56
		4	.7	.66	.61	.57	.67	.63	.58	.55	.57	.55	.54	.53	.51
		5	0.64	.60	.55	.51	.62	.58	.53	.49	.56	.54	.52	.49	.46
		10	.45	.40	.34	.30	.42	.38	.34	.30	.40	.36	.41	.20	.28
Fluorescent lamps in uncovered fixtures	1.3× mounting height	1	.88	.85	.82	.79	.79	.65	.72	.71	.65	.64	.63	.62	.59
		2	.78	.75	.70	.65	.71	.67	.63	.59	.60	.57	.55	.52	.50
		3	.69	.66	.60	.55	.63	.59	.54	.50	.54	.51	.48	.45	.42
		4	.61	.59	.52	.46	.56	.52	.47	.43	.48	.45	.41	.38	.36
		5	.53	.51	.44	.39	.51	.46	.40	.39	.43	.40	.36	.33	.30
		10	.35	.30	.23	.19	.32	.27	.21	.18	.26	.23	.19	.16	.14
Flourescent lamps in prismatic lens fixtures	1.2× mounting height	1	.56	.63	.61	.59	.60	.59	.58	.56	.56	.55	.54	.53	.52
		2	.6	.57	.54	.51	.56	.54	.51	.49	.51	.50	.49	.47	.46
		3	.54	.51	.48	.44	.51	.49	.46	.43	.47	.46	.44	.42	.41
		4	.49	.46	.42	.39	.48	.44	.41	.38	.44	.42	.39	.37	.36
		5	.45	.42	.37	.34	.44	.40	.36	.34	.40	.38	.35	.33	.32
		10	.31	.26	.21	.18	.29	.25	.21	.18	.27	.24	.20	.18	.17

Question 9.5: Do the lighting requirements change for the machine shop des...

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